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DTSTART;TZID=America/New_York:20210915T184600
DTEND;TZID=America/New_York:20210915T194600
DTSTAMP:20260726T165715
CREATED:20240214T092313Z
LAST-MODIFIED:20240301T094948Z
UID:10002623-1631731560-1631735160@cmsa.fas.harvard.edu
SUMMARY:Three-particle mechanism for pairing and superconductivity
DESCRIPTION:Title: 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)
URL:https://cmsa.fas.harvard.edu/event/9-15-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210916T184700
DTEND;TZID=America/New_York:20210916T194700
DTSTAMP:20260726T165715
CREATED:20240214T092053Z
LAST-MODIFIED:20240301T094752Z
UID:10002619-1631818020-1631821620@cmsa.fas.harvard.edu
SUMMARY:The Hilbert Space of large N Chern-Simons matter theories
DESCRIPTION:Title: The Hilbert Space of large N Chern-Simons matter theories \nAbstract: We demonstrate that all known formulae for the thermal partition function for large N Chern Simons matter theory admit a simple Hilbert Space interpretation. In each case this quantity equals the partition function of an associated ungauged large $N$ matter theory with a particular local Lagrangian with one additional element: the Fock Space of this associated theory is projected down to the subspace of its WZW singlets. This projection\, in particular\,  implies the previously encountered `Bosonic Exclusion Principle’\, namely that no single particle state can be occupied by more than $k_B$ particles ($k_B$ is the Chern Simons level). Unlike its Gauss Law counterpart\, the WZW constraint does not trivialize in the large volume limit. However thermodynamics does simplify in this limit;  the final partition function reduces to a product of partition functions associated with each single particle state. These individual single particle state partition functions are a one parameter generalizations of their free boson and free fermion counterparts\, and reduce to the later at extreme values of the ‘t Hooft coupling. At generic values of the rank and the level the occupation statistics of each energy level is given by a $q$ deformation of the usual free formulae of Bose and Fermi statistics.
URL:https://cmsa.fas.harvard.edu/event/9-16-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210917T185400
DTEND;TZID=America/New_York:20210917T195400
DTSTAMP:20260726T165715
CREATED:20240214T091836Z
LAST-MODIFIED:20240301T094616Z
UID:10002617-1631904840-1631908440@cmsa.fas.harvard.edu
SUMMARY:Strong Coupling Theory of Magic-Angle Graphene: A Pedagogical Introduction
DESCRIPTION:Title: Strong Coupling Theory of Magic-Angle Graphene: A Pedagogical Introduction \nAbstract: In this talk\, I will review a recently developed strong coupling theory of magic-angle twisted bilayer graphene. An advantage of this approach is that a single formulation can capture both the insulating and superconducting states\, and with a few simplifying assumptions\, can be treated analytically. I begin by reviewing the electronic structure of magic angle graphene’s flat bands\, in a limit that exposes their peculiar band topology and geometry. I will show how similarities between the flat bands and the lowest Landau level can provide valuable insights into the effect of interactions and form the basis for an analytic treatment of the problem. At integer fillings\, this approach points to flavor ordered insulators\, which can be captured by a sigma-model in its ordered phase. Remarkably\, topological textures of the sigma model carry electric charge which enables the same theory to describe the doped phases away from integer filling. I will show how this approach can lead to superconductivity on disordering the sigma model\, and estimate the Tc for the superconductor. I will highlight the important role played by an effective super-exchange coupling both in pairing and in setting the effective mass of Cooper pairs. At the end\, I will show how this theory provides criteria to predict which multilayer graphene stacks are expected to superconduct including the recently discovered alternating twist trilayer platform.
