BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CMSA - ECPv6.16.3//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-ORIGINAL-URL:https://cmsa.fas.harvard.edu
X-WR-CALDESC:Events for CMSA
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20210314T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20211107T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20220313T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20221106T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20230312T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20231105T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20240310T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20241103T060000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230510T140000
DTEND;TZID=America/New_York:20230510T150000
DTSTAMP:20260621T224608
CREATED:20230809T105349Z
LAST-MODIFIED:20240228T104953Z
UID:10001225-1683727200-1683730800@cmsa.fas.harvard.edu
SUMMARY:Modern Hopfield Networks for Novel Transformer Architectures
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Dmitry Krotov\, IBM Research – Cambridge \nTitle: Modern Hopfield Networks for Novel Transformer Architectures \nAbstract: Modern Hopfield Networks or Dense Associative Memories are recurrent neural networks with fixed point attractor states that are described by an energy function. In contrast to conventional Hopfield Networks\, which were popular in the 1980s\, their modern versions have a very large memory storage capacity\, which makes them appealing tools for many problems in machine learning and cognitive and neurosciences. In this talk\, I will introduce an intuition and a mathematical formulation of this class of models and will give examples of problems in AI that can be tackled using these new ideas. Particularly\, I will introduce an architecture called Energy Transformer\, which replaces the conventional attention mechanism with a recurrent Dense Associative Memory model. I will explain the theoretical principles behind this architectural choice and show promising empirical results on challenging computer vision and graph network tasks.
URL:https://cmsa.fas.harvard.edu/event/nt-51023/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-05.10.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230428T100000
DTEND;TZID=America/New_York:20230428T113000
DTSTAMP:20260621T224608
CREATED:20230802T170750Z
LAST-MODIFIED:20240215T115157Z
UID:10001177-1682676000-1682681400@cmsa.fas.harvard.edu
SUMMARY:Fracton Self-Statistics
DESCRIPTION:Quantum Matter Seminar \nTitle: Fracton Self-Statistics \nSpeaker: Hao Song (ITP-CAS) \nAbstract: Fracton order describes novel quantum phases of matter that host quasiparticles with restricted mobility\, and thus lies beyond the existing paradigm of topological order. In particular\, excitations that cannot move without creating other excitations are called fractons. Here we address a fundamental open question — can the notion of self-exchange statistics be naturally defined for fractons\, given their complete immobility as isolated excitations? Surprisingly\, we demonstrate how fractons can be exchanged\, and show their self-statistics is a key part of the characterization of fracton orders. We derive general constraints satisfied by the fracton self-statistics in a large class of abelian fracton orders. Finally\, we show the existence of semionic or fermionic fracton self-statistics in some twisted variants of the checkerboard model and Haah’s code\, establishing that these models are in distinct quantum phases as compared to their untwisted cousins. \nReferences: H Song\, N Tantivasadakarn\, W Shirley\, M Hermele\, arXiv:2304.00028.
URL:https://cmsa.fas.harvard.edu/event/qm_42823/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-04.28.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230427T103000
DTEND;TZID=America/New_York:20230427T113000
DTSTAMP:20260621T224608
CREATED:20230818T043803Z
LAST-MODIFIED:20240119T052918Z
UID:10001262-1682591400-1682595000@cmsa.fas.harvard.edu
SUMMARY:The localized seed-to-solution method for the Einstein constraints
DESCRIPTION:General Relativity Seminar \nSpeaker: Philippe G. LeFloch\, Sorbonne University and CNRS \nTitle: The localized seed-to-solution method for the Einstein constraints \nAbstract: I will discuss advances on asymptotically Euclidian initial data sets and the variational method introduced by J. Corvino and R. Schoen. This talk is based on joint papers with The-Cang Nguyen (Montpellier) and Bruno Le Floch (Sorbonne Univ. and CNRS). In the vicinity of any given reference data set\, we define a “localized seed-to-solution” map\, which allows us to parametrize the initial data sets satisfying the Einstein constraints (possibly with matter fields). The parametrization is defined over classes of data sets understood modulo the image of the dual linearized constraints. Our main contribution concerns the sharp behavior of solutions at infinity\, which we can arbitrarily localize in asymptotic cones in the sense of A. Carlotto and R. Schoen. Most importantly\, as we prove it\, the solutions enjoy sharp decay estimates at the harmonic and super-harmonic levels. In the course of this analysis\, we discover the notion of ‘asymptotic modulators’\, as we call them\, or “correctors” to the standard ADM invariants.
