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DTSTART;TZID=America/New_York:20190318T090000
DTEND;TZID=America/New_York:20190320T170000
DTSTAMP:20250304T213630Z
CREATED:20230715T091111Z
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SUMMARY:Workshop on Mirror Symmetry and Stability
DESCRIPTION:This three-day workshop will take place at Harvard University on March 18-20\, 2019 in Science Center room 507. The main topic will be stability conditions in homological mirror symmetry. This workshop is funded by the Simons Collaboration in Homological Mirror Symmetry. \nOrganizers: Denis Auroux\, Yu-Wei Fan\, Hansol Hong\, Siu-Cheong Lau\, Bong Lian\, Shing-Tung Yau\, Jingyu Zhao \nSpeakers: \nDylan Allegretti (Sheffield)\nTristan Collins (MIT)\nNaoki Koseki (Tokyo)\nChunyi Li (Warwick)\nJason Lo (CSU Northridge)\nEmanuele Macrì (NEU & IHES)\nGenki Ouchi (Riken iTHEMS)\nPranav Pandit (ICTS)\nLaura Pertusi (Edinburgh)\nJacopo Stoppa (SISSA)\nAlex Takeda (UC Berkeley)\nXiaolei Zhao (UC Santa Barbara) \nMore details will be added later. \nVisit the event page for more information.  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/workshop-on-mirror-symmetry-and-stability/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
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DTSTART;TZID=America/New_York:20190327T090000
DTEND;TZID=America/New_York:20190329T160000
DTSTAMP:20250304T213810Z
CREATED:20230715T172858Z
LAST-MODIFIED:20250304T213810Z
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SUMMARY:Machine Learning for Multiscale Model Reduction Workshop
DESCRIPTION:The Machine Learning for Multiscale Model Reduction Workshop will take place on March 27-29\, 2019. This is the second of two workshops organized by Michael Brenner\, Shmuel Rubinstein\, and Tom Hou.  The first\, Fluid turbulence and Singularities of the Euler/ Navier Stokes equations\, will take place on March 13-15\, 2019. Both workshops will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.  \n  \nSpeakers:\n\nJoan Bruna\, Courant Institute\nPredrag Cvitanovic\, Georgia Tech\nStephan Hoyer\, Google Research\nDe Huang\, Caltech\nGeorge Karniadakis\, Brown University\nRichard Kerswell\, Cambridge University\nStephane Mallat\, ENS\nStanley Osher\, UCLA\nJacob Page\, Cambridge University\nHouman Owhadi\, Caltech\nZuowei Shen\, National University of Singapore\nJack Xin\, UC Irvine\nJinchao Xu\, Penn State University\nLexing Ying\, Stanford University and Facebook AI Research\nPengchuan Zhang\, Microsoft Research
URL:https://cmsa.fas.harvard.edu/event/machine-learning-for-multiscale-model-reduction-workshop/
LOCATION:Virtual
CATEGORIES:Event,Workshop
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DTSTART;TZID=America/New_York:20190409T160000
DTEND;TZID=America/New_York:20190409T170000
DTSTAMP:20250328T150617Z
CREATED:20240212T100146Z
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SUMMARY:Math Science Lectures in Honor of Raoul Bott: Mina Aganagic
DESCRIPTION:On April 9 and 10\, 2019 the CMSA hosted two lectures by Mina Aganagic (UC Berkeley).  This was the second annual Math Science Lecture Series held in honor of Raoul Bott. \nThe lectures took place in Science Center\, Hall C \n“Two math lessons from string theory”\n\n\n\n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n \n \nApril 9\, 2019 \nLecture 1 \nTitle: “Lesson on Integrability” \nAbstract: The quantum Knizhnik-Zamolodchikov (qKZ) equation is a difference generalization of the famous Knizhnik-Zamolodchikov (KZ) equation. The problem to explicitly capture the monodromy of the qKZ equation has been open for over 25 years. I will describe the solution to this problem\, discovered jointly with Andrei Okounkov. The solution comes from the geometry of Nakajima quiver varieties and has a string theory origin. \nPart of the interest in the qKZ monodromy problem is that its solution leads to integrable lattice models\, in parallel to how monodromy matrices of the KZ equation lead to knot invariants. Thus\, our solution of the problem leads to a new\, geometric approach\, to integrable lattice models. There are two other approaches to integrable lattice models\, due to Nekrasov and Shatashvili and to Costello\, Witten and Yamazaki. I’ll describe joint work with Nikita Nekrasov which explains how string theory unifies the three approaches to integrable lattice models.\n\n\n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n \n \nApril 10\, 2019 \nLecture 2 \nTitle: “Lesson on Knot Categorification” \nAbstract: An old problem is to find a unified approach to the knot categorification problem. The new string theory perspective on the qKZ equation I described in the first talk can be used to derive two geometric approaches to the problem. \nThe first approach is based on a category of B-type branes on resolutions of slices in affine Grassmannians. The second is based on a category of A-branes in a Landau-Ginzburg theory. The relation between them is two dimensional (equivariant) mirror symmetry. String theory also predicts that a third approach to categorification\, based on counting solutions to five dimensional Haydys-Witten equations\, is equivalent to the first two. \nThis talk is mostly based on joint work with Andrei Okounkov.\n\n\n\n  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/math-science-lectures-in-honor-of-raoul-bott-mina-aganagic/
LOCATION:Harvard Science Center\, 1 Oxford Street\, Cambridge\, MA\, 02138
CATEGORIES:Event,Math Science Lectures in Honor of Raoul Bott,Public Lecture,Special Lectures
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DTSTART;TZID=America/New_York:20190415T091500
DTEND;TZID=America/New_York:20190417T160000
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SUMMARY:Workshop on Invariance and Geometry in Sensation\, Action and Cognition
DESCRIPTION:As part of the program on Mathematical Biology a workshop on Invariance and Geometry in Sensation\, Action and Cognition will take place on April 15-17\, 2019. \nLegend has it that above the door to Plato’s Academy was inscribed “Μηδείς άγεωµέτρητος είσίτω µον τήν στέγην”\, translated as “Let no one ignorant of geometry enter my doors”. While geometry and invariance has always been a cornerstone of mathematics\, it has traditionally not been an important part of biology\, except in the context of aspects of structural biology. The premise of this meeting is a tantalizing sense that geometry and invariance are also likely to be important in (neuro)biology and cognition. Since all organisms interact with the physical world\, this implies that as neural systems extract information using the senses to guide action in the world\, they need appropriately invariant representations that are stable\, reproducible and capable of being learned. These invariances are a function of the nature and type of signal\, its corruption via noise\, and the method of storage and use. \nThis hypothesis suggests many puzzles and questions: What representational geometries are reflected in the brain? Are they learned or innate? What happens to the invariances under realistic assumptions about noise\, nonlinearity and finite computational resources? Can cases of mental disorders and consequences of brain damage be characterized as break downs in representational invariances? Can we harness these invariances and sensory contingencies to build more intelligent machines? The aim is to revisit these old neuro-cognitive problems using a series of modern lenses experimentally\, theoretically and computationally\, with some tutorials on how the mathematics and engineering of invariant representations in machines and algorithms might serve as useful null models. \nIn addition to talks\, there will be a set of tutorial talks on the mathematical description of invariance (P.J. Olver)\, the computer vision aspects of invariant algorithms (S. Soatto)\, and the neuroscientific and cognitive aspects of invariance (TBA). The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. This workshop is organized by L. Mahadevan (Harvard)\, Talia Konkle (Harvard)\, Samuel Gershman (Harvard)\, and Vivek Jayaraman (HHMI). \nVideos\nTentative Speaker List: \n\nAlessandro Achille\, UCLA\nVijay Balasubramanian\, University of Pennsylvania\nJeannette Bohg\, Stanford\nEd Connor\, Johns Hopkins\nMoira Dillon\, NYU\nJacob Feldman\, Rutgers\nIla Fiete\, MIT\nSam Gershman\, Harvard\nGily Ginosar\, Weizmann Institute of Science\nLucia Jacobs\, UC Berkeley\nVivek Jayaraman\, HHMI\nTalia Konkle\, Harvard\nL. Mahadevan\, Harvard\nMichael McCloskey\, Johns Hopkins\nSam Ocko\, Stanford\nPeter Olver\, University of Minnesota\nAnitha Pasupathy\, University of Washington\nSandro Romani\, Janelia\nStefano Soatto\, UCLA\nTatyana Sharpee\,  Salk Institute\nDagmar Sternad\, Northeastern\nElizabeth Torres\, Rutgers\n\nSchedule:\nMonday\, April 15 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 9:15am\nWelcome and Introduction\n\n\n\n9:15 – 10:00am\nVivek Jayaraman\nTitle: Insect cognition: Small tales of geometry & invariance \nAbstract: Decades of field and laboratory experiments have allowed ethologists to discover the remarkable sophistication of insect behavior. Over the past couple of decades\, physiologists have been able to peek under the hood to uncover sophistication in insect brain dynamics as well. In my talk\, I will describe phenomena that relate to the workshop’s theme of geometry and invariance. I will outline how studying insects —and flies in particular— may enable an understanding of the neural mechanisms underlying these intriguing phenomena.\n\n\n10:00 – 10:45am\nElizabeth Torres\nTitle: Connecting Cognition and Biophysical Motions Through Geometric Invariants and Motion Variability \nAbstract: In the 1930s Nikolai Bernstein defined the degrees of freedom (DoF) problem. He asked how the brain could control abundant DoF and produce consistent solutions\, when the internal space of bodily configurations had much higher dimensions than the space defining the purpose(s) of our actions. His question opened two fundamental problems in the field of motor control. One relates to the uniqueness or consistency of a solution to the DoF problem\, while the other refers to the characterization of the diverse patterns of variability that such solution produces. \nIn this talk I present a general geometric solution to Bernstein’s DoF problem and provide empirical evidence for symmetries and invariances that this solution provides during the coordination of complex naturalistic actions. I further introduce fundamentally different patterns of variability that emerge in deliberate vs. spontaneous movements discovered in my lab while studying athletes and dancers performing interactive actions. I here reformulate the DoF problem from the standpoint of the social brain and recast it considering graph theory and network connectivity analyses amenable to study one of the most poignant developmental disorders of our times: Autism Spectrum Disorders. \nI offer a new unifying framework to recast dynamic and complex cognitive and social behaviors of the full organism and to characterize biophysical motion patterns during migration of induced pluripotent stem cell colonies on their way to become neurons.\n\n\n10:45 – 11:15am\nCoffee Break\n\n\n\n11:15 – 12:00pm\nPeter Olver\nTitle: Symmetry and invariance in cognition — a mathematical perspective” \nAbstract: Symmetry recognition and appreciation is fundamental in human cognition.  (It is worth speculating as to why this may be so\, but that is not my intent.) The goal of these two talks is to survey old and new mathematical perspectives on symmetry and invariance.  Applications will arise from art\, computer vision\, geometry\, and beyond\, and will include recent work on 2D and 3D jigsaw puzzle assembly and an ongoing collaboration with anthropologists on the analysis and refitting of broken bones.  Mathematical prerequisites will be kept to a bare minimum.\n\n\n12:00 – 12:45pm\nStefano Soatto/Alessandro Achille\nTitle: Information in the Weights and Emergent Properties of Deep Neural Networks \nAbstract: We introduce the notion of information contained in the weights of a Deep Neural Network  and show that it can be used to control and describe the training process of DNNs\, and can explain how properties\, such as invariance to nuisance variability and disentanglement\, emerge naturally in the learned representation. Through its dynamics\, stochastic gradient descent (SGD) implicitly regularizes the information in the weights\, which can then be used to bound the generalization error through the PAC-Bayes bound. Moreover\, the information in the weights can be used to defined both a topology and an asymmetric distance in the space of tasks\, which can then be used to predict the training time and the performance on a new task given a solution to a pre-training task. \nWhile this information distance models difficulty of transfer in first approximation\, we show the existence of non-trivial irreversible dynamics during the initial transient phase of convergence when the network is acquiring information\, which makes the approximation fail. This is closely related to critical learning periods in biology\, and suggests that studying the initial convergence transient can yield important insight beyond those that can be gleaned from the well-studied asymptotics.\n\n\n12:45 – 2:00pm\nLunch\n\n\n\n2:00 – 2:45pm\nAnitha Pasupathy\nTitle: Invariant and non-invariant representations in mid-level ventral visual cortex \nMy laboratory investigates how visual form is encoded in area V4\, a critical mid-level stage of form processing in the macaque monkey. Our goal is to reveal how V4 representations underlie our ability to segment visual scenes and recognize objects. In my talk I will present results from two experiments that highlight the different strategies used by the visual to achieve these goals. First\, most V4 neurons exhibit form tuning that is exquisitely invariant to size and position\, properties likely important to support invariant object recognition. On the other hand\, form tuning in a majority of neurons is also highly dependent on the interior fill. Interestingly\, unlike primate V4 neurons\, units in a convolutional neural network trained to recognize objects (AlexNet) overwhelmingly exhibit fill-outline invariance. I will argue that this divergence between real and artificial circuits reflects the importance of local contrast in parsing visual scenes and overall scene understanding.\n\n\n2:45 – 3:30pm\nJacob Feldman\nTitle: Bayesian skeleton estimation for shape representation and perceptual organization \nAbstract: In this talk I will briefly summarize a framework in which shape representation and perceptual organization are reframed as probabilistic estimation problems. The approach centers around the goal of identifying the skeletal model that best “explains” a given shape. A Bayesian solution to this problem requires identifying a prior over shape skeletons\, which penalizes complexity\, and a likelihood model\, which quantifies how well any particular skeleton model fits the data observed in the image. The maximum-posterior skeletal model thus constitutes the most “rational” interpretation of the image data consistent with the given assumptions. This approach can easily be extended and generalized in a number of ways\, allowing a number of traditional problems in perceptual organization to be “probabilized.” I will briefly illustrate several such extensions\, including (1) figure/ground and grouping (3) 3D shape and (2) shape similarity.\n\n\n3:30 – 4:00pm\nTea Break\n\n\n\n4:00 – 4:45pm\nMoira Dillon\nTitle: Euclid’s Random Walk: Simulation as a tool for geometric reasoning through development \nAbstract: Formal geometry lies at the foundation of millennia of human achievement in domains such as mathematics\, science\, and art. While formal geometry’s propositions rely on abstract entities like dimensionless points and infinitely long lines\, the points and lines of our everyday world all have dimension and are finite. How\, then\, do we get to abstract geometric thought? In this talk\, I will provide evidence that evolutionarily ancient and developmentally precocious sensitivities to the geometry of our everyday world form the foundation of\, but also limit\, our mathematical reasoning. I will also suggest that successful geometric reasoning may emerge through development when children abandon incorrect\, axiomatic-based strategies and come to rely on dynamic simulations of physical entities. While problems in geometry may seem answerable by immediate inference or by deductive proof\, human geometric reasoning may instead rely on noisy\, dynamic simulations.\n\n\n4:45 – 5:30pm\nMichael McCloskey\nTitle: Axes and Coordinate Systems in Representing Object Shape and Orientation \nAbstract: I describe a theoretical perspective in which a) object shape is represented in an object-centered reference frame constructed around orthogonal axes; and b) object orientation is represented by mapping the object-centered frame onto an extrinsic (egocentric or environment-centered) frame.  I first show that this perspective is motivated by\, and sheds light on\, object orientation errors observed in neurotypical children and adults\, and in a remarkable case of impaired orientation perception. I then suggest that orientation errors can be used to address questions concerning how object axes are defined on the basis of object geometry—for example\, what aspects of object geometry (e.g.\, elongation\, symmetry\, structural centrality of parts) play a role in defining an object principal axis?\n\n\n5:30 – 6:30pm\nReception\n\n\n\n\n \nTuesday\, April 16 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 9:45am\nPeter Olver\nTitle: Symmetry and invariance in cognition — a mathematical perspective” \nAbstract: Symmetry recognition and appreciation is fundamental in human cognition.  (It is worth speculating as to why this may be so\, but that is not my intent.) The goal of these two talks is to survey old and new mathematical perspectives on symmetry and invariance.  Applications will arise from art\, computer vision\, geometry\, and beyond\, and will include recent work on 2D and 3D jigsaw puzzle assembly and an ongoing collaboration with anthropologists on the analysis and refitting of broken bones.  