URL:https://cmsa.fas.harvard.edu/event/9-17-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210922T113300
DTEND;TZID=America/New_York:20210922T133300
DTSTAMP:20260726T165715
CREATED:20240214T091602Z
LAST-MODIFIED:20240301T094449Z
UID:10002615-1632310380-1632317580@cmsa.fas.harvard.edu
SUMMARY:Symmetry types in QFT and the CRT theorem
DESCRIPTION:Title: Symmetry types in QFT and the CRT theorem \nAbstract: I will discuss ideas around symmetry and Wick rotation contained in joint work with Mike Hopkins (https://arxiv.org/abs/1604.06527). This includes general symmetry types for relativistic field theories and their Wick rotation.  I will then indicate how the basic CRT theorem works for general symmetry types\, focusing on the case of the pin groups.  In particular\, I expand on a subtlety first flagged by Greaves-Thomas.
URL:https://cmsa.fas.harvard.edu/event/9-22-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210923T114700
DTEND;TZID=America/New_York:20210923T134700
DTSTAMP:20260726T165715
CREATED:20240214T091227Z
LAST-MODIFIED:20240301T093540Z
UID:10002612-1632397620-1632404820@cmsa.fas.harvard.edu
SUMMARY:Applications of instantons\, sphalerons and instanton-dyons in QCD
DESCRIPTION:Title: Applications of instantons\, sphalerons and instanton-dyons in QCD \nAbstract: I start with a general map of gauge topology\, including monopoles\, instantons and instanton-dyons. Then comes reminder of the “topological landscape”\, the minimal energy gauge field configurations\, as a function of Chern-Simons number Ncs and r.m.s. size. It includes “valleys” at integer Ncs separated by mountain ridges. The meaning of instantons\, instanton-antiinstanton “streamlines” or thimbles\, and sphalerons are reminded\, together with some proposal to produce sphalerons at LHC and RHIC. \nApplications of instanton ensembles\, as a model of QCD vacuum\, are mostly related to their fermionic zero modes  and t’Hooft effective Lagrangian\, which explains explicit and spontaneous breaking of chiral symmetries. Recent applications are related with hadronic wave functions\, at rest and in the light front (LFWFs). Two application would be spin-dependent forces and the so called “flavor asymmetry of antiquark sea” of the nucleons. At temperatures comparable to deconfinement transition\, instantons get split into constituents called instanton-dyons. Studies of their ensemble explains both deconfinement and chiral transitions\, in ordinary and deformed QCD.
URL:https://cmsa.fas.harvard.edu/event/9-23-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210929T114800
DTEND;TZID=America/New_York:20210929T134800
DTSTAMP:20260726T165715
CREATED:20240214T090955Z
LAST-MODIFIED:20240301T093415Z
UID:10002610-1632916080-1632923280@cmsa.fas.harvard.edu
SUMMARY:Oscillations in the thermal conductivity of a spin liquid*
DESCRIPTION:Title: Oscillations in the thermal conductivity of a spin liquid* \nAbstract: 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. \n*Czajka et al.\, Nature Physics 17\, 915 (2021). \nCollaborators: Czajka\, Gao\, Hirschberger\, Lampen Kelley\, Banerjee\, Yan\, Mandrus and Nagler.
URL:https://cmsa.fas.harvard.edu/event/9-29-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211006T114900
DTEND;TZID=America/New_York:20211006T134900
DTSTAMP:20260726T165715
CREATED:20240214T090718Z
LAST-MODIFIED:20240301T093241Z
UID:10002606-1633520940-1633528140@cmsa.fas.harvard.edu
SUMMARY:Line defects in CFTs: Renormalization group flows and semiclassical limits
DESCRIPTION:Title: Line defects in CFTs: Renormalization group flows and semiclassical limits \nAbstract: I will discuss line defects in d-dimensional Conformal Field Theories (CFTs). In the first part of the talk\, I will argue that the ambient CFT places nontrivial constraints on Renormalization Group (RG) flows on such line defects. I will show that the flow on line defects is consequently irreversible and furthermore a canonical decreasing entropy function exists. This construction generalizes the g theorem to line defects in arbitrary dimensions.  In the second part of the talk\, I will present some applications. In particular\, I will discuss impurities with large isospin S for some O(3) symmetric theories in the epsilon expansion.  For sufficiently large S diagrammatic perturbation theory breaks down\, and these are studied in a semiclassical expansion at fixed epsilon S.