URL:https://cmsa.fas.harvard.edu/event/gr_42723/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-04.27.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230426T140000
DTEND;TZID=America/New_York:20230426T150000
DTSTAMP:20260621T224608
CREATED:20230809T103350Z
LAST-MODIFIED:20240209T151145Z
UID:10001224-1682517600-1682521200@cmsa.fas.harvard.edu
SUMMARY:Toolformer: Language Models Can Teach Themselves to Use Tools
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Timo Schick\, Meta AI \nTitle: Toolformer: Language Models Can Teach Themselves to Use Tools \nAbstract: Language models exhibit remarkable abilities to solve new tasks from just a few examples or textual instructions\, especially at scale. They also\, paradoxically\, struggle with basic functionality\, such as arithmetic or factual lookup\, where much simpler and smaller models excel. In this talk\, we show how these limitations can be overcome by letting language models teach themselves to use external tools via simple APIs. We discuss Toolformer\, a model trained to independently decide which APIs to call\, when to call them\, what arguments to pass\, and how to best incorporate the results into future token prediction. Through this\, it achieves substantially improved zero-shot performance across a variety of downstream tasks without sacrificing its core language modeling abilities. \n 
URL:https://cmsa.fas.harvard.edu/event/nt-42623/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-04.26.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230403T100000
DTEND;TZID=America/New_York:20230403T110000
DTSTAMP:20260621T224608
CREATED:20230825T085504Z
LAST-MODIFIED:20240228T081746Z
UID:10001303-1680516000-1680519600@cmsa.fas.harvard.edu
SUMMARY:Kähler-Einstein metrics on families of Fano varieties
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Chung-Ming Pan\, Institut de Mathématiques de Toulouse \nTitle: Kähler-Einstein metrics on families of Fano varieties \nAbstract: This talk aims to introduce a pluripotential approach to study uniform a priori estimates of Kähler-Einstein (KE) metrics on families of Fano varieties. I will first recall basic tools in the pluripotential theory and the variational approach to complex Monge-Ampère equations. I will then define a notion of convergence of quasi-plurisubharmonic functions in families of normal varieties and extend several classical properties under this context. Last\, I will explain how these elements help to obtain a purely analytic proof of the openness of existing singular KE metrics and a uniform $L^\infty$ estimate of KE potentials. This is joint work with Antonio Trusiani.
URL:https://cmsa.fas.harvard.edu/event/agst-4323/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-AGST-Seminar-04.03.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230322T153000
DTEND;TZID=America/New_York:20230322T163000
DTSTAMP:20260621T224608
CREATED:20230807T172858Z
LAST-MODIFIED:20240215T105007Z
UID:10001192-1679499000-1679502600@cmsa.fas.harvard.edu
SUMMARY:Some rigorous results on the Lévy spin glass model
DESCRIPTION:Probability Seminar \nSpeaker: Wei-Kuo Chen (Minnesota)\n\nTitle: Some rigorous results on the Lévy spin glass model \nAbstract: The Lévy spin glass model\, proposed by Cizeau-Bouchaud\, is a mean-field model defined on a fully connected graph\, where the spin interactions are formulated through a power-law distribution. This model is well-motivated from the study of the experimental metallic spin glasses. It is also expected to bridge between some mean-field and diluted models. In this talk\, we will discuss some recent progress on the Lévy model including its high temperature behavior and the existence and variational expression for the limiting free energy. Based on a joint work with Heejune Kim and Arnab Sen.
URL:https://cmsa.fas.harvard.edu/event/probability-32223/
LOCATION:Virtual
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Probability-Seminar-03.22.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230316T130000
DTEND;TZID=America/New_York:20230316T140000
DTSTAMP:20260621T224608
CREATED:20230824T181630Z
LAST-MODIFIED:20240215T111640Z
UID:10001504-1678971600-1678975200@cmsa.fas.harvard.edu
SUMMARY:Active chemical reactions in phase-separating systems
DESCRIPTION:Active Matter Seminar \n  \n\n\nSpeaker:  Jonathan Bauermann\, Max Planck Institute for the Physics of Complex Systems \n\n\n\nTitle: Active chemical reactions in phase-separating systems \nAbstract: Motivated by the existence of membrane-less compartments in the chemically active environment of living cells\, I will discuss the dynamics of droplets in the presence of active chemical reactions. Therefore\, I will first introduce the underlying interplay between phase separation and active reactions\, which can alter the droplet dynamics compared to equilibrium systems. A key feature of such systems is the emergence of concentration gradients even at steady states. In the second part of this talk\, I will discuss how these gradients can trigger instabilities in the core of chemically active droplets\, giving rise to a new non-equilibrium steady state of liquid spherical shells. Finally\, I will present experimental and theoretical results discussing the existence and energetic cost of this non-equilibrium steady state in a coacervate system.
URL:https://cmsa.fas.harvard.edu/event/am-31623/
LOCATION:Virtual
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=:
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230310T100000
DTEND;TZID=America/New_York:20230310T110000
DTSTAMP:20260621T224608
CREATED:20230802T165201Z
LAST-MODIFIED:20240110T054801Z
UID:10001170-1678442400-1678446000@cmsa.fas.harvard.edu
SUMMARY:Quantum entropy thermalization
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Yichen Huang (Harvard) \nTitle: Quantum entropy thermalization \nAbstract: In an isolated quantum many-body system undergoing unitary evolution\, the entropy of a subsystem (smaller than half the system size) thermalizes if at long times\, it is to leading order equal to the thermodynamic entropy of the subsystem at the same energy. We prove entropy thermalization for a nearly integrable Sachdev-Ye-Kitaev model initialized in a pure product state. The model is obtained by adding random all-to-all 4-body interactions as a perturbation to a random free-fermion model. In this model\, there is a regime of “thermalization without eigenstate thermalization.” Thus\, the eigenstate thermalization hypothesis is not a necessary condition for thermalization. \nReferences: arXiv:2302.10165\, 2209.09826; Joint work with Aram W. Harrow \n 
URL:https://cmsa.fas.harvard.edu/event/qm_31023/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-03.10.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230309T110000
DTEND;TZID=America/New_York:20230309T120000
DTSTAMP:20260621T224608
CREATED:20230807T171904Z
LAST-MODIFIED:20240215T105139Z
UID:10001191-1678359600-1678363200@cmsa.fas.harvard.edu
SUMMARY:On the free energy of spin glasses with multiple types
DESCRIPTION:Probability Seminar \n\nSpeaker: Jean-Christophe Mourrat (ENS Lyon) \nTitle: On the free energy of spin glasses with multiple types \nAbstract: In the simplest spin-glass model\, due to Sherrington and Kirkpatrick\, the energy function involves interaction terms between all pairs of spins. A bipartite version of this model can be obtained by splitting the spins into two groups\, which we can visualize as forming two layers\, and by keeping only interaction terms that go from one to the other layer. For this and other models that incorporate a finite number of types of spins\, the asymptotic behavior of the free energy remains mysterious (at least from the mathematical point of view). I will present the difficulties arising there\, and some partial progress.