Mathematical pre\n\n\n9:45 – 10:30am\nStefano Soatto/Alessandro Achille\nTitle: Information in the Weights and Emergent Properties of Deep Neural Networks \nAbstract: We introduce the notion of information contained in the weights of a Deep Neural Network  and show that it can be used to control and describe the training process of DNNs\, and can explain how properties\, such as invariance to nuisance variability and disentanglement\, emerge naturally in the learned representation. Through its dynamics\, stochastic gradient descent (SGD) implicitly regularizes the information in the weights\, which can then be used to bound the generalization error through the PAC-Bayes bound. Moreover\, the information in the weights can be used to defined both a topology and an asymmetric distance in the space of tasks\, which can then be used to predict the training time and the performance on a new task given a solution to a pre-training task. \nWhile this information distance models difficulty of transfer in first approximation\, we show the existence of non-trivial irreversible dynamics during the initial transient phase of convergence when the network is acquiring information\, which makes the approximation fail. This is closely related to critical learning periods in biology\, and suggests that studying the initial convergence transient can yield important insight beyond those that can be gleaned from the well-studied asymptotics.\n\n\n10:30 – 11:00am\nCoffee Break\n\n\n\n11:00 – 11:45am\nJeannette Bohg\nTitle: On perceptual representations and how they interact with actions and physical representations \nAbstract: I will discuss the hypothesis that perception is active and shaped by our task and our expectations on how the world behaves upon physical interaction. Recent approaches in robotics follow this insight that perception is facilitated by physical interaction with the environment. First\, interaction creates a rich sensory signal that would otherwise not be present. And second\, knowledge of the regularity in the combined space of sensory data and action parameters facilitate the prediction and interpretation of the signal. In this talk\, I will present two examples from our previous work where a predictive task facilitates autonomous robot manipulation by biasing the representation of the raw sensory data. I will present results on visual but also haptic data.\n\n\n11:45 – 12:30pm\nDagmar Sternad\nTitle: Exploiting the Geometry of the Solution Space to Reduce Sensitivity to Neuromotor Noise \nAbstract: Control and coordination of skilled action is frequently examined in isolation as a neuromuscular problem. However\, goal-directed actions are guided by information that creates solutions that are defined as a relation between the actor and the environment. We have developed a task-dynamic approach that starts with a physical model of the task and mathematical analysis of the solution spaces for the task. Based on this analysis we can trace how humans develop strategies that meet complex demands by exploiting the geometry of the solution space. Using three interactive tasks – throwing or bouncing a ball and transporting a “cup of coffee” – we show that humans develop skill by: 1) finding noise-tolerant strategies and channeling noise into task-irrelevant dimensions\, 2) exploiting solutions with dynamic stability\, and 3) optimizing predictability of the object dynamics. These findings are the basis for developing propositions about the controller: complex actions are generated with dynamic primitives\, attractors with few invariant types that overcome substantial delays and noise in the neuro-mechanical system.\n\n\n12:30 – 2:00pm\nLunch\n\n\n\n2:00 – 2:45pm\nSam Ocko\nTitle: Emergent Elasticity in the Neural Code for Space \nAbstract: To navigate a novel environment\, animals must construct an internal map of space by combining information from two distinct sources: self-motion cues and sensory perception of landmarks. How do known aspects of neural circuit dynamics and synaptic plasticity conspire to construct such internal maps\, and how are these maps used to maintain representations of an animal’s position within an environment. We demonstrate analytically how a neural attractor model that combines path integration of self-motion with Hebbian plasticity in synaptic weights from landmark cells can self-organize a consistent internal map of space as the animal explores an environment. Intriguingly\, the emergence of this map can be understood as an elastic relaxation process between landmark cells mediated by the attractor network during exploration. Moreover\, we verify several experimentally testable predictions of our model\, including: (1) systematic deformations of grid cells in irregular environments\, (2) path-dependent shifts in grid cells towards the most recently encountered landmark\, (3) a dynamical phase transition in which grid cells can break free of landmarks in altered virtual reality environments and (4) the creation of topological defects in grid cells. Taken together\, our results conceptually link known biophysical aspects of neurons and synapses to an emergent solution of a fundamental computational problem in navigation\, while providing a unified account of disparate experimental observations.\n\n\n2:45 – 3:30pm\nTatyana Sharpee\nTitle: Hyperbolic geometry of the olfactory space \nAbstract: The sense of smell can be used to avoid poisons or estimate a food’s nutrition content because biochemical reactions create many by-products. Thus\, the production of a specific poison by a plant or bacteria will be accompanied by the emission of certain sets of volatile compounds. An animal can therefore judge the presence of poisons in the food by how the food smells. This perspective suggests that the nervous system can classify odors based on statistics of their co-occurrence within natural mixtures rather than from the chemical structures of the ligands themselves. We show that this statistical perspective makes it possible to map odors to points in a hyperbolic space. Hyperbolic coordinates have a long but often underappreciated history of relevance to biology. For example\, these coordinates approximate distance between species computed along dendrograms\, and more generally between points within hierarchical tree-like networks. We find that both natural odors and human perceptual descriptions of smells can be described using a three-dimensional hyperbolic space. This match in geometries can avoid distortions that would otherwise arise when mapping odors to perception. We identify three axes in the perceptual space that are aligned with odor pleasantness\, its molecular boiling point and acidity. Because the perceptual space is curved\, one can predict odor pleasantness by knowing the coordinates along the molecular boiling point and acidity axes.\n\n\n3:30 – 4:00pm\nTea Break\n\n\n\n4:00 – 4:45pm\nEd Connor\nTitle: Representation of solid geometry in object vision cortex \nAbstract: There is a fundamental tension in object vision between the 2D nature of retinal images and the 3D nature of physical reality. Studies of object processing in the ventral pathway of primate visual cortex have focused mainly on 2D image information. Our latest results\, however\, show that representations of 3D geometry predominate even in V4\, the first object-specific stage in the ventral pathway. The majority of V4 neurons exhibit strong responses and clear selectivity for solid\, 3D shape fragments. These responses are remarkably invariant across radically different image cues for 3D shape: shading\, specularity\, reflection\, refraction\, and binocular disparity (stereopsis). In V4 and in subsequent stages of the ventral pathway\, solid shape geometry is represented in terms of surface fragments and medial axis fragments. Whole objects are represented by ensembles of neurons signaling the shapes and relative positions of their constituent parts. The neural tuning dimensionality of these representations includes principal surface curvatures and their orientations\, surface normal orientation\, medial axis orientation\, axial curvature\, axial topology\, and position relative to object center of mass. Thus\, the ventral pathway implements a rapid transformation of 2D image data into explicit representations 3D geometry\, providing cognitive access to the detailed structure of physical reality.\n\n\n4:45 – 5:30pm\nL. Mahadevan\nTitle: Simple aspects of geometry and probability in perception \nAbstract: Inspired by problems associated with noisy perception\, I will discuss two questions: (i) how might we test people’s perception of probability in a geometric context ? (ii) can one construct invariant descriptions of 2D images using simple notions of probabilistic geometry? Along the way\, I will highlight other questions that the intertwining of geometry and probability raises in a broader perceptual context.\n\n\n\n\nWednesday\, April 17 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 9:45am\nGily Ginosar\nTitle: The 3D geometry of grid cells in flying bats \nAbstract: The medial entorhinal cortex (MEC) contains a variety of spatial cells\, including grid cells and border cells. In 2D\, grid cells fire when the animal passes near the vertices of a 2D spatial lattice (or grid)\, which is characterized by circular firing-fields separated by fixed distances\, and 60 local angles – resulting in a hexagonal structure. Although many animals navigate in 3D space\, no studies have examined the 3D volumetric firing of MEC neurons. Here we addressed this by training Egyptian fruit bats to fly in a large room (5.84.62.7m)\, while we wirelessly recorded single neurons in MEC. We found 3D border cells and 3D head-direction cells\, as well as many neurons with multiple spherical firing-fields. 20% of the multi-field neurons were 3D grid cells\, exhibiting a narrow distribution of characteristic distances between neighboring fields – but not a perfect 3D global lattice. The 3D grid cells formed a functional continuum with less structured multi-field neurons. Both 3D grid cells and multi-field cells exhibited an anatomical gradient of spatial scale along the dorso-ventral axis of MEC\, with inter-field spacing increasing ventrally – similar to 2D grid cells in rodents. We modeled 3D grid cells and multi-field cells as emerging from pairwise-interactions between fields\, using an energy potential that induces repulsion at short distances and attraction at long distances. Our analysis shows that the model explains the data significantly better than a random arrangement of fields. Interestingly\, simulating the exact same model in 2D yielded a hexagonal-like structure\, akin to grid cells in rodents. Together\, the experimental data and preliminary modeling suggest that the global property of grid cells is multiple fields that repel each other with a characteristic distance-scale between adjacent fields – which in 2D yields a global hexagonal lattice while in 3D yields only local structure but no global lattice. \nGily Ginosar 1 \, Johnatan Aljadeff 2 \, Yoram Burak 3 \, Haim Sompolinsky 3 \, Liora Las 1 \, Nachum Ulanovsky 1 \n(1) Department of Neurobiology\, Weizmann Institute of Science\, Rehovot 76100\, Israel \n(2) Department of Bioengineering\, Imperial College London\, London\, SW7 2AZ\, UK \n(3) The Edmond and Lily Safra Center for Brain Sciences\, and Racah Institute of Physics\, The Hebrew \nUniversity of Jerusalem\, Jerusalem\, 91904\, Israel\n\n\n9:45 – 10:30am\nSandro Romani\nTitle: Neural networks for 3D rotations \nAbstract: Studies in rodents\, bats\, and humans have uncovered the existence of neurons that encode the orientation of the head in 3D. Classical theories of the head-direction (HD) system in 2D rely on continuous attractor neural networks\, where neurons with similar heading preference excite each other\, while inhibiting other HD neurons. Local excitation and long-range inhibition promote the formation of a stable “bump” of activity that maintains a representation of heading. The extension of HD models to 3D is hindered by complications (i) 3D rotations are non-commutative (ii) the space described by all possible rotations of an object has a non-trivial topology. This topology is not captured by standard parametrizations such as Euler angles (e.g. yaw\, pitch\, roll). For instance\, with these parametrizations\, a small change of the orientation of the head could result in a dramatic change of neural representation. We used methods from the representation theory of groups to develop neural network models that exhibit patterns of persistent activity of neurons mapped continuously to the group of 3D rotations. I will further discuss how these networks can (i) integrate vestibular inputs to update the representation of heading\, and (ii) be used to interpret “mental rotation” experiments in humans. \nThis is joint work with Hervé Rouault (CENTURI) and Alon Rubin (Weizmann Institute of Science).\n\n\n10:30 – 11:00am\nCoffee Break\n\n\n\n11:00 – 11:45am\nSam Gershman\nTitle: The hippocampus as a predictive map \nAbstract: A cognitive map has long been the dominant metaphor for hippocampal function\, embracing the idea that place cells encode a geometric representation of space. However\, evidence for predictive coding\, reward sensitivity and policy dependence in place cells suggests that the representation is not purely spatial. I approach this puzzle from a reinforcement learning perspective: what kind of spatial representation is most useful for maximizing future reward? I show that the answer takes the form of a predictive representation. This representation captures many aspects of place cell responses that fall outside the traditional view of a cognitive map. Furthermore\, I argue that entorhinal grid cells encode a low-dimensionality basis set for the predictive representation\, useful for suppressing noise in predictions and extracting multiscale structure for hierarchical planning.\n\n\n11:45 – 12:30pm\nLucia Jacobs\nTitle: The adaptive geometry of a chemosensor: the origin and function of the vertebrate nose \nAbstract: A defining feature of a living organism\, from prokaryotes to plants and animals\, is the ability to orient to chemicals. The distribution of chemicals\, whether in water\, air or on land\, is used by organisms to locate and exploit spatially distributed resources\, such as nutrients and reproductive partners. In animals\, the evolution of a nervous system coincided with the evolution of paired chemosensors. In contemporary insects\, crustaceans\, mollusks and vertebrates\, including humans\, paired chemosensors confer a stereo olfaction advantage on the animal’s ability to orient in space. Among vertebrates\, however\, this function faced a new challenge with the invasion of land. Locomotion on land created a new conflict between respiration and spatial olfaction in vertebrates. The need to resolve this conflict could explain the current diversity of vertebrate nose geometries\, which could have arisen due to species differences in the demand for stereo olfaction. I will examine this idea in more detail in the order Primates\, focusing on Old World primates\, in particular\, the evolution of an external nose in the genus Homo.\n\n\n12:30 – 1:30pm\nLunch\n\n\n\n1:30 – 2:15pm\nTalia Konkle\nTitle: The shape of things and the organization of object-selective cortex \nAbstract: When we look at the world\, we effortlessly recognize the objects around us and can bring to mind a wealth of knowledge about their properties. In part 1\, I’ll present evidence that neural responses to objects are organized by high-level dimensions of animacy and size\, but with underlying neural tuning to mid-level shape features. In part 2\, I’ll present evidence that representational structure across much of the visual system has the requisite structure to predict visual behavior. Together\, these projects suggest that there is a ubiquitous “shape space” mapped across all of occipitotemporal cortex that underlies our visual object processing capacities. Based on these findings\, I’ll speculate that the large-scale spatial topography of these neural responses is critical for pulling explicit content out of a representational geometry.\n\n\n2:15 – 3:00pm\nVijay Balasubramanian\nTitle: Becoming what you smell: adaptive sensing in the olfactory system \nAbstract: I will argue that the circuit architecture of the early olfactory system provides an adaptive\, efficient mechanism for compressing the vast space of odor mixtures into the responses of a small number of sensors.  In this view\, the olfactory sensory repertoire employs a disordered code to compress a high dimensional olfactory space into a low dimensional receptor response space while preserving distance relations between odors.  The resulting representation is dynamically adapted to efficiently encode the changing environment of volatile molecules.  I will show that this adaptive combinatorial code can be efficiently decoded by systematically eliminating candidate odorants that bind to silent receptors.  The resulting algorithm for “estimation by elimination” can be implemented by a neural network that is remarkably similar to the early olfactory pathway in the brain.  The theory predicts a relation between the diversity of olfactory receptors and the sparsity of their responses that matches animals from flies to humans.   It also predicts specific deficits in olfactory behavior that should result from optogenetic manipulation of the olfactory bulb.\n\n\n3:00 – 3:45pm\nIla Feite\nTitle: Invariance\, stability\, geometry\, and flexibility in spatial navigation circuits \nAbstract: I will describe how the geometric invariances or symmetries of the external world are reflected in the symmetries of neural circuits that represent it\, using the example of the brain’s networks for spatial navigation. I will discuss how these symmetries enable spatial memory\, evidence integration\, and robust representation. At the same time\, I will discuss how these seemingly rigid circuits with their inscribed symmetries can be harnessed to represent a range of spatial and non-spatial cognitive variables with high flexibility.\n\n\n3:45 – 4:00pm\nL Mahadevan – summary
URL:https://cmsa.fas.harvard.edu/event/workshop-on-invariance-and-geometry-in-sensation-action-and-cognition/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190418T160000
DTEND;TZID=America/New_York:20190418T170000
DTSTAMP:20250328T150900Z
CREATED:20230715T174140Z
LAST-MODIFIED:20250328T150900Z
UID:10000113-1555603200-1555606800@cmsa.fas.harvard.edu
SUMMARY:Yip Annual Lecture
DESCRIPTION:On April 18\, 2019 Harvard CMSA hosted the inaugural Yip lecture. The Yip Lecture takes place thanks to the support of Dr. Shing-Yiu Yip. This year’s speaker was Peter Galison (Harvard Physics). \nThe lecture was held from 4:00-5:00pm in Science Center\, Hall A.
