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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251008T140000
DTEND;TZID=America/New_York:20251008T150000
DTSTAMP:20260420T072749
CREATED:20250930T181425Z
LAST-MODIFIED:20251009T195959Z
UID:10003801-1759932000-1759935600@cmsa.fas.harvard.edu
SUMMARY:Understanding Optimization in Deep Learning with Central Flows
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Alex Damian\, Harvard \nTitle: Understanding Optimization in Deep Learning with Central Flows \nAbstract: Traditional theories of optimization cannot describe the dynamics of optimization in deep learning\, even in the simple setting of deterministic training. The challenge is that optimizers typically operate in a complex\, oscillatory regime called the “edge of stability.” In this paper\, we develop theory that can describe the dynamics of optimization in this regime. Our key insight is that while the *exact* trajectory of an oscillatory optimizer may be challenging to analyze\, the *time-averaged* (i.e. smoothed) trajectory is often much more tractable. To analyze an optimizer\, we derive a differential equation called a “central flow” that characterizes this time-averaged trajectory. We empirically show that these central flows can predict long-term optimization trajectories for generic neural networks with a high degree of numerical accuracy. By interpreting these central flows\, we are able to understand how gradient descent makes progress even as the loss sometimes goes up; how adaptive optimizers “adapt” to the local loss landscape; and how adaptive optimizers implicitly navigate towards regions where they can take larger steps. Our results suggest that central flows can be a valuable theoretical tool for reasoning about optimization in deep learning. \n 
URL:https://cmsa.fas.harvard.edu/event/newtech_10825/
LOCATION:Hybrid – G10
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-10.8.2025-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250414T150000
DTEND;TZID=America/New_York:20250414T160000
DTSTAMP:20260420T072749
CREATED:20250128T192515Z
LAST-MODIFIED:20250409T174327Z
UID:10003695-1744642800-1744646400@cmsa.fas.harvard.edu
SUMMARY:The Extended Vertex Algebra of 4d N = 2 SCFTs and their Higher Products
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Mitch Weaver\, KAIST \nTitle: The Extended Vertex Algebra of 4d N = 2 SCFTs and their Higher Products \nAbstract: Every 4d N=2 superconformal field theory contains a BPS protected sub-algebra of local operators that has the structure of a vertex operator algebra (VOA). This VOA is identified by passing to the cohomology of a nilpotent supercharge\, T\, whose local operator cohomology is represented by twist-translated Schur operators with support in a Euclidean two-plane. When working in 4d Minkowski space\, this cohomology admits a web of three extended operators (called descent operators) that are constructed from each Schur operator in the VOA\, have worldvolume support in the Lorentzian two-plane that is transverse to the Euclidean plane supporting the VOA\, and behave as point-like insertions in the plane of the VOA\, i.e. as new chiral operators. The combined result is the extended vertex algebra (EVA): a universal extension of the VOA that canonically has the structure of a quasi-VOA\, i.e. a vertex algebra (VA) with no conformal vector but which still possesses a representation of sl(2). After reviewing the VOA of Schur operators\, I will explain the origin of the descent operators and present the OPEs for a subsector of the EVA in the free hyper SCFT.\nTime permitting\, I will also describe the construction and basic properties of a set of higher products that are associated to each descent operator. Such products function as higher dimensional versions of 2d chiral algebra λ-brackets\, i.e. positive mode operators: they are defined on the EVA and map to the operators appearing in the singular terms of OPEs involving descent operators. Their existence offers a route toward sl(2) symmetry enhancement of the EVA and suggests the latter has structural properties that are common to the higher dimensional chiral algebras describing the minimal twists of 3d N = 2 and 4d N = 1 SQFTs. This talk is based on [2211.04410] and forthcoming work.