URL:https://cmsa.fas.harvard.edu/event/probability-3923/
LOCATION:Virtual
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Probability-Seminar-03.09.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230303T100000
DTEND;TZID=America/New_York:20230303T113000
DTSTAMP:20260621T224608
CREATED:20230802T164922Z
LAST-MODIFIED:20240819T145549Z
UID:10001169-1677837600-1677843000@cmsa.fas.harvard.edu
SUMMARY:Strongly coupled ultraviolet fixed point and symmetric mass generation in four dimensions with 8 Kähler-Dirac fermions
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Anna Hasenfratz (University of Colorado) \nTitle: Strongly coupled ultraviolet fixed point and symmetric mass generation in four dimensions with 8 Kähler-Dirac fermions\n\nAbstract: 4-dimensional gauge-fermion systems exhibit a quantum phase transition from a confining\, chirally broken phase to a conformal phase as the number of fermions is increased. While the existence of the conformal phase is well established\, very little is known about the nature of the phase transition or the strong coupling phase.\n\nLattice QCD methods can predict the RG $\beta$ function\, but the calculations are often limited by non-physical bulk phase transition that prevent exploring the strong coupling region of the phase diagram. Even the critical flavor number is controversial\, estimates vary between $N_f=8$ and 14 for fundamental fermions.\n\nUsing an improved lattice actions that include heavy Pauli-Villars (PV) type bosons to reduce ultraviolet fluctuations\, I was able to simulate an SU(3) system with 8 fundamental flavors at much stronger renormalized coupling than previously possibly. The numerical results indicate a smooth phase transition from weak coupling to a strongly coupled phase.\nI investigate the critical behavior of the transition using finite size scaling. The result of the scaling analysis is not consistent with a first order phase transition\, but it is well described by   Berezinsky-Kosterlitz-Thouless or BKT scaling. BKT scaling could imply that the 8-flavor system is the opening of the conformal window\, an exciting possibility that warrants further investigations.\n\nThe strongly coupled phase appear to be chirally symmetric but gapped\, suggesting symmetric mass generation (SMG). This could be the consequence of the lattice fermions used in this study. Staggered fermions in the massless limit are known to be anomaly free\, allowing an SMG phase in the continuum limit.\n  \n\n\nReferences:\nPhys.Rev.D 106 (2022) 1\, 014513 • e-Print: 2204.04801\nPhys.Rev.D 104 (2021) 7\, 074509 • e-Print: 2109.02790\nFor anomalies and staggered fermion\, see\nPhys.Rev.D 104 (2021) 9\, 094504 • e-Print: 2101.01026\n\nhttps://www.youtube.com/watch?v=3jtNsFGszjE&list=PL0NRmB0fnLJQAnYwkpt9PN2PBKx4rvdup&index=14
URL:https://cmsa.fas.harvard.edu/event/qm_3323/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-03.03.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230223T093000
DTEND;TZID=America/New_York:20230223T103000
DTSTAMP:20260621T224608
CREATED:20230817T184650Z
LAST-MODIFIED:20240118T093227Z
UID:10001255-1677144600-1677148200@cmsa.fas.harvard.edu
SUMMARY:Formation of trapped surfaces in the Einstein-Yang-Mills system
DESCRIPTION:General Relativity Seminar \nSpeaker: Nikolaos Athanasiou (University of Crete\, Greece) \nTitle: Formation of trapped surfaces in the Einstein-Yang-Mills system \nAbstract: The purpose of this talk is to give an overview of a semi-global existence result and a trapped surface formation results in the context of the Einstein-Yang-Mills system. Adopting a “signature for decay rates” approach first introduced by An\, we develop a novel gauge (and scale) invariant hierarchy of non-linear estimates for the Yang-Mills curvature which\, together with the estimates for the gravitational degrees of freedom\, yield the desired semi-global existence result. Once semi-global existence has been established\, we will explain how the formation of a trapped surface follows from a standard ODE argument. This is joint work with Puskar Mondal and Shing-Tung Yau.
URL:https://cmsa.fas.harvard.edu/event/gr_22323/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-02.23.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230222T153000
DTEND;TZID=America/New_York:20230222T163000
DTSTAMP:20260621T224608
CREATED:20230807T171541Z
LAST-MODIFIED:20240111T065432Z
UID:10001190-1677079800-1677083400@cmsa.fas.harvard.edu
SUMMARY:Thresholds for edge colorings
DESCRIPTION:Probability Seminar \nSpeaker: Vishesh Jain (University of Illinois Chicago)\n\nTitle: Thresholds for edge colorings\n\nAbstract: We show that if each edge of the complete bipartite graph K_{n\,n} is given a random list of C(\log n) colors from [n]\, then with high probability\, there is a proper edge coloring where the color of each edge comes from the corresponding list. We also prove analogous results for Latin squares and Steiner triple systems. This resolves several related conjectures of Johansson\, Luria-Simkin\, Casselgren-Häggkvist\, Simkin\, and Kang-Kelly-Kühn-Methuku-Osthus. I will discuss some of the main ingredients which go into the proof: the Kahn-Kalai conjecture\, absorption\, and the Lovasz Local Lemma distribution. Based on joint work with Huy Tuan Pham.