URL:https://cmsa.fas.harvard.edu/event/yip-annual-lecture/
LOCATION:Harvard Science Center\, 1 Oxford Street\, Cambridge\, MA\, 02138
CATEGORIES:Event,Public Lecture,Special Lectures,Yip Lecture Series
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Yip-3-1-791x1024-1-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190429T090000
DTEND;TZID=America/New_York:20190501T170000
DTSTAMP:20250304T214254Z
CREATED:20230715T174721Z
LAST-MODIFIED:20250304T214254Z
UID:10000114-1556528400-1556730000@cmsa.fas.harvard.edu
SUMMARY:Conference on Algebraic Geometry\, Representation theory and Mathematical Physics
DESCRIPTION:From April 29 to May 1\, 2019 the CMSA will be hosting a Conference on Algebraic Geometry\, Representation theory and Mathematical Physics. This workshop is organized by Bong Lian (Brandeis) and Artan Sheshmani (CMSA) . The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.   \nVideos\nSpeakers: \n\nDan Abramovich\, Brown\nRoman Bezrukavnikov\, MIT\nFedor Bogomolov\, NYU\nQile Chen\, Boston College\nDawei Chen\, Boston College\nAlexander Efimov\, Moscow\nPavel Etingof\, MIT\nMaksym Fedorchuk\, Boston College\nDennis Gaitsgory\, Harvard\nAmin Gholampour\, Maryland\nBrendan Hassett\, Brown\nLudmil Katzarkov\, Miami & Moscow\nSi Li\, Tsinghua\nAndrei Negut\, MIT\nYuri Tschinkel\, NYU\nWei Zhang\, MIT\n\n  \nMonday\, April 29 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 10:00am\nWei Zhang\, MIT\nTitle: The arithmetic fundamental lemma for diagonal cycles \nAbstract: I’ll recall the Gross–Zagier theorem and a high dimensional generalization\, the arithmetic Gan-Gross-Prasad conjecture\, which relates the height pairing of arithmetic diagonal cycles on certain shimura varieties to the first order derivative of certain L-functions.  The arithmetic fundamental lemma conjecture arises from the relative trace formula approach to this conjecture. I will recall the statement of the arithmetic fundamental lemma and outline a proof.\n\n\n10:00 – 10:30am\nBreak\n\n\n\n10:30 – 11:30am\nYuri Tschinkel\, NYU\nTitle: Equivariant birational geometry and modular symbols \nAbstract: We introduce new invariants in equivariant birational geometry and study their relation to modular symbols and cohomology of arithmetic groups (joint with M. Kontsevich and V. Pestun).\n\n\n11:30 – 1:30pm\nLunch\n\n\n\n1:30 – 2:30pm\nAlexander Efimov\, Moscow\nTitle: Torsionness for regulators of canonical extensions \nAbstract: I will sketch a generalization of the results of Iyer and Simpson arXiv:0707.0372 to the general case of a normal-crossings divisor at infinity.\n\n\n2:30 – 3:00pm\nBreak\n\n\n\n3:00 – 4:00pm\nAmin Gholampour\, Maryland\nTitle: Euler Characteristics of punctual quot schemes on threefolds \nAbstract: Let F be a homological dimension 1 torsion free sheaf on a nonsingular quasi-projective threefold. The first cohomology of the derived dual of F is a 1-dimension sheaf G supported on the singular locus of F. We prove a wall-crossing formula relating the generating series of the Euler characteristics of Quot(F\, n) and Quot(G\,n)\, where Quot(-\,n) denotes the quot scheme of length n quotients. We will use this relation in studying the Euler characteristics of the moduli spaces of stable torsion free sheaves on nonsingular projective threefolds. This is a joint work with Martijn Kool.\n\n\n4:00 – 4:30pm\nBreak\n\n\n\n4:30 – 5:30pm\nMaksym Fedorchuck\, BC\nTitle:  Stability of one-parameter families of weighted hypersurfaces \nAbstract:  We define a notion of stability for fibrations over a curve with generic fibers being weighted hypersurfaces (in some weighted projective space) generalizing Kollár’s stability for families of hypersurfaces in a projective space.  The stability depends on a choice of an effective line bundle on the parameter space of weighted hypersurfaces and different choices pick out different birational model of the total space of the fibration. I will describe enumerative geometry that goes into understanding these stability conditions\, and\, if time permits\, examples where this machinery can be used to produce birational models with good properties.  Joint work with Hamid Ahmadinezhad and Igor Krylov.\n\n\n\n  \nTuesday\, April 30 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 10:00am\nBrendan Hassett\, Brown\nTitle: Rationality for geometrically rational threefolds \nAbstract: We consider rationality questions for varieties over non-closed fields that become rational over an algebraic closure\, like smooth complete intersections of two quadrics.  (joint with Tschinkel)\n\n\n10:00 – 10:30am\nBreak\n\n\n\n10:30 – 11:30am\nDennis Gaitsgory\, Harvard\nTitle: The Fundamental Local Equivalence in quantum geometric Langlands \nAbstract: The Fundamental Local Equivalence is statement that relates the q-twisted  Whittaker category of the affine Grassmannian for the group G and the category of modules over the Langlands dual “big” quantum group. The non-triviaiity of the statement lies is the fact that the relationship between the group and its  dual is combinatorial\, so to prove the FLE one needs to express both sides in combinatorial terms. In the talk we will indicate the proof of a related statement for the “small” quantum group. The combinatorial link is provided by the category of factorization modules over a certain factorization algebra\, which in itself is a geometric device that concisely encodes the root data.\n\n\n11:30 – 1:00pm\nLunch\n\n\n\n1:00- 2:00pm\nAndrei Negut\, MIT\nTitle: AGT relations in geometric representation theory \nAbstract: I will survey a program that seeks to translate the Alday-Gaiotto-Tachikawa correspondence (between gauge theory on R^4 and conformal field theory) into the language of algebraic geometry. The objects of study become moduli spaces of sheaves on surfaces\, and the goal is to connect them with the W-algebra of type gl_n.\n\n\n2:00 – 2:15pm\nBreak\n\n\n\n2:15 – 3:15pm\nDan Abramovich\, Brown\nTitle: Resolution in characteristic 0 using weighted blowing up \nAbstract: Given a variety $X$\, one wants to blow up the worst singular locus\, show that it gets better\, and iterate until the singularities are resolved. \nExamples such as the whitney umbrella show that this iterative process cannot be done by blowing up smooth loci – it goes into a loop. \nWe show that there is a functorial way to resolve varieties using \emph{weighted} blowings up\, in the stack-theoretic sense. To an embedded variety $X \subset Y$ one functorially assigns an invariant $(a_1\,\ldots\,a_k)$\, and a center locally of the form $(x_1^{a_1} \, \ldots \, x_k^{a_k})$\, whose stack-theoretic weighted blowing up has strictly smaller invariant under the lexicographic order. \nThis is joint work with Michael Tëmkin (Jerusalem) and Jaroslaw Wlodarczyk (Purdue)\, a side product of our work on functorial semistable reduction. A similar result was discovered by G. Marzo and M. McQuillan.\n\n\n3:15 – 3:30pm\nBreak\n\n\n\n3:30 – 4:30pm\nFedor Bogomolov\, NYU\nTitle: On the base of a Lagrangian fibration for a compact hyperkahler manifold. \nAbstract: In my talk I will discuss our proof with N. Kurnosov that the base of such fibration for complex projective manifold hyperkahler manifold of dimension $4$ is always a projective plane $P^2$. In fact we show that the base of such fibration can not have a singular point of type $E_8$. It was by the theorem of Matsushita and others that only quotient singularities can occur and if the base is smooth then the it is isomorphic to $P^2$. The absence of other singularities apart from $E_8$ has been already known and we show that $E-8$ can not occur either. Our method can be applied to other types of singularities for the study of  Lagrangian fibrations in higher dimensions More recently similar result was obtained by Huybrechts and Xu.\n\n\n4:30 – 4:45pm\nBreak\n\n\n\n4:45 – 5:45pm\nDawei Chen\, BC\nTitle: Volumes and intersection theory on moduli spaces of Abelian differentials \nAbstract: Computing volumes of moduli spaces has significance in many fields. For instance\, Witten’s conjecture regarding intersection numbers on moduli spaces of Riemann surfaces has a fascinating connection to the Weil-Petersson volume\, which motivated Mirzakhani to give a proof via Teichmueller theory\, hyperbolic geometry\, and symplectic geometry. In this talk I will introduce an analogue of Witten’s intersection numbers on moduli spaces of Abelian differentials to compute the Masur-Veech volumes induced by the flat metric associated with Abelian differentials. This is joint work with Moeller\, Sauvaget\, and Zagier (arXiv:1901.01785).\n\n\n\n  \nWednesday\, May 1 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 10:00am\nPavel Etingof\, MIT\nTitle: Short star-products for filtered quantizations \nThis is joint work with Eric Rains and Douglas Stryker.\n\n\n10:00 – 10:30am\nBreak\n\n\n\n10:30 – 11:30am\nRoman Bezrukavnikov\, MIT\nTitle: Stability conditions and representation theory \nAbstract: I will recall the concept of real variation of stabilities (introduced in my work with Anno and Mirkovic)\nand its relation to modular Lie algebra representations. I will also address a potential generalization of that picture\nto modular representations of affine Lie algebras related to the classical limit of geometric Langlands duality and its local counterpart.\n\n\n11:30 – 11:45am\nBreak\n\n\n\n11:45 – 12:45pm\nQile Chen\, BC\nTitle: Counting curves in critical locus via logarithmic compactification \nAbstract: An R-map consists of a pre-stable map to possibly non-GIT quotient together with sections of certain spin bundles. The moduli of R-maps are in general non-compact. When the target of R-maps is equipped with a super-potential W with compact critical locus\, using Kiem-Li cosection localization it has been proved by many authors in various settings that the virtual cycle of R-maps can be represented by the cosection localized virtual cycle which is supported on the proper locus consisting of R-maps in the critical locus of W. Though the moduli of R-maps is equipped with a natural torus action by scaling of the spin bundles\, the non-compactness of the R-maps moduli makes such powerful torus action useless. \nIn this talk\, I will introduce a logarithmic compactification of the moduli of R-maps using certain modifications of stable logarithmic maps. The logarithmic moduli space carries a canonical virtual cycle from the logarithmic deformation theory. In the presence of a super-potential with compact critical locus\, it further carries a reduced virtual cycle. We prove that (1) the reduced virtual cycle of the compactification can be represented by the cosection localized virtual cycle; and (2) the difference of the canonical and reduced virtual cycles is another reduced virtual cycle supported along the logarithmic boundary. As an application\, one recovers the Gromov-Witten invariants of the critical locus as the invariants of logarithmic R-maps of its ambient space in an explicit form. The latter can be calculated using the spin torus action. \nThis is a joint work with Felix Janda and Yongbin Ruan.\n\n\n12:45 – 2:30pm\nLunch\n\n\n\n2:30 – 3:30pm\nSi Li\, Tsinghua\nTitle: Semi-infinite Hodge structure: from BCOV theory to Seiberg-Witten geometry \nAbstract: I will explain how the semi-infinite Hodge theory extends Kodaira-Spencer gravity (Bershadsky-Cecotti-Ooguri-Vafa theory of B-twisted closed topological string field theory) into a full solution of Batalin-Vilkovisky master equation. This allows us to formulate quantum B-model via a rigorous BV quantization method and construct integrable hierarchies arising naturally from the background symmetry. In the second part of the talk\, I will explain the recent discovery of the connection between K.Saito’s primitive form and 4d N=2 Seiberg-Witten geometry arising from singularity theory.\n\n\n3:30 – 4:00pm\nBreak\n\n\n\n4:00 – 5:00pm\nLudmil Katzarkov\, Moscow\nTitle: PDE’s non commutative  motives and HMS. \nAbstract: In this talk we will discuss the theory of central manifolds and the new structures in geometry it produces. Application to Bir.  Geometry will be discussed.\n\n\n\n 
URL:https://cmsa.fas.harvard.edu/event/conference-on-algebraic-geometry-representation-theory-and-mathematical-physics/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/algebraic-geo-conference-final-795x1024-1-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190502T090000
DTEND;TZID=America/New_York:20190505T170000
DTSTAMP:20250328T145104Z
CREATED:20230715T175235Z
LAST-MODIFIED:20250328T145104Z
UID:10000115-1556787600-1557075600@cmsa.fas.harvard.edu
SUMMARY:Conference on Differential Geometry\, Calabi-Yau theory and General Relativity: A conference in honor of the 70th Birthday of Shing-Tung Yau
DESCRIPTION:On May 2-5\, 2019 the Harvard Mathematics Department hosted a Conference on Differential Geometry\, Calabi-Yau Theory and General Relativity: A conference in honor of the 70th Birthday of Shing-Tung Yau. The conference was held in the  Science Center\, Lecture Hall C.  \nOrganizers:\n\nHorng-Tzer Yau (Harvard)\nWilfried Schmid (Harvard)\nClifford Taubes (Harvard)\nCumrun Vafa (Harvard)\n\nSpeakers:\n\nLydia Bieri\, University of Michigan\nTristan Collins\, MIT\nSimon Donaldson\, Imperial College\nFan Chung Graham\, UC San Diego\nNigel Hitchin\, Oxford University\nJun Li\, Stanford University\nKefeng Liu\, UCLA\nChiu-Chu Melissa Liu\, Columbia University\nAlina Marian\, Northeastern University\nXenia de la Ossa\, Oxford University\nDuong H. Phong\, Columbia University\nRichard Schoen\, UC Irvine\nAndrew Strominger\, Harvard University\nNike Sun\, MIT\nClifford Taubes\, Harvard University\nChuu-Lian Terng\, UC Irvine\nValentino Tosatti\, Northwestern University\nKaren Uhlenbeck\, University of Texas\nCumrun Vafa\, Harvard University\nMu Tao Wang\, Columbia University\nEdward Witten\, IAS\nStephen Yau\, Tsinghua University\, P.R. China
URL:https://cmsa.fas.harvard.edu/event/conference-on-differential-geometry-calabi-yau-theory-and-general-relativity-a-conference-in-honor-of-the-70th-birthday-of-shing-tung-yau/
LOCATION:Harvard Science Center\, 1 Oxford Street\, Cambridge\, MA\, 02138
CATEGORIES:Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Yau-2-2-791x1024-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190819T083000
DTEND;TZID=America/New_York:20190820T164000
DTSTAMP:20250328T145128Z
CREATED:20230707T174003Z
LAST-MODIFIED:20250328T145128Z
UID:10000116-1566203400-1566319200@cmsa.fas.harvard.edu
SUMMARY:2019 Big Data Conference
DESCRIPTION:On August 19-20\, 2019 the CMSA hosted the fifth annual Conference on Big Data. The Conference will featured many speakers from the Harvard community as well as scholars from across the globe\, with talks focusing on computer science\, statistics\, math and physics\, and economics. \nThe talks will take place in Science Center Hall D\, 1 Oxford Street. \nVideos can be found in the Youtube playlist.