URL:https://cmsa.fas.harvard.edu/event/qft_41425/
LOCATION:Hybrid – G10
CATEGORIES:Quantum Field Theory and Physical Mathematics
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QFT-and-Physical-Mathematics-4.14.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250312T150000
DTEND;TZID=America/New_York:20250312T170000
DTSTAMP:20260420T072749
CREATED:20250210T183743Z
LAST-MODIFIED:20250307T175626Z
UID:10003711-1741791600-1741798800@cmsa.fas.harvard.edu
SUMMARY:Freedman CMSA Seminar: Michael Freedman (CMSA) & Elia Portnoy (MIT)
DESCRIPTION:Freedman CMSA Seminar \nSpeaker: Michael Freedman\, Harvard CMSA (3:00–4:00 pm ET) \nTitle: How many links can you fit in a box? \nAbstract: I’ll discuss a “made up” problem on the interface of topology and packing\, which may well be classified as “recreational math”.  Here is the first question suppose you have a unit box\, how many unlinked (split) copies of the Hopf link (c_1\,i\,c_2\,i) and be embedded so that for each copy the two components c_1\,i and c_2\,i maintain a distance of at least  some fixed \epsilon >0. Is this number even finite? \n  \nSpeaker: Elia Portnoy\, MIT (4:00–5:00 pm ET) \nTitle: An explicit packing of links in a box and some progress in quantitative embeddings \nAbstract: Following Freedman’s talk\, I’ll begin by showing how to pack a large number of links in a box with certain geometric and topological constraints (joint with Fedya Manin). If time permits\, I’ll also discuss some progress and open questions for the following quantitative embedding problem: given a simplicial complex X\, what is the smallest size of a map from X to R^n so that the preimage of each unit ball intersects a small constant number of simplices? \n 
URL:https://cmsa.fas.harvard.edu/event/freedman_31225/
LOCATION:Hybrid – G10
CATEGORIES:Freedman Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Freedman-Seminar-3.12.25.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250312T140000
DTEND;TZID=America/New_York:20250312T150000
DTSTAMP:20260420T072749
CREATED:20250123T195100Z
LAST-MODIFIED:20250327T194539Z
UID:10003665-1741788000-1741791600@cmsa.fas.harvard.edu
SUMMARY:Discovery in Mathematics with Automated Conjecturing
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Randy Davila\, RelationalAI and Rice University \nTitle: Discovery in Mathematics with Automated Conjecturing \nAbstract: Automated conjecturing is a form of artificial intelligence that applies heuristic-driven methods to mathematical discovery. Since the late 1980s\, systems such as Fajtlowicz’s Graffiti\, DeLaViña’s Graffiti.pc\, and TxGraffiti have collectively contributed to over 130 publications in mathematical journals. In this talk\, we outline the evolution of automated conjecturing\, focusing on TxGraffiti\, a program that employs linear optimization methods and several distinct heuristics to generate mathematically meaningful conjectures. We will then introduce GraphMind\, a dueling framework where the Optimist proposes conjectures while the Pessimist seeks counterexamples\, fostering a feedback loop that strengthens automated reasoning. Finally\, we will present GraffitiAI\, a Python package that extends automated conjecturing across various mathematical domains. \nBio: Randy R. Davila is a Lecturer in the Department of Computational Applied Mathematics & Operations Research at Rice University and a Library Engineer at RelationalAI\, specializing in relational knowledge graph systems for intelligent data management. He earned his PhD in Mathematics from the University of Johannesburg in 2019\, with research focused on graph theory and combinatorial optimization. His work explores artificial intelligence in mathematical conjecture generation\, graph theory\, and neural network applications to combinatorial problems. As the creator of TxGraffiti\, he has developed AI-driven systems that have contributed to numerous mathematical publications. His recent projects include GraphMind\, a dueling agent-based framework that pairs conjecture generation with counterexample discovery\, and GraffitiAI\, a Python package for automated conjecturing across mathematical disciplines. \n 
URL:https://cmsa.fas.harvard.edu/event/newtech_31225/
LOCATION:Hybrid – G10
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-3.12.2025.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240404T130000
DTEND;TZID=America/New_York:20240404T140000
DTSTAMP:20260420T072749
CREATED:20240328T161543Z
LAST-MODIFIED:20240401T210220Z
UID:10003353-1712235600-1712239200@cmsa.fas.harvard.edu
SUMMARY:Shape morphing with swelling hydrogels and expanding foams
DESCRIPTION:Active Matter Seminar \nSpeaker: Abby Plummer\, Boston University \nTitle: Shape morphing with swelling hydrogels and expanding foams \nAbstract: Materials that increase in size offer intriguing possibilities for shape-morphing applications. Here\, we explore two such systems—swelling polyacrylamide hydrogels and expanding polyurethane foams. The hydrogels swell by absorbing water into crosslinked polymer networks. They can therefore be modeled by coupling solvent migration with the deformations of a hyperelastic solid. In contrast\, the foams initially behave as liquids with viscosity and volume increasing in time\, responding elastically only when close to solidification. We investigate how these expanding materials are sculpted by complex environments with obstacles and trenches.