URL:https://cmsa.fas.harvard.edu/event/probability-22223/
LOCATION:Virtual
CATEGORIES:Probability Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230217T100000
DTEND;TZID=America/New_York:20230217T113000
DTSTAMP:20260621T224608
CREATED:20230802T164725Z
LAST-MODIFIED:20240813T161921Z
UID:10001168-1676628000-1676633400@cmsa.fas.harvard.edu
SUMMARY:Quantum Spin Lakes: NISQ-Era Spin Liquids from Non-Equilibrium Dynamics
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Rahul Sahay (Harvard) \nTitle: Quantum Spin Lakes: NISQ-Era Spin Liquids from Non-Equilibrium Dynamics \nAbstract: While many-body quantum systems can in principle host exotic quantum spin liquid (QSL) states\, realizing them as ground states in experiments can be prohibitively difficult. In this talk\, we show how non-equilibrium dynamics can provide a streamlined route toward creating QSLs. In particular\, we show how a simple Hamiltonian parameter sweep can dynamically project out condensed anyons from a family of initial product states (e.g. dynamically “un-Higgs”)\, yielding a QSL-like state. We christen such states “quantum spin lakes” which\, while not thermodynamically large QSLs\, enable their study in NISQ-era quantum simulators. Indeed\, we show that this mechanism sheds light on recent experimental and numerical observations of the dynamical state preparation of the ruby lattice spin liquid in Rydberg atom arrays. Time permitting\, we will discuss how our theory motivates a tree tensor network-based numerical tool—reliant on our theory—that quantitatively reproduces the experimental data two orders of magnitude faster than conventional brute-force simulation methods. Finally\, we will highlight that even spin liquid states that are unstable in equilibrium—namely\, 2 + 1D U(1) spin liquid states—can be robustly prepared by non-equilibrium dynamics. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_21723/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-02.17.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230210T103000
DTEND;TZID=America/New_York:20230210T113000
DTSTAMP:20260621T224608
CREATED:20230802T164450Z
LAST-MODIFIED:20240216T083704Z
UID:10001167-1676025000-1676028600@cmsa.fas.harvard.edu
SUMMARY:Non-invertible Symmetry Enforced Gaplessness
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Ho Tat Lam (MIT) \nTitle: Non-invertible Symmetry Enforced Gaplessness \nAbstract: Quantum systems in 3+1-dimensions that are invariant under gauging a one-form symmetry enjoy novel non-invertible duality symmetries encoded by topological defects. These symmetries are renormalization group invariants which constrain infrared dynamics. We show that such non-invertible symmetries often forbid a symmetry-preserving vacuum state with a gapped spectrum\, leaving only two possibilities for the infrared dynamics: a gapless state or spontaneous breaking of the non-invertible symmetries. These non-invertible symmetries are realized in lattice gauge theories\, which serve to illustrate our results. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_21023/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-02.10.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230203T103000
DTEND;TZID=America/New_York:20230203T113000
DTSTAMP:20260621T224608
CREATED:20230802T164259Z
LAST-MODIFIED:20240215T100905Z
UID:10001166-1675420200-1675423800@cmsa.fas.harvard.edu
SUMMARY:Fracton orders in hyperbolic space and its excitations with fractal mobility
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Han Yan (Rice U) \nTitle: Fracton orders in hyperbolic space and its excitations with fractal mobility \nAbstract: Unlike ordinary topological quantum phases\, fracton orders are intimately dependent on the underlying lattice geometry. In this work\, we study a generalization of the X-cube model\, on lattices embedded in a stack of hyperbolic planes. We demonstrate that for certain hyperbolic lattice tesselations\, this model hosts a new kind of subdimensional particle\, treeons\, which can only move on a fractal-shaped subset of the lattice. Such an excitation only appears on hyperbolic geometries; on flat spaces\, treeons become either a lineon or a planeon. Additionally\, we find intriguingly that for certain hyperbolic tessellations\, a fracton can be created by a membrane operator (as in the X-cube model) or by a fractal-shaped operator within the hyperbolic plane. Our work shows that there are still plenty of exotic behaviors from fracton order to be explored\, especially when the embedding geometry is curved. \nReference: H. Yan\, K. Slage\, A. H. Nevidomskyy\, arXiv:2211.15829 \n 
URL:https://cmsa.fas.harvard.edu/event/qm_2323/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-02.03.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230202T093000
DTEND;TZID=America/New_York:20230202T103000
DTSTAMP:20260621T224608
CREATED:20230817T182911Z
LAST-MODIFIED:20240118T092235Z
UID:10001252-1675330200-1675333800@cmsa.fas.harvard.edu
SUMMARY:Near extremal de Sitter black holes and JT gravity
DESCRIPTION:General Relativity Seminar \nSpeaker: Chiara Toldo (Harvard) \nTitle: Near extremal de Sitter black holes and JT gravity \nAbstract: In this talk I will explore the thermodynamic response near extremality of charged black holes in four-dimensional Einstein-Maxwell theory with a positive cosmological constant. The latter exhibit three different extremal limits\, dubbed cold\, Nariai and ultracold configurations\, with different near-horizon geometries. For each of these three cases I will analyze small deformations away from extremality\, and construct the effective two-dimensional theory\, obtained by dimensional reduction\, that captures these features. The ultracold case in particular shows an interesting interplay between the entropy variation and charge variation\, realizing a different symmetry breaking with respect to the other two near-extremal limits.