URL:https://cmsa.fas.harvard.edu/event/2019-big-data-conference/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Big Data Conference,Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Big-Data-2019-Poster-5-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190829T083000
DTEND;TZID=America/New_York:20190831T144500
DTSTAMP:20250328T144206Z
CREATED:20230707T174207Z
LAST-MODIFIED:20250328T144206Z
UID:10000117-1567067400-1567262700@cmsa.fas.harvard.edu
SUMMARY:Workshop on Foundations of Computational Science
DESCRIPTION:On August 29-31\, 2019 the Center of Mathematical Sciences and Applications  hosted a workshop on Foundations of Computational Science. The workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.  This workshop was organized by David Xianfeng Gu. \nSpeakers: \n\nSarah Adel Bargal\, Boston University\nJianfeng Chen\, Harvard\nTat Seng Chua\, National University of Singapore\nKe Deng\, Tsinghua\nDavid Xianfeng Gu\, Stony Brook\nYike Guo\, Imperial College London\nMinlie Huang\, Tsinghua\nScott Kominers\, Harvard\nBrian Kulis\, Boston University\nWee Sun Lee\, National University of Singapore\nQianxiao Li\, National University of Singapore\nHanzhong Liu\, Tsinghua\nJun Liu\, Harvard\nXiao-Li Meng\, Harvard\nCengiz Pehlevan\, Harvard\nDonald Rubin\, Harvard\nSuproteem Sarkar\, Harvard\nZuowei Shen\, National University of Singapore\nYuanchun Shi\, Tsinghua\nJustin Solomon\, MIT\nHang Su\, Tsinghua\nMaosong Sun\, Tsinghua\nMirac Suzgun\, Harvard\nSergiy Verstyuk\, CMSA\nXiaoqin Wang\, Tsinghua\nBin Xu\, Tsinghua\nJun Zhu\, Tsinghua\nWenwu Zhu\, Tsinghua
URL:https://cmsa.fas.harvard.edu/event/workshop-on-foundations-of-computational-science/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/AI-Poster-3.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190910T091500
DTEND;TZID=America/New_York:20190911T152500
DTSTAMP:20250328T144415Z
CREATED:20230707T174623Z
LAST-MODIFIED:20250328T144415Z
UID:10000118-1568106900-1568215500@cmsa.fas.harvard.edu
SUMMARY:Topology and Dynamics in Quantum Matter Workshop
DESCRIPTION:On September 10-11\, 2019\, the CMSA  hosted a second workshop on Topological Aspects of Condensed Matter. \nNew ideas rooted in topology have recently had a major impact on condensed matter physics\, and have led to new connections with high energy physics\, mathematics and quantum information theory.  The aim of this program will be to deepen these connections and spark new progress by fostering discussion and new collaborations within and across disciplines. \nTopics include i) the classification of topological states  ii) topological orders in two and three dimensions including quantum spin liquids\, quantum Hall states and fracton phases and iii)  interplay of symmetry and topology in quantum many body systems\, including symmetry protected topological phases\, symmetry fractionalization and anomalies iv) topological phenomena in quantum systems  driven far from equlibrium v) quantum field theory approaches to topological matter. \nThis workshop is part of the CMSA’s program on Program on Topological Aspects of Condensed Matter\, and is the second of two workshops\, in addition to a visitor program and seminars. \nThe workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nOrganizers: Michael Hermele (CU Boulder) and Ashvin Vishwanath (Harvard) \nPartial list of speakers:\n\nNima Arkani-Hamed\, IAS\nJennifer Cano\, Stony Brook\nMeng Cheng\, Yale\nLukasz Fidkowski\, UW Seattle\nDaniel Freed\, Texas\nJeongwan Haah\, Microsoft Research\nAnton Kapustin\, Caltech\nZohar Komargodski\, SCGP/Stony Brook\nJohn McGreevy\, UC San Diego\nPrineha Narang\, Harvard\nYing Ran\, Boston College\nShinsei Ryu\, Chicago\nCumrun Vafa\, Harvard\nChong Wang\, Perimeter\nZhenghan Wang\, Microsoft Station Q\n\n 
URL:https://cmsa.fas.harvard.edu/event/topology-and-dynamics-in-quantum-matter-workshop-2/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Topology-Poster.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191016T121900
DTEND;TZID=America/New_York:20191018T121900
DTSTAMP:20250328T144653Z
CREATED:20230707T175143Z
LAST-MODIFIED:20250328T144653Z
UID:10000119-1571228340-1571401140@cmsa.fas.harvard.edu
SUMMARY:Noncommutative Analysis\, Computational Complexity\, and Quantum Information
DESCRIPTION:On October 16-18\, 2019 the CMSA hosted a workshop on Noncommutative Analysis\, Computational Complexity\, and Quantum Information. \nThis workshop focuses on linking three different rapidly developing areas: noncommutative real algebraic geometry (RAG)\, theory of computation and quantum information theory. This mix of overlapping but independently developing topics should lead to a stimulating flow of tools and important problems into several disciplines.  Given the different communities there will be an emphasis on tutorials and making the lectures broadly understandable. \nThe workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nOrganizers: Boaz Barak\, Bill Helton\, Pablo Parrilo\, & Tselil Schramm. \nSpeakers:\n\nJason Altschuler\, MIT | Video\nBoaz Barak\, Harvard | Video\nAnkit Garg\, Microsoft Research | Slides | Video\nDavid Gosset\, University of Waterloo | Video\nAram Harrow\, MIT | Video\nIgor Klep\, University of Ljubljana\nSalma Kuhlmann\, Universität Konstanz | Video\nScott McCullough\, University of Florida | Slides\nIon Nechita\, Laboratoire de Physique Théorique | Slides | Video\nRafael Oliveira\, University of Toronto | Video\nVern Paulsen\, University of Waterloo | Video\nSuvrit Sra\, MIT | Video\nVictor Vinnikov\, Ben Gurion University | Video\nJurij Volčič\, Texas A&M University | Slides | Video\nAdam Bene Watts\, MIT
URL:https://cmsa.fas.harvard.edu/event/noncommutative-analysis-computational-complexity-and-quantum-information-2/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Noncommutative-Analysis-Poster-3.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191022T121100
DTEND;TZID=America/New_York:20191022T121100
DTSTAMP:20250328T185250Z
CREATED:20230707T175654Z
LAST-MODIFIED:20250328T185250Z
UID:10000120-1571746260-1571746260@cmsa.fas.harvard.edu
SUMMARY:2019 Ding Shum Lecture
DESCRIPTION:  \nOn October 22\, 2019\, the CMSA held the third annual Ding Shum lecture. \nSpeaker: Ronald L. Rivest (MIT) \nTitle: Election Security \nRonald L. Rivest is an Institute Professor at the Massachusetts Institute of Technology. He is a member of the Electrical Engineering and Computer Science Department and the Computer Science and Artificial Intelligence Laboratory (CSAIL) and a founder of the Cryptography and Information Security research group within CSAIL. His research has been in the areas of algorithms\, machine learning\, cryptography\, and election security\, for which he has received multiple awards\, including: the ACM Turing Award (with Adleman and Shamir)\, the BBVA Frontiers of Knowledge Award\, National Inventor’s Hall of Fame membership\, and the Marconi Prize. \nProf. Rivest is also well-known as a co-author of the textbook “Introduction to Algorithms” (with Cormen\, Leiserson\, and Stein)\, and as a co-inventor of the RSA public-key cryptosystem (with Adleman and Shamir). He is a co-founder of RSA and of Verisign.He has served on the Technical Guidelines Development Committee (advisory to the Election Assistance Commission)\, in charge of the Security subcommittee. He is a member of the CalTech/MIT Voting Technology Project\, on the Board of Verified Voting\, and an advisor to the Electronic Privacy Information Center. Additionally\, he has served on the Technical Guidelines Development Committee (advisory to the Election Assistance Commission)\, as a member of the CalTech/MIT Voting Technology Project\, and as an advisor to the Electronic Privacy Information Center. \n  \n \nLast year featured Eric Maskin\, who spoke on “How to Improve Presidential Elections: the Mathematics of Voting.” The first Ding Shum lecture took place on October 10\, 2017\, featuring Leslie Valiant on “Learning as a Theory of Everything.” \nThis event is made possible by the generous funding of Ding Lei and Harry Shum.\n 
URL:https://cmsa.fas.harvard.edu/event/2019-ding-shum-lecture/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Ding Shum Lecture,Event,Public Lecture,Special Lectures
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/DingShum-2019-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191028T090000
DTEND;TZID=America/New_York:20191030T170000
DTSTAMP:20250327T144000Z
CREATED:20230715T071637Z
LAST-MODIFIED:20250327T144000Z
UID:10000121-1572253200-1572454800@cmsa.fas.harvard.edu
SUMMARY:Spacetime and Quantum Mechanics Master Class Workshop
DESCRIPTION:As part of the program on Spacetime and Quantum Mechanics\, Total Positivity and Motives\, the CMSA will host a “Master Class Workshop”  on October 28-30\, 2019. Each day of the workshop will feature an intensive full day of pedagogical lectures\, with the aim of bringing actively interested but non-expert physicists and mathematicians up to speed on the featured topics. \nEveryone is welcome to attend the lectures. \nThe master class workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nOrganizers: \n\nNima Arkani-Hamed (IAS)\nLauren Williams (Harvard)\nAlex Postnikov (MIT)\nThomas Lam (Michigan)\n\n\nHere is a partial list of the mathematicians and physicists who have indicated that they will attend part or all of this special program as a visitor: \n\nPaolo Benincasa\, 11/17/2019 – 11/29/2019\nJacob Bourjaily\, 9/1/2019 – 12/15/2019\nFrancis Brown\, 9/15/2019 – 9/20/2019\nSimon Caron-Huot\, 9/30/2019 – 10/04/2019\nLance Dixon\, 9/9/2019 – 9/20/2019\nCharles Doran\, 10/19/2019 – 11/1/2019\nJames Drummond\, 10/14/2019 – 10/18/2019\nNick Early\, 11/18/2019 – 11/22/2019\nLivia Ferro\, 10/27/2019 – 11/9/2019\nSergey Fomin\, 10/6/2019 – 10/16/2019\nSebastian Franco\, 10/9/2019 – 10/19/2019\nHadleigh Frost\, 9/15/2019 – 12/20/2019\nMichael Green\, 10/05/2019 – 10/13/2019\nAlexander Goncharov\, 12/05/2019 – 12/20/2019\nSong He\, 9/29/2019 – 11/10/2019\nXuhua He\, 10/30/2019-11/03/2019.\nEnrico Herrmann\, 10/27/2019 – 11/9/2019\nYutin Huang\, 9/30/2019 – 10/12/2019\nSteven Karp\, 10/11/2019 – 11/03/2019\nTomasz Lukowski\, 10/27/2019 – 11/11/2019\nAndrew McLeod\, 10/6/2019 – 10/19/2019 & 11/3/2019 – 11/16/2019\nSebastian Mizera\, 10/28/2019 – 11/1/2019\nErik Panzer\, 9/15/2019 – 9/25/2019\nMatteo Parisi\, 10/26/2019 – 11/10/2019\nJulio Parra-Martinez\, 10/10/2019 – 05/12/2019\n Pierpaolo Mastrolia\, 11/8/2019 – 11/16/2019\nPasha Pylyavskyy\, 9/8/2019 – 9/22/2019 & 10/14/2019 – 11/1/2019\nJunjie Rao\, 10/25/2019 – 11/04/2019\nGiulio Salvatori\, 9/3/2019 – 12/15/2019\nMichael Shapiro\, 10/27/2019 – 11/2/2019\nDavid Speyer\, 10/14/2019 – 10/18/2019\nHugh Thomas\, 10/27/2019 – 11/22/2019\nJaroslav Trnka\, 9/30/2019 – 10/04/2019\, 10/28/2019 – 11/01/2019\, 11/18/2019 – 11/22/2019\nCristian Vergu\, 11/10/2019 – 11/30/2019\nMatthias Volk\, 10/14/2019 – 10/25/2019\nMatthew von Hippel\, 11/11/2019 – 11/22/2019\nPierre Vanhove\, 10/22/2019 – 10/31/2019\nMatthias Wilhelm\, 10/14/2019 – 10/25/2019
URL:https://cmsa.fas.harvard.edu/event/spacetime-and-quantum-mechanics-master-class-workshop/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Space-Time-poster-5.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191101T090000
DTEND;TZID=America/New_York:20191101T170000
DTSTAMP:20250305T211543Z
CREATED:20230715T072841Z
LAST-MODIFIED:20250305T211543Z
UID:10000122-1572598800-1572627600@cmsa.fas.harvard.edu
SUMMARY:Learning from health data in the million genome era
DESCRIPTION:On November 1\, 2019 the CMSA will be hosting a conference organized by Seven Bridges Genomics. The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nProjects currently underway around the world are collecting detailed health and genomic data from millions of volunteers. In parallel\, numerous healthcare systems have announced commitments to integrate genomic data into the standard of care for select patients. These data have the potential to reveal transformative insights into health and disease. However\, to realize this promise\, novel approaches are required across the full life cycle of data analysis. This symposium will include discussion of advanced statistical and algorithmic approaches to draw insights from petabyte scale genomic and health data; success stories to date; and a view towards the future of clinical integration of genomics in the learning health system. \nSpeakers:  \n\nHeidi Rehm\, Ph.D.\nChief Genomics Officer\, MGH; Professor of Pathology\, MGH\, BWH & Harvard Medical School; Medical Director\, Broad Institute Clinical Research Sequencing Platform.\nSaiju Pyarajan\, Ph.D.\nDirector\, Centre for Data and Computational Sciences\,VABHS\, and Department of Medicine\, BWH and HMS\nTianxi Cai\, Sci.D\nJohn Rock Professor of Population and Translational Data Sciences\, Department of Biostatistics\, Harvard School of Public Health\nSusan Redline\, M.D.\, M.P.H\nFarrell Professor of Sleep MedicineHarvard Medical School\, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center\nAvinash Sahu\, Ph.D.\nPostdoctoral Research Fellow\, Dana Farber Cancer Institute\, Harvard School of Public Health\nPeter J. Park\, Ph.D.\nProfessor of Biomedical Informatics\, Department of Biomedical Informatics\, Harvard Medical School\nDavid Roberson\nCommunity Engagement Manager\, Seven Bridges
URL:https://cmsa.fas.harvard.edu/event/learning-from-health-data-in-the-million-genome-era/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/SEVENB0051-POSTER-Harvard-Seminar-REV1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191112T090000
DTEND;TZID=America/New_York:20191114T170000
DTSTAMP:20250305T184034Z
CREATED:20230715T073116Z