URL:https://cmsa.fas.harvard.edu/event/active-matter-4424/
LOCATION:Hybrid – G10
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-04.04.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231107T110000
DTEND;TZID=America/New_York:20231107T120000
DTSTAMP:20260420T072749
CREATED:20240223T052707Z
LAST-MODIFIED:20240223T052707Z
UID:10002816-1699354800-1699358400@cmsa.fas.harvard.edu
SUMMARY:Fluid stabilization in slowly expanding cosmological spacetime
DESCRIPTION:General Relativity Seminar \nSpeaker: David Fajman (Vienna) \nTitle: Fluid stabilization in slowly expanding cosmological spacetime \nAbstract: Relativistic fluids are known to form shocks during their evolution from near-homogeneous initial data. In expanding spacetimes\, shock formation is suppressed\, if the expansion is sufficiently strong. We refer to this effect as fluid stabilization. The occurrence of this phenomenon depends on features of the fluid and has implications for our understanding of structure formation and cosmological evolution. While the effect is well studied in the regime of accelerated expansion\, in recent years it has been shown that fluid stabilization occurs as well in spacetimes with slower expansion rates. In this talk we present different recent results on fluid stabilization in slowly expanding spacetimes and aspects of the methods involved in the respective proofs. \n  \nTalk via Zoom\, broadcast in G10 \n 
URL:https://cmsa.fas.harvard.edu/event/gr_11723/
LOCATION:Hybrid – G10
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-11.07.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230505T100000
DTEND;TZID=America/New_York:20230505T113000
DTSTAMP:20260420T072749
CREATED:20230802T170945Z
LAST-MODIFIED:20240110T072755Z
UID:10001178-1683280800-1683286200@cmsa.fas.harvard.edu
SUMMARY:Detecting central charge in a superconducting quantum processor
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Sona Najafi (IBM Quantum) \nTitle: Detecting central charge in a superconducting quantum processor \nAbstract: Physical systems at the continuous phase transition point exhibit conformal symmetry rendering local scaling invariance. In two dimensions\, the conformal group possesses infinite generators described by Virasoro algebra with an essential parameter known as a central charge. While the central charge manifests itself in a variety of quantities\, its detection in experimental setup remains elusive. In this work\, we utilize Shannon-Renyi entropy on a local basis of a one-dimensional quantum spin chain at a critical point. We first use a simulated variational quantum eigen solver to prepare the ground state of the critical transfer field Ising model and XXZ model with open and periodic boundary conditions and perform local Pauli X and Z basis measurements. Using error mitigation such as probabilistic error cancellation\, we extract an estimation of the local Pauli observables needed to determine the Shannon-Renyi entropy with respect to subsystem size. Finally\, we obtain the central charge in the sub-leading term of Shannon-Renyi entropy.
URL:https://cmsa.fas.harvard.edu/event/qm_5523/
LOCATION:Hybrid – G10
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-05.05.23-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230421T100000
DTEND;TZID=America/New_York:20230421T113000
DTSTAMP:20260420T072749
CREATED:20230802T170556Z
LAST-MODIFIED:20240131T001826Z
UID:10001176-1682071200-1682076600@cmsa.fas.harvard.edu
SUMMARY:A model of the cuprates: from the pseudogap metal to d-wave superconductivity and charge order
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Prof. Subir Sachdev (Harvard) \nTitle: A model of the cuprates: from the pseudogap metal to d-wave superconductivity and charge order \nAbstract: Soon after the discovery of high-temperature superconductivity in the cuprates\, Anderson proposed a connection to quantum spin liquids. But observations since then have shown that the low-temperature phase diagram is dominated by conventional states\, with a competition between superconductivity and charge-ordered states which break translational symmetry. We employ the “pseudogap metal” phase\, found at intermediate temperatures and low hole doping\, as the parent to the phases found at lower temperatures. The pseudogap metal is described as a fractionalized phase of a single-band model\, with small pocket Fermi surfaces of electron-like quasiparticles whose enclosed area is not equal to the free electron value\, and an underlying pi-flux spin liquid with an emergent SU(2) gauge field. This pi-flux spin liquid is now known to be unstable to confinement at sufficiently low energies. We develop a theory of the different routes to confinement of the pi-flux spin liquid and show that d-wave superconductivity\, antiferromagnetism\, and charge order are natural outcomes. We argue that this theory provides routes to resolving a number of open puzzles on the cuprate phase diagram.\nAs a side result\, at half-filling\, we propose a deconfined quantum critical point between an antiferromagnet and a d-wave superconductor described by a conformal gauge theory of 2 flavors of massless Dirac fermions and 2 flavors of complex scalars coupled as fundamentals to a SU(2) gauge field.\nThis talk is based on Maine Christos\, Zhu-Xi Luo\, Henry Shackleton\, Mathias S. Scheurer\, and S. S.\, arXiv:2302.07885
URL:https://cmsa.fas.harvard.edu/event/qm_42123/
LOCATION:Hybrid – G10