URL:https://cmsa.fas.harvard.edu/event/gr_2223/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-02.03.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230130T093000
DTEND;TZID=America/New_York:20230130T103000
DTSTAMP:20260621T224608
CREATED:20230802T163915Z
LAST-MODIFIED:20240215T101107Z
UID:10001165-1675071000-1675074600@cmsa.fas.harvard.edu
SUMMARY:Group Invariant States as Many-Body Scars
DESCRIPTION:Quantum Matter Seminar \nTitle: Group Invariant States as Many-Body Scars \nSpeaker: Igor R. Klebanov (Princeton University) \nAbstract: Quantum many-body scars have been an active area of research in Condensed Matter Physics for several years. In some many-body systems\, the Hilbert space breaks up into a large ergodic sector and a much smaller scar subspace. It has been suggested [K. Pakrouski et al.\, Phys. Rev. Lett. 125 (2020) 230602] that the two sectors may be distinguished by their transformation properties under a large group whose rank grows with the system size (this group is not a symmetry of the Hamiltonian). The scars are invariant under this group\, while all other states are not. We begin by reviewing some many-body systems where group singlet states have special properties: the matrix quantum mechanics and fermionic tensor models. We continue on to appropriately deformed versions of the SU(2) Hubbard model and show that the scar subsector is invariant under a large group\, which acts on the lattice sites. More generally\, we apply this idea to lattice systems with N sites that contain M Majorana fermions per site. The Hilbert space may be decomposed under the action of the SO(N)xSO(M) group\, and the scars are the SO(N) singlets. For any even M\, there are two families of scars. One of them\, which we call the eta-states\, is symmetric under the group O(N) that includes a reflection. The other\, the zeta-states\, has the SO(N) invariance only. For M=4\, where our construction reduces to a deformed SU(2) Hubbard chain with local interactions\, the former family are the N+1 eta-pairing states\, while the latter are the N+1 states of maximum spin. For M=6\, we exhibit explicit formulae for the scar states and calculate the bipartite entanglement entropy analytically. For large N\, it grows logarithmically with the region size. In general\, the energies of the scars within each family are not equidistant. For M>6 we also find that\, with local Hamiltonians\, the scars typically have certain degeneracies.  The latter part of the talk is based on the recent paper “Majorana Scars as Group Singlets” by Zimo Sun\, Fedor Popov\, Igor Klebanov and Kiryl Pakrouski\, arXiv:2212.11914 \n 
URL:https://cmsa.fas.harvard.edu/event/qm_13023/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-1.30.23-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230126T093000
DTEND;TZID=America/New_York:20230126T103000
DTSTAMP:20260621T224608
CREATED:20230817T182501Z
LAST-MODIFIED:20240215T102816Z
UID:10001251-1674725400-1674729000@cmsa.fas.harvard.edu
SUMMARY:Testing spacetime geometry with images of supermassive compact objects: Current status and the future
DESCRIPTION:General Relativity Seminar \nSpeaker: Prashant Kocherlakota (BHI) \nTitle: Testing spacetime geometry with images of supermassive compact objects: Current status and the future \nAbstract: Astrophysical black holes (BHs) are expected to be described by the Kerr solution of the Einstein equations. Several frameworks have recently been developed to parametrically deform the Kerr metric in significantly different ways\, to enable formulations of tests of the no-hair theorems. Testing the viability status of alternative models – such as non-Kerr BHs from general relativity\, BHs from alternative theories\, wormholes\, and other exotic objects – as descriptors of astrophysical objects has been of longstanding interest. The Event Horizon Telescope (EHT) recently imaged Sagittarius A* (Sgr A*)\, the supermassive compact object at the center of the Galaxy\, making such tests possible. In such tests\, the shadow critical curve (or simply shadow boundary)\, defined on the observer’s image plane\, has gained prominence as the observable of interest. We will discuss how the EHT is able to extract information regarding the shadow of Sgr A* and the status of associated tests of the spacetime geometry in the strong-field regime. Future imaging measurements expect to detect the so-called photon ring\, a strong-gravitational lensing feature that appears in the close vicinity of the critical curve\, which houses higher-order images of the emission source. Time permitting\, we will also discuss how these can be used to set up more stringent tests of the spacetime metric and gravity in the future. \n\n 
URL:https://cmsa.fas.harvard.edu/event/gr_12623/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230124T131500
DTEND;TZID=America/New_York:20230124T144500
DTSTAMP:20260621T224608
CREATED:20230802T163601Z
LAST-MODIFIED:20240110T053406Z
UID:10001164-1674566100-1674571500@cmsa.fas.harvard.edu
SUMMARY:Reflections on Parity Breaking