LAST-MODIFIED:20250305T184034Z
UID:10000123-1573549200-1573750800@cmsa.fas.harvard.edu
SUMMARY:Workshop on Dynamics\, Randomness\, and Control in Molecular and Cellular Networks
DESCRIPTION:On November 12-14\, 2019 the CMSA will be hosting a workshop on Dynamics\, Randomness\, and Control in Molecular and Cellular Networks. The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nBiological cells are the fundamental units of life\, and predictive modeling of cellular dynamics is essential for understanding a myriad of biological processes and functions. Rapid advances in technologies have made it possible for biologists to measure many variables and outputs from complex molecular and cellular networks with various inputs and environmental conditions. However\, such advances are far ahead of the development of mathematical theory\, models and methods needed to secure a deep understanding of how high-level robust behaviors emerge from the interactions in complex structures\, especially in dynamic and stochastic environments. This workshop will bring together mathematicians and biological scientists involved in developing mathematical theories and methods for understanding\, predicting and controlling dynamic behavior of molecular and cellular networks. Particular emphasis will be placed on efforts directed towards discovering underlying biological principles that govern function\, adaptation and evolution\, and on the development of associated mathematical theories. \nOrganizers: Jeremy Gunawardena (Harvard) and Ruth Williams (University of California\, San Diego) \nSpeakers:  \n\nDavid Anderson\, University of Wisconsin | Slides\nJames Collins\, MIT\nDomitilla Del Vecchio\,  MIT | Slides\nOlga K. Dudko\, UC San Diego\nMassimiliano Esposito\, University of Luxembourg | Slides\nJohn Fricks\, Arizona State University | Slides\nHeather Harrington\, University of Oxford\nJoe Howard\, Yale University\nKrešimir Josić\, University of Houston\nSamuel Kou\, Harvard University\nTom Kurtz\, University of Wisconsin | Slides\nAndrew Murray\, Harvard University\nAntonis Papachristodoulou\, University of Oxford\nJohan Paulsson\, Harvard University\nLea Popovic\, Concordia University\nSharad Ramanathan\, Harvard University\nEduardo Sontag\, Northeastern University\nJörg Stelling\, ETH Zurich | Slides\nPieter Rein ten Wolde\, AMOLF | Slides\n\nVideos from the workshop can be found in the Youtube playlist.
URL:https://cmsa.fas.harvard.edu/event/workshop-on-dynamics-randomness-and-control-in-molecular-and-cellular-networks/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Dynamics-12-x-18-683x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191122T133000
DTEND;TZID=America/New_York:20191123T170000
DTSTAMP:20250305T200026Z
CREATED:20230715T073326Z
LAST-MODIFIED:20250305T200026Z
UID:10000124-1574429400-1574528400@cmsa.fas.harvard.edu
SUMMARY:Current Developments in Mathematics 2019
DESCRIPTION:  \nFriday\, Nov. 22\, 2019 1:30 pm – 5:20 pm \nSaturday\, Nov. 23\, 2019  9:00 am – 5:00 pm \nHarvard University Science Center\, Hall C \nSpeakers: \n·      Svetlana Jitomirskaya (UC Irvine) \n·      Subash Khot (NYU) \n·      Jun Li (Stanford) \n·      André Neves (Chicago) \n·      Geordie Williamson (U Sidney) \nYoutube Playlist \n 
URL:https://cmsa.fas.harvard.edu/event/current-developments-in-mathematics-2019/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CDM-POSTER-2019.email_.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191202T090000
DTEND;TZID=America/New_York:20191204T170000
DTSTAMP:20250305T191848Z
CREATED:20230715T073716Z
LAST-MODIFIED:20250305T191848Z
UID:10000125-1575277200-1575478800@cmsa.fas.harvard.edu
SUMMARY:Quantum Matter Workshop
DESCRIPTION:On December 2-4\, 2019 the CMSA will be hosting a workshop on Quantum Matter as part of our program on Quantum Matter in Mathematics and Physics. The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nPictures can be found here.\n \nOrganizers: Juven Wang (CMSA)\, Xiao-Gang Wen (MIT)\, and Shing-Tung Yau (Harvard) \nConfirmed Speakers:  \n\nZhen Bi\, MIT | Video\nClaudio Chamon\, BU | Video\nTrithep Devakul\, Princeton | Video\nAnushya Chandran\, BU\nLiang Fu\, MIT\nAndrey Gromov\, Brown | Video\nDaniel Louis Jafferis\, Harvard | Video\nEslam Khalaf\, Harvard | Video\nHong Liu\, MIT\nShang Liu\, Harvard | Video\nEmil Prodan\, Yeshiva | Video\nSubir Sachdev\, Harvard | Video\nDries Sels\, Harvard | Video\nYuya Tanizaki\, NCSU | Video\nSenthil Todadri\, MIT | Video\nJuven Wang\, CMSA | Video\nYifan Wang\, CMSA | Video\nXiao-Gang Wen\, MIT\nXueda Wen\, MIT | Video\nXi Yin\, Harvard | Video\nYizhi You\, Princeton | Video\nYunqin Zheng\, Princeton | Video\n\n 
URL:https://cmsa.fas.harvard.edu/event/quantum-matter-workshop/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Quantum-12x18-1-scaled.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200304T090000
DTEND;TZID=America/New_York:20200306T163000
DTSTAMP:20250328T144548Z
CREATED:20230715T073919Z
LAST-MODIFIED:20250328T144548Z
UID:10000126-1583312400-1583512200@cmsa.fas.harvard.edu
SUMMARY:Mirror symmetry\, gauged linear sigma models\, matrix factorizations\, and related topics
DESCRIPTION:On March 4-6\, 2020 the CMSA will be hosting a three-day workshop on Mirror symmetry\, Gauged linear sigma models\, Matrix factorizations\, and related topics as part of the Simons Collaboration on Homological Mirror Symmetry. The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.  \nSpeakers:  \n\nAndrei Căldăraru\, University of Wisconsin\nDavid Favero\, University of Alberta\nElana Kalashnikov\, Harvard University\nTsung-Ju Lee\, CMSA\nConan Leung\, CUHK\nDavid Morrison\, University of California\, Santa Barbara\nMauricio Romo\, YMSC\nYun Shi\, CMSA\nMark Shoemaker\, Colorado State University\nRachel Webb\, University of Michigan\nChris Woodward\, Rutgers University\nGuangbo Xu\, Texas A&M University\nChenglong Yu\, University of Pennsylvania\n\nSchedule \nVideos from the workshop are available in the Youtube playlist.
URL:https://cmsa.fas.harvard.edu/event/mirror-symmetry-gauged-linear-sigma-models-matrix-factorizations-and-related-topics/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Mirror-Symmetry-poster-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200313T140000
DTEND;TZID=America/New_York:20200313T150000
DTSTAMP:20240227T094116Z
CREATED:20230715T074115Z
LAST-MODIFIED:20240227T094116Z
UID:10000127-1584108000-1584111600@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: Shiing-Shen Chern as a Great Geometer of 20th Century
DESCRIPTION:Shing-Tung Yau (Harvard) \nTitle: Shiing-Shen Chern as a Great Geometer of 20th Century \nVideo | Slides | Article
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_yau/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Yaulecture_Poster-pdf.jpeg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200325T100000
DTEND;TZID=America/New_York:20200429T140000
DTSTAMP:20250328T195935Z
CREATED:20230715T074440Z
LAST-MODIFIED:20250328T195935Z
UID:10000128-1585130400-1588168800@cmsa.fas.harvard.edu
SUMMARY:Frontiers in Applied Mathematics and Computation
DESCRIPTION:Together with the School of Engineering and Applied Sciences\, the CMSA will be hosting a lecture series on the Frontiers in Applied Mathematics and Computation. Talks in this series will aim to highlight current research trends at the interface of applied math and computation and will explore the application of these trends to challenging scientific\, engineering\, and societal problems. \nLectures will take place on March 25\, April 1\, and April 29\, 2021. \nSpeakers: \n\nGeorge Biros (U.T. Austin)\nLaura Grigori (INRIA Paris)\nSamory K. Kpotufe (Columbia)\nJonas Martin Peters (University of Copenhagen)\nJoseph M. Teran (UCLA)\n\n\nThe schedule below will be updated as talks are confirmed. \n  \n\n\n\nDate/Time\nSpeaker\nTitle/Abstract\n\n\n\n\n3/25/2021\n10:00 – 11:00am ET\nJoseph M. Teran\nTitle: Affine-Particle-In-Cell with Conservative Resampling and Implicit Time Stepping for Surface Tension Forces \nAbstract: The Particle-In-Cell (PIC) method of Harlow is one of the first and most widely used numerical methods for Partial Differential Equations (PDE) in computational physics. Its relative efficiency\, versatility and intuitive implementation have made it particularly popular in computational incompressible flow\, plasma physics and large strain elastoplasticity. PIC is characterized by its dual particle/grid (Lagrangian/Eulerian) representation of material where particles are generally used to track material transport in a Lagrangian way and a structured Eulerian grid is used to discretize remaining spatial derivatives in the PDE. I will discuss the importance of conserving linear and angular momentum when switching between these two representations and the recent Affine-Particle-In-Cell (APIC) extension to PIC designed for this conservation. I will also discuss a recent APIC technique for discretizing surface tension forces and their linearizations needed for implicit time stepping. This technique is characterized by a novel surface resampling strategy and I will discuss a generalization of the APIC conservation to this setting.\n\n\n4/1/2021\n9:00 – 10:00am ET\nGeorge Biros\nTitle: Inverse biophysical modeling and its application to neurooncology \nAbstract: A predictive\, patient-specific\, biophysical model of tumor growth would be an invaluable tool for causally connecting diagnostics with predictive medicine. For example\, it could be used for tumor grading\, characterization of the tumor microenvironment\, recurrence prediction\, and treatment planning\,  e.g.\, chemotherapy protocol or enrollment eligibility for clinical trials. Such a model also would provide an important bridge between molecular drivers of tumor growth and imaging-based phenotypic signatures\, and thus\,  help identify and quantify mechanism-based associations between these two. Unfortunately\, such a predictive biophysical model does not exist. Existing models undergoing clinical evaluation are too simple–they do not even capture the MRI phenotype. Although many highly complex models have been proposed\, the major hurdle in deploying them clinically is their calibration and validation. \nIn this talk\, I will discuss the challenges related to the calibration and validation of biophysical models\, and in particular the mathematical structure of the underlying inverse problems. I will also present a new algorithm that localizes the tumor origin within a few millimeters.\n\n\n4/1/2021\n10:00 – 11:00am ET\nSamory K. Kpotufe\nTitle: From Theory to Clustering \nAbstract: Clustering is a basic problem in data analysis\, consisting of partitioning data into meaningful groups called clusters. Practical clustering procedures tend to meet two criteria: flexibility in the shapes and number of clusters estimated\, and efficient processing. While many practical procedures might meet either of these criteria in different applications\, general guarantees often only hold for theoretical procedures that are hard if not impossible to implement. A main aim is to address this gap.\nWe will discuss two recent approaches that compete with state-of-the-art procedures\, while at the same time relying on rigorous analysis of clustering. The first approach fits within the framework of density-based clustering\, a family of flexible clustering approaches. It builds primarily on theoretical insights on nearest-neighbor graphs\, a geometric data structure shown to encode local information on the data density. The second approach speeds up kernel k-means\, a popular Hilbert space embedding and clustering method. This more efficient approach relies on a new interpretation – and alternative use – of kernel-sketching as a geometry-preserving random projection in Hilbert space.\nFinally\, we will present recent experimental results combining the benefits of both approaches in the IoT application domain.\nThe talk is based on various works with collaborators Sanjoy Dasgupta\, Kamalika Chaudhuri\, Ulrike von Luxburg\, Heinrich Jiang\, Bharath Sriperumbudur\, Kun Yang\, and Nick Feamster.\n\n\n4/29/2021\n12:00 – 1:00pm ET\nJonas Martin Peters\nTitle: Causality and Distribution Generalization \nAbstract: Purely predictive methods do not perform well when the test distribution changes too much from the training distribution. Causal models are known to be stable with respect to distributional shifts such as arbitrarily strong interventions on the covariates\, but do not perform well when the test distribution differs only mildly from the training distribution. We discuss anchor regression\, a framework that provides a trade-off between causal and predictive models. The method poses different (convex and non-convex) optimization problems and relates to methods that are tailored for instrumental variable settings. We show how similar principles can be used for inferring metabolic networks. If time allows\, we discuss extensions to nonlinear models and theoretical limitations of such methodology.\n\n\n4/29/2021\n1:00 – 2:00pm ET\nLaura Grigori\nTitle: Randomization and communication avoiding techniques for large scale linear algebra \nAbstract: In this talk we will discuss recent developments of randomization and communication avoiding techniques for solving large scale linear algebra operations. We will focus in particular on solving linear systems of equations and we will discuss a randomized process for orthogonalizing a set of vectors and its usage in GMRES\, while also exploiting mixed precision.  We will also discuss a robust multilevel preconditioner that allows to further accelerate solving large scale linear systems on parallel computers.