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-04.21.23-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230414T100000
DTEND;TZID=America/New_York:20230414T113000
DTSTAMP:20260420T072749
CREATED:20230802T170408Z
LAST-MODIFIED:20240110T072019Z
UID:10001175-1681466400-1681471800@cmsa.fas.harvard.edu
SUMMARY:Fault-tolerant quantum computation via topological order on fractals and emergent symmetries
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Guanyu Zhu (IBM Quantum\, T. J. Watson Research Center) \nTitle: Fault-tolerant quantum computation via topological order on fractals and emergent symmetries \nAbstract: Topological quantum error correcting codes in integer spatial dimensions have been widely studied in the field of quantum information. A remaining major challenge is to reduce the space-time overhead for universal fault-tolerant quantum computation with topological codes. In the first part of my talk\, I will present a theory of topological order and quantum codes on fractals embedded in three and higher dimensions and its connection to systolic geometry. The construction of such fractal codes can hence significantly reduce the space overhead. In the second part\, I will show how to perform fault-tolerant non-Clifford logical gates in such fractal codes using the idea of emergent symmetries. In particular\, I will discuss the existence of higher-form symmetries corresponding to sweeping of certain codimension-2 invertible defects and exotic gapped boundaries which condense such defects. \nReferences:\n1. PRX Quantum 3 (3)\, 030338 (2022)\, Guanyu Zhu\, Tomas Jochym-O’Connor\, Arpit Dua\n2. arXiv:2201.03568 (2022)\, Arpit Dua\, Tomas Jochym-O'Connor\, Guanyu Zhu\n3. arXiv:2208.07367 (2022)\, Maissam Barkeshli\, Yu-An Chen\, Sheng-Jie Huang\, Ryohei Kobayashi\, Nathanan Tantivasadakarn\, Guanyu Zhu \n 
URL:https://cmsa.fas.harvard.edu/event/qm_4142023/
LOCATION:Hybrid – G10
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-04.14.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230324T100000
DTEND;TZID=America/New_York:20230324T113000
DTSTAMP:20260420T072749
CREATED:20230802T165633Z
LAST-MODIFIED:20240110T055248Z
UID:10001172-1679652000-1679657400@cmsa.fas.harvard.edu
SUMMARY:Traversable wormhole dynamics on a quantum processor
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Alexander Zlokapa\, MIT \nTitle: Traversable wormhole dynamics on a quantum processor \nAbstract: The holographic principle\, theorized to be a property of quantum gravity\, postulates that the description of a volume of space can be encoded on a lower-dimensional boundary. The anti-de Sitter (AdS)/conformal field theory correspondence or duality is the principal example of holography. The Sachdev–Ye–Kitaev (SYK) model of N >> 1 Majorana fermions has features suggesting the existence of a gravitational dual in AdS2\, and is a new realization of holography. We invoke the holographic correspondence of the SYK many-body system and gravity to probe the conjectured ER=EPR relation between entanglement and spacetime geometry through the traversable wormhole mechanism as implemented in the SYK model. A qubit can be used to probe the SYK traversable wormhole dynamics through the corresponding teleportation protocol. This can be realized as a quantum circuit\, equivalent to the gravitational picture in the semiclassical limit of an infinite number of qubits. Here we use learning techniques to construct a sparsified SYK model that we experimentally realize with 164 two-qubit gates on a nine-qubit circuit and observe the corresponding traversable wormhole dynamics. Despite its approximate nature\, the sparsified SYK model preserves key properties of the traversable wormhole physics: perfect size winding\, coupling on either side of the wormhole that is consistent with a negative energy shockwave\, a Shapiro time delay\, causal time-order of signals emerging from the wormhole\, and scrambling and thermalization dynamics. Our experiment was run on the Google Sycamore processor. By interrogating a two-dimensional gravity dual system\, our work represents a step towards a program for studying quantum gravity in the laboratory. Future developments will require improved hardware scalability and performance as well as theoretical developments including higher-dimensional quantum gravity duals and other SYK-like models. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_32423/
LOCATION:Hybrid – G10
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-03.24.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220304T093000
DTEND;TZID=America/New_York:20220304T103000
DTSTAMP:20260420T072749
CREATED:20240214T085309Z
LAST-MODIFIED:20240301T111217Z
UID:10002600-1646386200-1646389800@cmsa.fas.harvard.edu
SUMMARY:Positive Mass\, Density\, and Scalar Curvature on Noncompact Manifolds
DESCRIPTION:Member Seminar \nSpeaker: Martin Lesourd \nTitle: Positive Mass\, Density\, and Scalar Curvature on Noncompact Manifolds \nAbstract: I’ll describe some recent work spanning a couple of different papers on the topics mentioned in the title: Positive Mass\, Density\, and Scalar Curvature on Noncompact Manifolds. Two of these are with R. Unger\, Prof. S-T. Yau\, and two others are with R. Unger\, and Prof. D. A. Lee.
URL:https://cmsa.fas.harvard.edu/event/3-4-2022-member-seminar/
LOCATION:Hybrid – G10
CATEGORIES:Member Seminar
END:VEVENT
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