DESCRIPTION:Quantum Matter Seminar \nSpeakers: Jacob McNamara (Caltech) and Matthew Reece (Harvard) \nTitle: Reflections on Parity Breaking \nAbstract: One approach to the Strong CP Problem (known as Nelson-Barr models) is to assume that parity is a gauge symmetry\, which is spontaneously broken in the world around us. In this talk\, we will describe the formal meaning of parity as a gauge symmetry\, and argue that the domain walls formed from spontaneous parity breaking are exactly stable. This stability can be understood as the result of an unusual sort of conserved charge\, which has features in common with both gauge charges and global charges. We will explain how these charges are compatible with the expected absence of global symmetries in quantum gravity\, as well as their relationship with the Swampland Cobordism Conjecture. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_12423/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-1.24.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221220T090000
DTEND;TZID=America/New_York:20221220T103000
DTSTAMP:20260621T224608
CREATED:20240215T105412Z
LAST-MODIFIED:20240819T150130Z
UID:10002746-1671526800-1671532200@cmsa.fas.harvard.edu
SUMMARY:Phase Fluctuations in Two-Dimensional Superconductors and Pseudogap Phenomenon
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Yang Qi (Fudan) \nTitle: Phase Fluctuations in Two-Dimensional Superconductors and Pseudogap Phenomenon \nAbstract: We study the phase fluctuations in the normal state of a general two-dimensional (2d) superconducting system with s-wave pairing. The effect of phase fluctuations of the pairing fields can be dealt with perturbatively using disorder averaging\, after we treat the local superconducting order parameter as a static disordered background. It is then confirmed that the phase fluctuations above the 2d Berenzinskii-Kosterlitz-Thouless (BKT) transition give birth to the pseudogap phenomenon\, leading to a significant broadening of the single-particle spectral functions. Quantitatively\, the broadening of the spectral weights at the BCS gap is characterized by the ratio of the superconducting coherence length and the spatial correlation length of the superconducting pairing order parameter. Our results are tested on the attractive-U fermion Hubbard model on the square lattice\, using unbiased determinant quantum Monte Carlo method and stochastic analytic continuation. We also apply our method to 2d superconductors with d-wave pairing and observe that the phase fluctuations may lead to Fermi-arc phenomenon above the BKT transition.
URL:https://cmsa.fas.harvard.edu/event/qm_122022/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-12.20.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221212T090000
DTEND;TZID=America/New_York:20221212T103000
DTSTAMP:20260621T224608
CREATED:20240215T095743Z
LAST-MODIFIED:20240819T150302Z
UID:10002733-1670835600-1670841000@cmsa.fas.harvard.edu
SUMMARY:Non-Invertible Symmetries from Holography and Branes
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Federico Bonetti (Oxford) \nTitle: Non-Invertible Symmetries from Holography and Branes \nAbstract:  The notion of global symmetry in quantum field theory (QFT) has witnessed dramatic generalizations in the past few years. One of the most exciting developments has been the identification of 4d QFTs possessing non-invertible symmetries\, i.e. global symmetries whose generators exhibit fusion rules that are not group-like. In this talk\, I will discuss realizations of non-invertible symmetries in string theory and holography. As a concrete case study\, I will consider the Klebanov-Strassler setup for holographic confinement in Type IIB string theory. The global symmetries of the holographic 4d QFT (both invertible and non-invertible) can be accessed by studying the topological couplings of the low-energy effective action of the dual 5d supergravity theory. Moreover\, non-invertible symmetry defects can be realized in terms of D-branes. The D-brane picture captures non-trivial aspects of the fusion of non-invertible symmetry defects\, and of their action on extended operators of the 4d QFT.
URL:https://cmsa.fas.harvard.edu/event/qm_121222/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-12.12.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221208T093000
DTEND;TZID=America/New_York:20221208T103000
DTSTAMP:20260621T224608
CREATED:20230817T182138Z
LAST-MODIFIED:20240228T111217Z
UID:10001250-1670491800-1670495400@cmsa.fas.harvard.edu
SUMMARY:A new proof for the nonlinear stability of slowly-rotating Kerr-de Sitter
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Allen Fang (Princeton) \nTitle: A new proof for the nonlinear stability of slowly-rotating Kerr-de Sitter \nAbstract: The nonlinear stability of the slowly-rotating Kerr-de Sitter family was first proven by Hintz and Vasy in 2016 using microlocal techniques. In my talk\, I will present a novel proof of the nonlinear stability of slowly-rotating Kerr-de Sitter spacetimes that avoids frequency-space techniques outside of a neighborhood of the trapped set. The proof uses vector field techniques to uncover a spectral gap corresponding to exponential decay at the level of the linearized equation. The exponential decay of solutions to the linearized problem is then used in a bootstrap proof to conclude nonlinear stability.