URL:https://cmsa.fas.harvard.edu/event/frontiers-in-applied-mathematics-and-computation/
LOCATION:Virtual
CATEGORIES:Event,Special Lectures
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CDAM-poster.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200404T150000
DTEND;TZID=America/New_York:20200404T160000
DTSTAMP:20231229T054939Z
CREATED:20230715T081154Z
LAST-MODIFIED:20231229T054939Z
UID:10000129-1586012400-1586016000@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: The ADHM construction of Yang-Mills instantons
DESCRIPTION:Simon Donaldson (Stony Brook) \nTitle: The ADHM construction of Yang-Mills instantons \nAbstract: In 1978 (Physics Letters 65A) Atiyah\, Hitchin\, Drinfeld and Manin (ADHM) described a construction of the general solution of the Yang-Mills instanton equations over the 4-sphere using linear algebra. This was a major landmark in the modern interaction between geometry and physics\,  and the construction has been the scene for much research activity up to the present day. In this lecture we will review the background and the original ADHM proof\,  using Penrose’s twistor theory and results on algebraic vector bundles over projective 3-space. As time permits\, we will also discuss some further developments\, for example\, the work of Nahm on monopoles and connections to Mukai duality for bundles over complex tori. \nVideo | Slides
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_donaldson/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Donaldson-pdf.jpeg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200415T080000
DTEND;TZID=America/New_York:20200415T090000
DTSTAMP:20231229T055314Z
CREATED:20230715T081655Z
LAST-MODIFIED:20231229T055314Z
UID:10000130-1586937600-1586941200@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: Why do some universities have separate departments of statistics?
DESCRIPTION:Donald Rubin (Harvard) \nTitle: Why do some universities have separate departments of statistics? And are they all anachronisms\, destined to follow the path of other dinosaurs? \nVideo | Slides
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_rubin/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture-Series-Don-pdf.jpeg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200504T130000
DTEND;TZID=America/New_York:20200504T140000
DTSTAMP:20250409T192434Z
CREATED:20230715T081933Z
LAST-MODIFIED:20250409T192434Z
UID:10000131-1588597200-1588600800@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture:  Rationality questions in algebraic geometry
DESCRIPTION:Joe Harris (Harvard) \nTitle: Rationality questions in algebraic geometry \nAbstract: Over the course of the history of algebraic geometry\, rationality questions — motivated by both geometric and arithmetic problems — have often driven the subject forward. The rationality or irrationality of cubic hypersurfaces in particular have led to the development of abelian integrals (dimension one)\, birational geometry (dimension two) and Hodge theory (dimension 3). But there remained much we didn’t understand about the condition of rationality\, such as how it behaves in families. However\, there has been recent progress: work of Hassett\, Tschinkel\, Pirutka and others\, working with examples in dimension 4\, showed that it is in general neither an open condition nor a closed one\, but does behave well with respect to specialization. In this talk I’ll try to give an overview of the history of rationality and the current state of our knowledge. \nVideo
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_harris/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series,Special Lectures
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Harris_updated-pdf.jpeg
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200504T150000
DTEND;TZID=America/New_York:20200504T160000
DTSTAMP:20240227T092426Z
CREATED:20230715T081344Z
LAST-MODIFIED:20240227T092426Z
UID:10000133-1588604400-1588608000@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: Quantum Groups
DESCRIPTION:Pavel Etingof (MIT) \nTitle: Quantum Groups \nAbstract: The theory of quantum groups developed in mid 1980s from attempts to construct and understand solutions of the quantum Yang-Baxter equation\, an important equation arising in quantum field theory and statistical mechanics. Since then\, it has grown into a vast subject with profound connections to many areas of mathematics\, such as representation theory\, the Langlands program\, low-dimensional topology\, category theory\, enumerative geometry\, quantum computation\, algebraic combinatorics\, conformal field theory\, integrable systems\, integrable probability\, and others. I will review some of the main ideas and examples of quantum groups and try to briefly describe some of the applications. \nVideo | Slides
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_etingof/
LOCATION:Virtual
CATEGORIES:Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Etingof-pdf.jpeg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200505T110000
DTEND;TZID=America/New_York:20200505T120000
DTSTAMP:20240227T093025Z
CREATED:20230715T082325Z
LAST-MODIFIED:20240227T093025Z
UID:10000132-1588676400-1588680000@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: Black Hole Formation
DESCRIPTION:Lydia Bieri (University of Michigan) \nTitle: Black Hole Formation \nAbstract: Can black holes form through the focusing of gravitational waves? This was an outstanding question since the early days of general relativity. In his breakthrough result of 2008\, Demetrios Chrstodoulou answered this question with “Yes!” In order to investigate this result\, we will delve deeper into the dynamical mathematical structures of the Einstein equations. Black holes are related to the presence of trapped surfaces in the spacetime manifold. Christodoulou proved that in the regime of pure general relativity and for arbitrarily dispersed initial data\, trapped surfaces form through the focusing of gravitational waves provided the incoming energy is large enough in a precisely defined way. The proof combines new ideas from geometric analysis and nonlinear partial differential equations as well as it introduces new methods to solve large data problems. These methods have many applications beyond general relativity. D. Christodoulou’s result was generalized in various directions by many authors. It launched mathematical activities going into multiple fields in mathematics and physics. In this talk\, we will discuss the mathematical framework of the above question. Then we will outline the main ideas of Christodoulou’s result and its generalizations\, show relations to other questions and give an overview of implications in other fields. \nVideo
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_bieri/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Bieri-pdf.jpeg
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200506T130000
DTEND;TZID=America/New_York:20200506T140000
DTSTAMP:20250328T201043Z
CREATED:20230715T082607Z
LAST-MODIFIED:20250328T201043Z
UID:10000134-1588770000-1588773600@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: My life and times with the sporadic simple groups
DESCRIPTION:Robert Griess (University of Michigan) \nTitle: My life and times with the sporadic simple groups \nAbstract: Five sporadic simple groups were proposed in 19th century and 21 additional ones arose during the period 1965-1975. There were many discussions about the nature of finite simple groups and how sporadic groups are placed in mathematics. While in mathematics grad school at University of Chicago\,  I became fascinated with the unfolding story of sporadic simple groups. It involved theory\, detective work and experiments. During this lecture\, I will describe some of the people\, important ideas and evolution of thinking about sporadic simple groups. Most should be accessible to a general mathematical audience. \nVideo | Slides
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_griess/
LOCATION:Virtual
CATEGORIES:Math Science Literature Lecture Series,Public Lecture,Special Lectures
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Griess-pdf.jpeg
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200522T123000
DTEND;TZID=America/New_York:20200522T133000
DTSTAMP:20240227T091238Z
CREATED:20230715T082921Z
LAST-MODIFIED:20240227T091238Z
UID:10000135-1590150600-1590154200@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: From string theory and Moonshine to vertex algebras
DESCRIPTION:Bong Lian (Brandeis) \nTitle: From string theory and Moonshine to vertex algebras \nAbstract: This is a brief survey of the early historical development of vertex algebras\, beginning in the seventies from Physics and Representation Theory. We shall also discuss some of the ideas that led to various early formulations of the theory’s foundation\, and their relationships\, as well as some of the subsequent and recent developments. The lecture is aimed at a general audience. \nSlides | Video
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_lian/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Lian-pdf.jpeg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200522T123000
DTEND;TZID=America/New_York:20200522T133000
DTSTAMP:20240209T054130Z
CREATED:20230715T083128Z
LAST-MODIFIED:20240209T054130Z
UID:10000136-1590150600-1590154200@cmsa.fas.harvard.edu
SUMMARY:CMSA Math-Science Literature Lecture: Four-dimensional topology
DESCRIPTION:Ciprian Manolescu (Stanford) \nTitle: Four-dimensional topology \nAbstract: I will outline the history of four-dimensional topology. Some major events were the work of Donaldson and Freedman from 1982\, and the introduction of the Seiberg-Witten equations in 1994. I will discuss these\, and then move on to what has been done in the last 20 years\, when the focus shifted to four-manifolds with boundary and cobordisms. Floer homology has led to numerous applications\, and recently there have also been a few novel results (and proofs of old results) using Khovanov homology. The talk will be accessible to a general mathematical audience. \nVideo
URL:https://cmsa.fas.harvard.edu/event/cmsa-math-science-literature-lecture_manolescu/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Lecture_Manolescu-pdf.jpeg
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200824T100000
DTEND;TZID=America/New_York:20200825T140500
DTSTAMP:20250305T185337Z
CREATED:20230707T104105Z
LAST-MODIFIED:20250305T185337Z
UID:10000137-1598263200-1598364300@cmsa.fas.harvard.edu
SUMMARY:2020 Big Data Conference (Virtual)
DESCRIPTION:On August 24-25\, 2020 the CMSA hosted our sixth annual Conference on Big Data. The Conference featured many speakers from the Harvard community as well as scholars from across the globe\, with talks focusing on computer science\, statistics\, math and physics\, and economics. The 2020 Big Data Conference took place virtually. \n\nVideos of the talks are available in this youtube playlist.\n  \nOrganizers:  \n\nShing-Tung Yau\, William Caspar Graustein Professor of Mathematics\, Harvard University\nScott Duke Kominers\, MBA Class of 1960 Associate Professor\, Harvard Business\nHorng-Tzer Yau\, Professor of Mathematics\, Harvard University\nSergiy Verstyuk\, CMSA\, Harvard University\n\nSpeakers:\n \n\nSanjeev Arora\, Princeton University\nJuan Camilo Castillo\, University of Pennsylvania\nJoseph Dexter\, Dartmouth College\nNicole Immorlica\, Microsoft\nAmin Saberi\, Stanford University\nVira Semenova\, University of California\, Berkeley\nVarda Shalev\, Tel Aviv University
URL:https://cmsa.fas.harvard.edu/event/2020-big-data-conference-virtual/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Big Data Conference,Conference,Event
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Big-Data-2020-pdf.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200902T103000
DTEND;TZID=America/New_York:20220202T120000
DTSTAMP:20240131T002143Z
CREATED:20240124T081657Z
LAST-MODIFIED:20240131T002143Z
UID:10001334-1599042600-1643803200@cmsa.fas.harvard.edu
SUMMARY:Strongly Correlated Quantum Materials and High-Temperature Superconductors Series
DESCRIPTION:In the 2020-2021 academic year\, the CMSA will be hosting a lecture series on Strongly Correlated Materials and High Tc Superconductor. All talks will take place from 10:30-12:00pm ET virtually on Zoom. \nCuprate high-temperature superconductors are a classic quantum material system to demonstrate the beauty of “Emergence and Entanglement” in the quantum phases of matter. Merely by adding more holes into an antiferromagnetic insulator\, several fascinating phases emerge\, including a d-wave superconductor\, a pseudo-gap metal\, and strange metal. After intensive studies from experimental\, theoretical\, and numerical communities for more than three decades\, remarkable progress has been made\, but basic questions remain: \n\nWhat is the origin of the superconductivity? What are the relative contributions of electron-phonon coupling\, spin fluctuations\, or resonating-valence-bonds?\nHow do we explain the pseudo-gap and the Fermi arc in the underdoped region above the critical temperature? Are they from some symmetry breaking order parameters\, or do we need an unconventional picture involving fractionalization?\nIs the strange metal at optimal doping associated with a quantum critical point? And if so\, what is the driving force of this phase transition?\n\nThe cuprate quantum materials have been a major source for many new concepts in modern condensed matter physics\, such as quantum spin liquids\, topological order\, and non-Fermi liquids. In the coming years\, it is clear that the study of the cuprates will continually motivate new concepts and development of new techniques. In this seminar series\, we hope to accelerate this process by bringing together deeper conversations between experimental\, theoretical\, and numerical experts with different backgrounds and perspectives. \nThe Strongly Correlated Quantum Materials and High-Temperature Superconductors series is a part of the Quantum Matter in Mathematics and Physics seminar. \nSeminar organizers: Juven Wang (Harvard CMSA) and Yahui Zhang (Harvard). \nScientific program advisors: Professor Subir Sachdev (Harvard)\, Professor Patrick Lee (MIT). \nIn order to learn how to attend this series\, please fill out this form. \nFor more information\, please contact Juven Wang (jw@cmsa.fas.harvard.edu) and Yahui Zhang (yahui_zhang@g.harvard.edu) \nSpring 2022\nApril 20\, 2022 | 11:30 – 1:00 pm ET \nHarold Y. Hwang (Stanford University & SLAC National Accelerator Laboratory) \nTitle: Superconductivity in infinite-layer nickelates \nAbstract: Since its discovery\, unconventional superconductivity in cuprates has motivated the search for materials with analogous electronic or atomic structure. We have used soft chemistry approaches to synthesize superconducting infinite layer nickelates from their perovskite precursor phase. We will present the synthesis and transport properties of the nickelates\, observation of a doping-dependent superconducting dome\, and our current understanding of their electronic and magnetic structure. \n\nFebruary 3\, 2022 | 11:30 – 1:00 pm ET \nLu Li (U Michigan) \nTitle: Quantum Oscillations of Electrical Resistivity in an Insulator \nAbstract: In metals\, orbital motions of conduction electrons are quantized in magnetic fields\, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators\, in which all the electrons are localized. Here we report a notable exception in an insulator — ytterbium dodecaboride (YbB12). The resistivity of YbB12\, despite much larger than that of usual metals\, exhibits profound quantum oscillations under intense magnetic fields. This unconventional oscillation is shown to arise from the insulating bulk instead of conducting surface states. The large effective masses indicate strong correlation effects between electrons. Our result is the first discovery of quantum oscillations in the