URL:https://cmsa.fas.harvard.edu/event/10-6-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T115400
DTEND;TZID=America/New_York:20211007T135400
DTSTAMP:20260726T165715
CREATED:20240214T090253Z
LAST-MODIFIED:20240301T092837Z
UID:10002604-1633607640-1633614840@cmsa.fas.harvard.edu
SUMMARY:A tour of categorical symmetry
DESCRIPTION:Title: A tour of categorical symmetry \nAbstract: I will discuss some perspectives on symmetry coming from the study of topological defects in quantum field theory. I will argue that we should take topological defects themselves to define the symmetries of QFT. This gives us a view of the “category of QFTs”. I will describe some examples of these “categorical symmetries”\, their applications\, and some open problems.
URL:https://cmsa.fas.harvard.edu/event/10-7-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T203000
DTEND;TZID=America/New_York:20211007T220000
DTSTAMP:20260726T165715
CREATED:20240301T093101Z
LAST-MODIFIED:20240301T093101Z
UID:10002891-1633638600-1633644000@cmsa.fas.harvard.edu
SUMMARY:UV/IR and Effective Field Theory
DESCRIPTION:Speaker: Nima Arkani-Hamed (IAS Princeton) \nTitle: UV/IR and Effective Field Theory
URL:https://cmsa.fas.harvard.edu/event/10-7-2021-quantum-matter-in-mathematics-and-physics-2/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211021T153000
DTEND;TZID=America/New_York:20211021T170000
DTSTAMP:20260726T165715
CREATED:20240214T102900Z
LAST-MODIFIED:20240301T091902Z
UID:10002672-1634830200-1634835600@cmsa.fas.harvard.edu
SUMMARY:Electric-magnetic duality and the Geometric Langlands duality
DESCRIPTION:Title: Electric-magnetic duality and the Geometric Langlands duality \nAbstract: I will give a pedagogical review of the connection between electric-magnetic duality and the Geometric Langlands duality.
URL:https://cmsa.fas.harvard.edu/event/10-21-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211029T120000
DTEND;TZID=America/New_York:20211029T130000
DTSTAMP:20260726T165715
CREATED:20240214T102641Z
LAST-MODIFIED:20240301T091452Z
UID:10002670-1635508800-1635512400@cmsa.fas.harvard.edu
SUMMARY:Anomaly resolution via decomposition
DESCRIPTION:Speaker: Eric Sharpe (Virginia Tech) \nTitle: Anomaly resolution via decomposition \nAbstract: In this talk we will discuss a method of anomaly resolution due to Wang-Wen-Witten in the special case of (1+1) dimensional theories. Briefly\, for our purposes\, Wang-Wen-Witten argued that an ill-defined anomalous orbifold [X/G] could be resolved by extending G to a larger group and adding suitable phases.  We analyze this process from the perspective of decomposition\, a property of (1+1)-dimensional theories with “one-form symmetries” first described in 2006.  Examples of such theories include orbifolds with trivially-acting subgroups\, of which the extensions of [X/G] are examples.  After a review of decomposition\, we will see that decomposition implies that in (1+1) dimensions\, the Wang-Wen-Witten procedure results in orbifolds that are equivalent to disjoint unions of orbifolds of X by explicitly nonanomalous subgroups of G.
URL:https://cmsa.fas.harvard.edu/event/10-29-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211029T120000
DTEND;TZID=America/New_York:20211029T130000
DTSTAMP:20260726T165715
CREATED:20240301T091725Z
LAST-MODIFIED:20240301T091725Z
UID:10002890-1635508800-1635512400@cmsa.fas.harvard.edu
SUMMARY:