URL:https://cmsa.fas.harvard.edu/event/gr_12822/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-12.08.22-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221206T090000
DTEND;TZID=America/New_York:20221206T103000
DTSTAMP:20260621T224608
CREATED:20240215T094810Z
LAST-MODIFIED:20240819T150002Z
UID:10002729-1670317200-1670322600@cmsa.fas.harvard.edu
SUMMARY:Neutrino Masses from Generalized Symmetry Breaking
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Sungwoo Hong (U Chicago & KAIST) \nTitle: Neutrino Masses from Generalized Symmetry Breaking \nAbstract: We explore generalized global symmetries in theories of physics beyond the Standard Model. Theories of Z′ bosons generically contain ‘non-invertible’ chiral symmetries\, whose presence indicates a natural paradigm to break this symmetry by an exponentially small amount in an ultraviolet completion. For example\, in models of gauged lepton family difference such as the phenomenologically well-motivated U(1)Lμ−Lτ\, there is a non-invertible lepton number symmetry which protects neutrino masses. We embed these theories in gauged non-Abelian horizontal lepton symmetries\, e.g. U(1)Lμ−Lτ⊂SU(3)H\, where the generalized symmetries are broken nonperturbatively by the existence of lepton family magnetic monopoles. In such theories\, either Majorana or Dirac neutrino masses may be generated through quantum gauge theory effects from the charged lepton Yukawas e.g. yν∼yτexp(−Sinst). These theories require no bevy of new fields nor ad hoc additional global symmetries\, but are instead simple\, natural\, and predictive: the discovery of a lepton family Z′ at low energies will reveal the scale at which Lμ−Lτ emerges from a larger gauge symmetry. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_12622/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-12.06.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221205T090000
DTEND;TZID=America/New_York:20221205T103000
DTSTAMP:20260621T224608
CREATED:20240215T100106Z
LAST-MODIFIED:20240819T150452Z
UID:10002734-1670230800-1670236200@cmsa.fas.harvard.edu
SUMMARY:Exact Many-Body Ground States from Decomposition of Ideal Higher Chern Bands: Applications to Chirally Twisted Graphene Multilayers
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Junkai Dong (Harvard University) \nTitle: Exact Many-Body Ground States from Decomposition of Ideal Higher Chern Bands: Applications to Chirally Twisted Graphene Multilayers \nAbstract: Motivated by the higher Chern bands of twisted graphene multilayers\, we consider flat bands with arbitrary Chern number C with ideal quantum geometry. While C>1 bands differ from Landau levels\, we show that these bands host exact fractional Chern insulator (FCI) ground states for short range interactions. We show how to decompose ideal higher Chern bands into separate ideal bands with Chern number 1 that are intertwined through translation and rotation symmetry. The decomposed bands admit an SU(C) action that combines real space and momentum space translations. Remarkably\, they also allow for analytic construction of exact many-body ground states\, such as generalized quantum Hall ferromagnets and FCIs\, including flavor-singlet Halperin states and Laughlin ferromagnets in the limit of short-range interactions. In this limit\, the SU(C) action is promoted to a symmetry on the ground state subspace. While flavor singlet states are translation symmetric\, the flavor ferromagnets correspond to translation broken states and admit charged skyrmion excitations corresponding to a spatially varying density wave pattern. We confirm our analytic predictions with numerical simulations of ideal bands of twisted chiral multilayers of graphene\, and discuss consequences for experimentally accessible systems such as monolayer graphene twisted relative to a Bernal bilayer. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_12522/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-12.5.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221122T093000
DTEND;TZID=America/New_York:20221122T110000
DTSTAMP:20260621T224608
CREATED:20240215T100358Z
LAST-MODIFIED:20240819T145840Z
UID:10002736-1669109400-1669114800@cmsa.fas.harvard.edu
SUMMARY:3D gravity and gravitational entanglement entropy
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Gabriel Wong (Harvard CMSA) \nTitle: 3D gravity and gravitational entanglement entropy \nAbstract: Recent progress in AdS/CFT has provided a good understanding of how the bulk spacetime is encoded in the entanglement structure of the boundary CFT. However\, little is known about how spacetime emerges directly from the bulk quantum theory. We address this question in an effective 3d quantum theory of pure gravity\, which describes the high temperature regime of a holographic CFT.  This theory can be viewed as a $q$-deformation and dimensional uplift of JT gravity. Using this model\, we show that the Bekenstein-Hawking entropy of a two-sided black hole equals the bulk entanglement entropy of gravitational edge modes. These edge modes transform under a quantum group\, which defines the data associated to an extended topological quantum field theory. Our calculation suggests an effective description of bulk microstates in terms of collective\, anyonic degrees of freedom whose entanglement leads to the emergence of the bulk spacetime. Finally\, we give a proposal for obtaining the Ryu Takayanagi formula using the same quantum group edge modes. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_112222/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-11.22.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221110T093000
DTEND;TZID=America/New_York:20221110T103000
DTSTAMP:20260621T224608
CREATED:20230817T181337Z
LAST-MODIFIED:20240118T090553Z
UID:10001248-1668072600-1668076200@cmsa.fas.harvard.edu
SUMMARY:Schwarzschild-like Topological Solitons in Gravity
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Pierre Heidmann (Johns Hopkins) \nTitle: Schwarzschild-like Topological Solitons in Gravity \nAbstract: We present large classes of non-extremal solitons in gravity that are asymptotic to four-dimensional Minkowski spacetime plus extra compact dimensions. They correspond to smooth horizonless geometries induced by topology in spacetime and supported by electromagnetic flux\, which characterize coherent states of quantum gravity. We discuss a new approach to deal with Einstein-Maxwell equations in more than four dimensions\, such that they decompose into a set of Ernst equations. We generate the solitons by applying different techniques associated with the Ernst formalism. We focus on solitons with zero net charge yet supported by flux\, and compare them to Schwarzschild black holes. These are also ultra-compact geometries with very high redshift but differ in many aspects. At the end of the talk\, we discuss the stability properties of the solitons and their gravitational signatures.