electrical resistivity of a strongly correlated insulator and will bring crucial insight into understanding the ground state in gapped Kondo systems. \n2020 – 2021\nSeptember 2\, 2020 | 10:30am ET\n\n\n\n\n\n\n\nSubir Sachdev (Harvard) \nTitle: Metal-to-metal quantum phase transitions not described by symmetry-breaking orders \nAbstract: Numerous experiments have explored the phases of the cuprates with increasing doping density p from the antiferromagnetic insulator. There is now strong evidence that the small p region is a novel phase of matter\, often called the pseudogap metal\, separated from conventional Fermi liquid at larger p by a quantum phase transition. Symmetry-breaking orders play a spectator role\, at best\, at this quantum phase transition. I will describe trial wavefunctions across this metal-metal transition employing hidden layers of ancilla qubits (proposed by Ya-Hui Zhang). Quantum fluctuations are described by a gauge theory  of ghost fermions that carry neither spin nor charge. I will also\ndescribe a separate approach to this transition in a t-J model with random exchange interactions in the limit of large dimensions. This approach leads to a partly solvable SYK-like critical theory of holons and spinons\, and a linear in temperature resistivity from time reparameterization fluctuations. Near criticality\, both approaches have in common emergent fractionalized excitations\, and a significantly larger entropy than naively expected. \nVideo\n\n\n\n\nSeptember 23\, 2020 | 10:30am ET\n\n\n\n\n\n\n\nSubir Sachdev (Harvard) \nTitle: Metal-to-metal quantum phase transitions not described by symmetry-breaking orders II \nAbstract: In this second talk\, I will focus on (nearly) solvable models of metal-metal transition in random systems. The t-J model with random and all-to-all hopping and exchange can be mapped onto a quantum impurity model coupled self-consistently to an environment (the mapping also applies to a t-J model in a large dimension lattice\,  with random nearest-neighbor exchange). Such models will be argued to exhibit metal-metal quantum phase transitions in the universality class of the SYK model\, accompanied by a linear-in-T resistivity from time reparameterization  fluctuations. I will also present the results of exact diagonalization of random t-J clusters\, obtained recently with Henry Shackleton\, Alexander Wietek\, and Antoine Georges. \nVideo\n\n\n\n\nSeptember 24\, 2020 | 12:00pm ET\n\n\n\n\n\n\n\nInna Vishik (University of California\, Davis)\n\nTitle: Universality vs materials-dependence in cuprates: ARPES studies of the model cuprate Hg1201Abstract: The cuprate superconductors exhibit the highest ambient-pressure superconducting transition temperatures (T c )\, and after more than three decades of extraordinary research activity\, continue to pose formidable scientific challenges. A major experimental obstacle has been to distinguish universal phenomena from materials- or technique-dependent ones. Angle-resolved photoemission spectroscopy (ARPES) measures momentum-dependent single-particle electronic excitations and has been invaluable in the endeavor to determine the anisotropic momentum-space properties of the cuprates. HgBa 2 CuO 4+d (Hg1201) is a single-layer cuprate with a particularly high optimal T c and a simple crystal structure; yet there exists little information from ARPES about the electronic properties of this model system. I will present recent ARPES studies of doping-\, temperature-\, and momentum-dependent systematics of near-nodal dispersion anomalies in Hg1201. The data reveal a hierarchy of three distinct energy scales which establish several universal phenomena\, both in terms of connecting multiple experimental techniques for a single material\, and in terms of connecting comparable spectral features in multiple structurally similar cuprates.Video\n\n\n\n\nOctober 15\, 2020 | 10:30am ET\n\n\n\n\n\n\n\nLouis Taillefer (Université de Sherbrooke) \nTitle: New signatures of the pseudogap phase of cuprate superconductors \nAbstract: The pseudogap phase of cuprate superconductors is arguably the most enigmatic phase of quantum matter. We aim to shed new light on this phase by investigating the non- superconducting ground state of several cuprate materials at low temperature across a wide doping range\, suppressing superconductivity with a magnetic field. Hall effect measurements across the pseudogap critical doping p* reveal a sharp drop in carrier density n from n = 1 + p above p* to n = p below p\, signaling a major transformation of the Fermi surface. Angle-dependent magneto-resistance (ADMR) directly reveals a change in Fermi surface topology across p. From specific heat measurements\, we observe the classic thermodynamic signatures of quantum criticality: the electronic specific heat C el shows a sharp peak at p\, where it varies in temperature as C el ~ – T logT. At p and just above\, the electrical resistivity is linear in T at low T\, with an inelastic scattering rate that obeys the Planckian limit. Finally\, the pseudogap phase is found to have a large negative thermal Hall conductivity\, which extends to zero doping. We show that the pseudogap phase makes phonons become chiral. Understanding the mechanisms responsible for these various new signatures will help elucidate the nature of the pseudogap phase. \nVideo\n\n\n\n\nOctober 28\, 2020 | 10:30am ET\n\n\n\n\n\n\n\nPatrick Lee (MIT) \nTitle: The not-so-normal normal state of underdoped Cuprate \nAbstract: The underdoped Cuprate exhibits a rich variety of unusual properties that have been exposed after years of experimental investigations. They include a pseudo-gap near the anti-nodal points and “Fermi arcs” of gapless excitations\, together with a variety of order such as charge order\, nematicity and possibly loop currents and time reversal and inversion breaking. I shall argue that by making a single assumption of strong pair fluctuations at finite momentum (Pair density wave)\, a unified description of this phenomenology is possible. As an example\, I will focus on a description of the ground state that emerges when superconductivity is suppressed by a magnetic field which supports small electron pockets. [Dai\, Senthil\, Lee\, Phys Rev B101\, 064502 (2020)] There is some support for the pair density wave hypothesis from STM data that found charge order at double the usual wave-vector in the vicinity of vortices\, as well as evidence for a fragile form of superconductivity persisting to fields much above Hc2. I shall suggest a more direct experimental probe of the proposed fluctuating pair density wave. \nVideo\n\n\n\n\nNovember 6\, 2020 |12:30pm ET\n\n\n\n\n\n\n\nZhi-Xun Shen (Stanford University) \nTitle: Essential Ingredients for Superconductivity in Cupper Oxide Superconductors \nAbstract: High‐temperature superconductivity in cupper oxides\, with critical temperature well above what wasanticipated by the BCS theory\, remains a major unsolved physics problem. The problem is fascinating because it is simultaneously simple ‐ being a single band and 1⁄2 spin system\, yet extremely rich ‐ boasting d‐wave superconductivity\, pseudogap\, spin and charge orders\, and strange metal phenomenology. For this reason\, cuprates emerge as the most important model system for correlated electrons – stimulating conversations on the physics of Hubbard model\, quantum critical point\, Planckian metal and beyond.\nCentral to this debate is whether the Hubbard model\, which is the natural starting point for the undoped\nmagnetic insulator\, contains the essential ingredients for key physics in cuprates. In this talk\, I will discuss our photoemission evidence for a multifaceted answer to this question [1‐3]. First\, we show results that naturally points to the importance of Coulomb and magnetic interactions\, including d‐wave superconducting gap structure [4]\, exchange energy (J) control of bandwidth in single‐hole dynamics [5]. Second\, we evidence effects beyond the Hubbard model\, including band dispersion anomalies at known phonon frequencies [6\, 7]\, polaronic spectral lineshape and the emergence of quasiparticle with doping [8]. Third\, we show properties likely of hybrid electronic and phononic origin\, including the pseudogap [9‐11]\, and the almost vertical phase boundary near the critical 19% doping [12]. Fourth\, we show examples of small q phononic coupling that cooperates with d‐wave superconductivity [13‐15]. Finally\, we discuss recent experimental advance in synthesizing and investigating doped one‐dimensional (1D) cuprates [16]. As theoretical calculations of the 1D Hubbard model are reliable\, a robust comparison can be carried out. The experiment reveals a near‐neighbor attractive interaction that is an order of magnitude larger than the attraction generated by spin‐superexchange in the Hubbard model. Addition of such an attractive term\, likely of phononic origin\, into the Hubbard model with canonical parameters provides a quantitative explanation for all important experimental observable: spinon and holon dispersions\, and holon‐ holon attraction. Given the structural similarity of the materials\, It is likely that an extended two‐dimensional\n(2D) Hubbard model with such an attractive term\, will connect the dots of the above four classes of\nexperimental observables and provide a holistic understanding of cuprates\, including the elusive d‐wave superconductivity in 2D Hubbard model. \n[1] A. Damascelli\, Z. Hussain\, and Z.‐X. Shen\, Review of Modern Physics\, 75\, 473 (2003)\n[2] M. Hashimoto et al.\, Nature Physics 10\, 483 (2014)\n[3] JA Sobota\, Y He\, ZX Shen ‐ arXiv preprint arXiv:2008.02378\, 2020; submitted to Rev. of Mod. Phys.\n[4] Z.‐X. Shen et al.\, Phys. Rev. Lett. 70\, 1553 (1993)\n[5] B.O. Wells et al.\, Phys. Rev. Lett. 74\, 964 (1995)\n[6] A. Lanzara et al.\, Nature 412\, 510 (2001)\n[7] T. Cuk et al.\, Phys. Rev. Lett.\, 93\, 117003 (2004)\n[8] K.M. Shen et al.\, Phys. Rev. Lett.\, 93\, 267002 (2004)\n[9] D.M. King et al.\, J. of Phys. & Chem of Solids 56\, 1865 (1995)\n[10] D.S. Marshall et al.\, Phy. Rev. Lett. 76\, 484 (1996)\n[11] A.G. Loeser et al.\, Science 273\, 325 (1996)\n[12] S. Chen et al.\, Science\, 366\, 6469 (2019)\n[13] T.P. Devereaux\, T. Cuk\, Z.X. Shen\, N. Nagaosa\, Phys. Rev. Lett.\, 93\, 117004 (2004)\n[14] S. Johnston et al.\, Phys. Rev. Lett. 108\, 166404 (2012)\n[15] Yu He et al.\, Science\, 362\, 62 (Oct. 2018)\n[16] Z. Chen\, Y. Wang et al.\, preprint\, 2020 \nVideo\n\n\n\n\nNovember 12\, 2020 |10:30am ET\n\n\n\n\n\n\n\nChandra Varma (Visting Professor\, University of California\, Berkeley.\nEmeritus Distinguished Professor\, University of California\, Riverside.)Title: Loop-Current Order and Quantum-Criticality in CupratesThis talk is organized as follows:\n1. Physical Principles leading to Loop-current order and quantum criticality as the central feature in the physics of Cuprates.\n2. Summary of the essentially exact solution of the dissipative xy model for Loop-current fluctuations.\n3. Quantitative comparison of theory for the quantum-criticality with a variety of experiments.\n4. Topological decoration of loop-current order to understand ”Fermi-arcs” and small Fermi-surface magneto-oscillations.Time permitting\,\n(i) Quantitative theory and experiment for fluctuations leading to d-wave superconductivity.\n(ii) Extensions to understand AFM quantum-criticality in heavy-fermions and Fe-based superconductors.\n(iii) Problems.Video\n\n\n\n\nNovember 18\, 2020 |10:30am ET\n\n\n\n\n\n\n\nAntoine Georges (Collège de France\, Paris and Flatiron Institute\, New York) \nTitle: Superconductivity\, Stripes\, Antiferromagnetism and the Pseudogap: What Do We Know Today about the 2D Hubbard model? \nAbstract: Simplified as it is\, the Hubbard model embodies much of the complexity of the `strong correlation problem’ and has established itself as a paradigmatic model in the field. In this talk\, I will argue that several key aspects of its physics in two dimensions can now be established beyond doubt\, thanks to the development of controlled and accurate computational methods. These methods implement different and complementary points of view on the quantum many-body problem. Along with pushing forward each method\, the community has recently embarked into a major effort to combine and critically compare these approaches\, and in several instances a consistent picture of the physics has emerged as a result. I will review in this perspective our current understanding of the emergence of a pseudogap in both the weak and strong coupling regimes. I will present recent progress in understanding how the pseudogap phase may evolve into a stripe-dominated regime at low temperature\, and briefly address the delicate question of the competition between stripes and superconductivity. I will also emphasize outstanding questions which are still open\, such as the possibility of a Fermi surface reconstruction without symmetry breaking. Whenever possible\, connections to the physics of cuprate superconductors will be made. If time permits\, I may also address the question of Planckian transport and bad metallic transport at high temperature. \nVideo\n\n\n\n\nNovember 19\, 2020 |10:30am ET\n\n\n\n\n\n\n\nEduardo Fradkin (University of Illinois at Urbana-Champaign) \nTitle: Pair Density Waves and Intertwined Orders in High Tc Superconductors\n\nAbstract: I will argue that the orders that are present in high temperature superconductors naturally arise with the same strength and are better regarded as intertwined rather than competing. I illustrate this concept in the context of the orders that are present in the pair-density-wave state and the phase diagrams that result from this analysis. \nVideo\n\n\n\n\nNovember 25\, 2020 |10:30am ET\n\n\n\n\n\n\n\nQimiao Si (Rice University) \nTitle: Bad Metals and Electronic Orders – Nematicity from Iron Pnictides to Graphene Moiré Systems \nAbstract: Strongly correlated electron systems often show bad-metal behavior\, as operationally specified in terms of a resistivity at room temperature that reaches or exceeds the Mott-Ioffe-Regel limit. They display a rich landscape of electronic orders\, which provide clues to the underlying microscopic physics. Iron-based superconductors present a striking case study\, and have been the subject of extensive efforts during the past decade or so. They are well established to be bad metals\, and their phase diagrams prominently feature various types of electronic orders that are essentially always accompanied by nematicity. In this talk\, I will summarize these characteristic features and discuss our own efforts towards understanding the normal state through the lens of the electronic orders and their fluctuations. Implications for superconductivity will be briefly discussed. In the second part of the talk\, I will consider the nematic correlations that have been observed in the graphene-based moiré narrow-band systems. I will present a theoretical study which demonstrates nematicity in a “fragile insulator”\, predicts its persistence in the bad metal regime and provides an overall perspective on the phase diagram of these correlated systems.\n\n\n\n\nDecember 2\, 2020 |10:30am ET\n\n\n\n\n\n\n\nAndrey Chubukov (University of Minnesota) \nTitle: Interplay between superconductivity and non-Fermi liquid at a quantum critical point in a metal \n\nAbstract:  I discuss the interplay between non-Fermi liquid behaviour and pairing near a quantum-critical point (QCP) in a metal. These tendencies are intertwined in the sense that both originate from the same interaction mediated by gapless fluctuations of a critical order parameter. The two tendencies compete because fermionic incoherence destroys the Cooper logarithm\, while the pairing eliminates scattering at low energies and restores fermionic coherence. I discuss this physics for a class of models with an effective dynamical interaction V (Ω) ~1/|Ω|^γ (the γ-model). This model describes\, in particular\, the pairing at a 2D Ising-nematic critical point in (γ=1/3)\, a 2D antiferromagnetic critical point (γ=1/2) and the pairing by an Einstein phonon with vanishing dressed Debye frequency (γ=2). I argue the pairing wins\, unless the pairing component of the interaction is artificially reduced\, but because of fermionic incoherence in the normal state\, the system develops a pseudogap\, preformed pairs behaviour in the temperature range between the onset of the pairing at Tp and the onset of phase coherence at the actual superconducting Tc. The ratio Tc/Tp decreases with γ and vanishes at γ =2. I present two complementary arguments of why this happens. One is the softening of longitudinal gap fluctuations\, which become gapless at γ =2. Another is the emergence of a 1D array of dynamical vortices\, whose number diverges at γ =2. I argue that once the number of vortices becomes infinite\, quasiparticle energies effectively get quantized and do not get re-arranged in the presence of a small phase variation. I show that a new non-superconducting ground state emerges at γ >2.\n\n\n\n\nDecember 9\, 2020 |10:30am ET\n\n\n\n\n\n\n\nDavid Hsieh (Caltech) \nTitle:  Signatures of anomalous symmetry breaking in the cuprates   \nAbstract: The temperature versus doping phase diagram of the cuprate high-Tc superconductors features an enigmatic pseudogap region whose microscopic origin remains a subject of intensive study. Experimentally resolving its symmetry properties is imperative for narrowing down the list of possible explanations. In this talk I will give an overview of how optical second harmonic generation (SHG) can be used as a sensitive probe of symmetry breaking\, and recap the ways it has been used to solve outstanding problems in condensed matter physics. I will then describe how we have been applying SHG polarimetry and spectroscopy to interrogate the cuprate pseudogap. In particular\, I will discuss our data on YBa2Cu3Oy [1]\, which show an order parameter-like increase in SHG intensity below the pseudogap temperature T* across a broad range of doping levels. I will then focus on our more recent results on a model parent cuprate Sr2CuO2Cl2 [2]\, where evidence of anomalous broken symmetries surprisingly also exists. Possible connections between these observations will be speculated upon.\n[1] L. Zhao\, C. A. Belvin\, R. Liang\, D. A. Bonn\, W. N. Hardy\, N. P. Armitage and D. Hsieh\, “A global inversion-symmetry-broken phase inside the pseudogap region of YBa2Cu3Oy\,” Nature Phys. 13\, 250 (2017). \n[2] A. de la Torre\, K. L. Seyler\, L. Zhao\, S. Di Matteo\, M. S. Scheurer\, Y. Li\, B. Yu\, M. Greven\, S. Sachdev\, M. R. Norman and D. Hsieh. “Anomalous mirror symmetry breaking in a model insulating cuprate Sr2CuO2Cl2\,” Preprint at https://arxiv.org/abs/2008.06516\n\n\n\n\nDecember 16\, 2020 |10:30am ET\n\n\n\n\n\n\n\nZheng-Yu Weng (Tsinghua University) \nTitle: Organizing Principle of Mottness and Complex Phenomenon in High Temperature Superconductors\n\nAbstract: The complex phenomenon in the high-Tc cuprate calls for a microscopic understanding based on general principles. In this Lecture\, an exact organizing principle for a typical doped Mott insulator will be presented\, in which the fermion sign structure is drastically reduced to a mutual statistics. Its nature as a long-range spin-charge entanglement of many-body quantum mechanics will be exemplified by exact numerical calculations. The phase diagram of the cuprate may be unified in a “bottom-up” fashion by a “parent” ground state ansatz with hidden orders constructed based on the organizing principle. Here the pairing mechanism will go beyond the “RVB” picture and the superconducting state is of non-BCS nature with modified London equation and novel elementary excitations. In particular\, the Bogoliubov/Landau quasiparticle excitation are emerging with a two-gap structure in the superconducting state and the Fermi arc in a pseudogap regime. A mathematic framework of fractionalization and duality transformation guided by the organizing principle will be introduced to describe the above emergent phenomenon.\n\n\n\n\nDecember 17\, 2020 |10:30am ET\n\n\n\n\n\n\n\nSteven Kivelson (Stanford University) \nTitle: What do we know about the essential physics of high temperature superconductivity after one third of a century? \nAbstract: Despite the fact that papers submitted to glossy journals universally start by bemoaning the absence of theoretical understanding\, I will argue that the answer to the title question is “quite a lot.” To focus the discussion\, I will take the late P.W. Anderson’s “Last Words on the Cuprates” (arXiv:1612.03919) as a point of departure\, although from a perspective that differs from his in many key points.\n\n\n\n\nJanuary 20\, 2021 |10:30am ET\n\n\n\n\n\n\n\nThomas Peter Devereaux (Stanford University) \nTitle:  Numerical investigations of models of the cuprates\n\nAbstract: Richard Feynman once said “Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach\, these people are the failures in this field. . . ” \nI will summarize efforts to solve microscopic models of the cuprates using quantum Monte Carlo and density matrix renormalization group computational methods\, with emphasis on how far one can get before failing to describe the real materials. I will start with an overview of the quantum chemistry of the cuprates that guides our choices of models\, and then I will discuss “phases” of these models\, both realized and not. I will lastly discuss the transport properties of the models in the “not-so-normal” regions of the phase diagram.\n\n\n\n\nFebruary 3\, 2021 |10:30am ET\n\n\n\n\n\n\n\nPhilip Phillips (University of Illinois Urbana-Champaign) \nTitle: Beyond BCS: An Exact Model for Superconductivity and Mottness\n\nAbstract: High-temperature superconductivity in the cuprates remains an unsolved problem because the cuprates start off their lives as Mott insulators in which no organizing principle such a Fermi surface can be invoked to treat the electron interactions. Consequently\, it would be advantageous to solve even a toy model that exhibits both Mottness and superconductivity. Part of the problem is that the basic model for a Mott insulator\, namely the Hubbard model is unsolvable in any dimension we really care about. To address this problem\, I will start by focusing on the overlooked Z_2 emergent symmetry of a Fermi surface first noted by Anderson and Haldane. Mott insulators break this emergent symmetry. The simplest model of this type is due to Hatsugai/Kohmoto. I will argue that this model can be thought of a fixed point for Mottness. I will then show exactly[1] that this model when appended with a weak pairing interaction exhibits not only the analogue of Cooper’s instability but also a superconducting ground state\, thereby demonstrating that a model for a doped Mott insulator can exhibit superconductivity. The properties of the superconducting state differ drastically from that of the standard BCS theory. The elementary excitations of this superconductor are not linear combinations of particle and hole states but rather are superpositions of doublons and holons\, composite excitations signaling that the superconducting ground state of the doped Mott insulator inherits the non-Fermi liquid character of the normal state. Additional unexpected features of this model are that it exhibits a superconductivity-induced transfer of spectral weight from high to low energies and a suppression of the superfluid density as seen in the cuprates.\n[1] PWP\, L. Yeo\, E. Huang\, Nature Physics\, 16\, 1175-1180 (2020).\n\n\n\n\nFebruary 10\, 2021 |10:30am ET\n\n\n\n\n\n\n\nSenthil Todadri (MIT) \nTitle: Strange metals as ersatz Fermi liquids: emergent symmetries\, general constraints\, and experimental tests \nAbstract: The strange metal regime is one of the most prominent features of the cuprate phase diagram but yet has remained amongst the most mysterious. Seemingly similar metallic behavior is seen in a few other metals. In this talk\, I will discuss\, in great generality\, some properties of `strange metals’ in an ideal clean system. I will discuss general constraints[1] on the emergent low energy symmetries of any such strange metal. These constraints may be viewed as a generalization of the Luttinger theorem of ordinary Fermi liquids. Many\, if not all\, non-Fermi liquids will have the same realization of emergent symmetry as a Fermi liquid (even though they could have very different dynamics). Such phases – dubbed ersatz Fermi liquids – share some (but not all) universal properties with Fermi liquids. I will discuss the implications for understanding the strange metal physics observed in experiments . Combined with a few experimental observations\, I will show that these general model-independent considerations lead to concrete predictions[2] about a class of strange metals. The most striking of these is a divergent susceptibility of an observable that has the same symmetries as the loop current order parameter.\n[1]. Dominic Else\, Ryan Thorngren\, T. Senthil\, https://arxiv.org/abs/2007.07896\n[2]. Dominic Else\, T. Senthil\, https://arxiv.org/abs/2010.10523\n\n\n\n\nApril 1\, 2021 |9:00am ET\n\n\n\n\n\n\n\nNaoto Nagaosa (University of Tokyo) \nTitle: Applied physics of high-Tc theories \nAbstract: Since the discovery of high temperature superconductors in cuprates in 1986\, many theoretical ideas have been proposed which have enriched condensed matter theory. Especially\, the resonating valence bond (RVB) state for (doped) spin liquids is one of the most fruitful idea. In this talk\, I would like to describe the development of RVB idea to broader class of materials\, especially more conventional magnets. It is related to the noncollinear spin structures with spin chirality and associated quantal Berry phase applied to many phenomena and spintronics applications. It includes the (quantum) anomalous Hall effect\, spin Hall effect\, topological insulator\, multiferroics\, various topological spin textures\, e.g.\, skyrmions\, and nonlinear optics. I will show that even though the phenomena are extensive\, the basic idea is rather simple and common in all of these topics.\n\n\n\n\nApril 22\, 2021 |10:30am ET\n\n\n\n\n\n\n\nDung-Hai Lee (UC Berkeley) \nTitle: “Non-abelian bosonization in two and three spatial dimensions and some applications” \nAbstract: In this talk\, we generalize Witten’s non-abelian bosonization in $(1+1)$-D to two and three spatial dimensions. Our theory applies to fermions with relativistic dispersion. The bosonized theories are non-linear sigma models with level-1 Wess-Zumino-Witten terms. As applications\, we apply the bosonization results to the $SU(2)$ gauge theory of the $\pi$ flux mean-field theory of half-filled Hubbard model\, critical spin liquids of “bipartite-Mott insulators” in 1\,2\,3 spatial dimensions\, and twisted bilayer graphene.\n\n\n\n\nMay 12\, 2021 |10:30am ET\n\n\n\n\n\n\n\nAndré-Marie Tremblay (Université de Sherbrooke) \nTitle: A unified theoretical perspective on the cuprate phase diagram \nAbstract: Many features of the cuprate phase diagram are a challenge for the usual tools of solid state physics. I will show how a perspective that takes into account both the localized and delocalized aspects of conduction electrons can explain\, at least qualitatively\, many of these features. More specifically\, I will show that the work of several groups using cluster extensions of dynamical mean-field theory sheds light on the pseudogap\, on the quantum-critical point and on d-wave superconductivity. I will argue that the charge transfer gap and oxygen hole content are the best indicators of strong superconductivity and that many observations are a signature of the influence of Mott physics away from half-filling. I will also briefly comment on what information theoretic measures tell us about this problem.\n\n\n\n\nAugust 11\, 2021 |10:30am ET\n\n\n\n\n\n\n\nPiers Coleman (Rutgers) \nTitle: Order Fractionalization* \nAbstract: I will discuss the interplay of spin fractionalization with broken\nsymmetry. When a spin fractionalizes into a fermion\, the resulting particle\ncan hybridize or pair with the mobile electrons to develop a new kind of\nfractional order parameter. The concept of “order fractionalization” enables\nus to extend the concept of off-diagonal order to encompass the formation of\nsuch order parameters with fractional quantum numbers\, such as spinorial\norder[1].\nA beautiful illustration of this phenomenon is provided by a model\nwhich incorporates the Yao-Lee-Kitaev model into a Kondo lattice[2]. This\nmodel explicitly exhibits order fractionalization and is expected to undergo a\ndiscrete Ising phase transition at finite temperature into an\norder-fractionalized phase with gapless Majorana excitations.\nThe broader implications of these considerations for Quantum\nMaterials and Quantum Field Theory will be discussed.\nWork done in collaboration with Yashar Komijani\, Anna Toth and Alexei\nTsvelik.\n[1] Order Fractionalization\, Yashar Komijani\, Anna Toth\, Premala Chandra\, Piers Coleman\, (2018).\n[2] Order Fractionalization in a Kitaev Kondo model\, Alexei Tsvelik and Piers Coleman\, (2021).\n\n\n\n\nSeptember 15\, 2021 |10:30am ET\n\n\n\n\n\n\n\nLiang Fu (MIT) \nTitle: Three-particle mechanism for pairing and superconductivity \nAbstract: I will present a new mechanism and an exact theory of electron pairing due to repulsive interaction in doped insulators. When the kinetic energy is small\, the dynamics of adjacent electrons on the lattice is strongly correlated. By developing a controlled kinetic energy expansion\, I will show that two doped charges can attract and form a bound state\, despite and because of the underlying repulsion. This attraction by repulsion is enabled by the virtual excitation of a third electron in the filled band. This three-particle pairing mechanism leads to a variety of novel phenomena at finite doping\, including spin-triplet superconductivity\, pair density wave\, BCS-BEC crossover and Feshbach resonance involving “trimers”. Possible realizations in moire materials\, ZrNCl and WTe2 will be discussed. \n[1] V. Crepel and L. Fu\, Science Advances 7\, eabh2233 (2021)\n[2] V. Crepel and L. Fu\, arXiv:2103.12060\n[3] K. Slagle and L. Fu\,  Phys. Rev. B 102\, 235423 (2020)\n\n\n\n\nSeptember 29\, 2021 |11:30am ET (special time)\n\n\n\n\n\n\n\nNai Phuan Ong (Princeton University)\n\nTitle:.Abstract: The layered honeycomb magnet alpha-RuCl3 orders below 7 K in a zigzag phase in zero field. An in-plane magnetic field H||a suppresses the zigzag order at 7 Tesla\, leaving a spin-disordered phase widely believed to be a quantum spin liquid (QSL) that extends to ~12 T. We have observed oscillations in the longitudinal thermal conductivity Kxx vs. H from 0.4 to 4 K. The oscillations are periodic in 1/H (with a break-in-slope at 7 T). The amplitude function is maximal in the QSL phase (7 –11.5 T). I will describe a benchmark for crystalline disorder\, the reproducibility and intrinsic nature of the oscillations\, and discuss implications for the QSL state. I will also show detailed data on the thermal Hall conductivity Kxy measured from 0.4 K to 10 K and comment on recent half-quantization results.*Czajka et al.\, Nature Physics 17\, 915 (2021).Collaborators: Czajka\, Gao\, Hirschberger\, Lampen Kelley\, Banerjee\, Yan\, Mandrus and Nagler.\n\n\n\n\nDate TBA |10:30am ET\n\n\n\n\n\n\n\nSuchitra Sebastian (University of Cambridge) \nTitle: TBA\n\n\n\n\nDate TBA |10:30am ET\n\n\n\n\n\n\n\nJenny Hoffman (Harvard University) \nTitle: TBA
URL:https://cmsa.fas.harvard.edu/event/strongly-correlated-quantum-materials-and-high-temperature-superconductors-series/
CATEGORIES:Event,Strongly Correlated Quantum Materials and High-Temperature Superconductors
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