URL:https://cmsa.fas.harvard.edu/event/gr_111022/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-11.10.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221108T113000
DTEND;TZID=America/New_York:20221108T130000
DTSTAMP:20260621T224608
CREATED:20240214T113153Z
LAST-MODIFIED:20240229T100241Z
UID:10002699-1667907000-1667912400@cmsa.fas.harvard.edu
SUMMARY:Topological symmetry in field theory
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Daniel S. Freed (U Texas) \nTitle: Topological symmetry in field theory \nAbstract: Recently there has been lots of activity surrounding generalized notions of symmetry in quantum field theory\, including “categorical symmetries\,” “higher symmetries\,” “noninvertible symmetries\,” etc. Inspired by definitions of abstract (finite) groups and algebras and their linear actions\, we introduce a framework for these symmetries in field theory and a calculus of topological defects based on techniques in topological field theory. This is joint work with Constantin Teleman and Greg Moore. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_11822/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-11.08.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221101T090000
DTEND;TZID=America/New_York:20221101T103000
DTSTAMP:20260621T224608
CREATED:20240214T113716Z
LAST-MODIFIED:20240229T100642Z
UID:10002703-1667293200-1667298600@cmsa.fas.harvard.edu
SUMMARY:Kardar-Parisi-Zhang dynamics in integrable quantum magnets
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Francisco Machado  (Berkeley/Harvard) \nTitle: Kardar-Parisi-Zhang dynamics in integrable quantum magnets \nAbstract: Although the equations of motion that govern quantum mechanics are well-known\, understanding the emergent macroscopic behavior that arises from a particular set of microscopic interactions remains remarkably challenging. One particularly important behavior is that of hydrodynamical transport; when a quantum system has a conserved quantity (i.e. total spin)\, the late-time\, coarse-grained dynamics of the conserved charge is expected to follow a simple\, classical hydrodynamical description. However the nature and properties of this hydrodynamical description can depend on many details of the underlying interactions. For example\, the presence of additional dynamical constraints can fundamentally alter the propagation of the conserved quantity and induce slower-than-diffusion propagation. At the same time\, the presence of an extensive number of conserved quantities in the form of integrability\, can imbue the system with stable quasi-particles that propagate ballistically through the system. \nIn this talk\, I will discuss another possibility that arises from the interplay of integrability and symmetry; in integrable one dimensional quantum magnets with complex symmetries\, spin transport is neither ballistic nor diffusive\, but rather superdiffusive. Using a novel method for the simulation of quantum dynamics (termed Density Matrix Truncation)\, I will present a detailed analysis of spin transport in a variety of integrable quantum magnets with various symmetries. Crucially\, our analysis is not restricted to capturing the dynamical exponent of the transport dynamics and enables us to fully characterize its universality class: for all superdiffusive models\, we find that transport falls under the celebrated Kardar-Parisi-Zhang (KPZ) universality class. \nFinally\, I will discuss how modern atomic\, molecular and optical platforms provide an important bridge to connect the microscopic interactions to the resulting hydrodynamical transport dynamics. To this end\, I will present recent experimental results\, where this KPZ universal behavior was observed using atoms confined to an optical lattice. \n[1] Universal Kardar-Parisi-Zhang dynamics in integrable quantum systems\nB Ye†\, FM*\, J Kemp*\, RB Hutson\, NY Yao\n(PRL in press) – arXiv:2205.02853 \n[2] Quantum gas microscopy of Kardar-Parisi-Zhang superdiffusion\nD Wei\, A Rubio-Abadal\, B Ye\, FM\, J Kemp\, K Srakaew\, S Hollerith\, J Rui\, S Gopalakrishnan\, NY Yao\, I Bloch\, J Zeiher\nScience (2022) — arXiv:2107.00038 \n 
URL:https://cmsa.fas.harvard.edu/event/qm_11122/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Quantum-Matter-in-Mathematics-and-Physics-11.01.22_Page_1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221027T103000
DTEND;TZID=America/New_York:20221027T113000
DTSTAMP:20260621T224608
CREATED:20230817T180439Z
LAST-MODIFIED:20240118T090238Z
UID:10001246-1666866600-1666870200@cmsa.fas.harvard.edu
SUMMARY:Gravitational Wave\, Angular Momentum\, and Supertranslation Ambiguity
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Naqing Xie (Fudan University) \nTitle: Gravitational Wave\, Angular Momentum\, and Supertranslation Ambiguity\n\nAbstract: The supertranslation ambiguity of angular momentum is a long-standing and conceptually important issue in general relativity. Recently\, there appeared the first definition of angular momentum at null infinity that is supertranslation invariant. However\, in the compact binary coalescence community\, supertranslation ambiguity is often ignored. We have shown that\, in the linearised theory of gravitational wave\, the new angular momentum coincides with the classical definition at the quadrupole level. This talk is based on a recent joint work with Xiaokai He and Xiaoning Wu.
URL:https://cmsa.fas.harvard.edu/event/gr_102722/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221025T090000
DTEND;TZID=America/New_York:20221025T103000
DTSTAMP:20260621T224608
CREATED:20240215T102846Z
LAST-MODIFIED:20240229T092911Z
UID:10002741-1666688400-1666693800@cmsa.fas.harvard.edu
SUMMARY:Unorientable Quantum Field Theories: From crosscaps to holography
DESCRIPTION:Quantum Matter Seminar \nSpeaker: João Caetano (CERN) \nTitle: Unorientable Quantum Field Theories: From crosscaps to holography \nAbstract: In two dimensions\, one can study quantum field theories on unorientable manifolds by introducing crosscaps. This defines a class of states called crosscap states which share a few similarities with the notion of boundary states. In this talk\, I will show that integrable theories remain integrable in the presence of crosscaps\, and this allows to exactly determine the crosscap state. \n\n\nIn four dimensions\, the analog is to place the quantum field theory on the real projective space\, the simplest unorientable 4-manifold. I will show how to do this in the example of N=4 Supersymmetric Yang-Mills\, discuss its holographic description and present a new solvable setup of AdS/CFT.
URL:https://cmsa.fas.harvard.edu/event/qm_102522/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-10.25.22.png
END:VEVENT
END:VCALENDAR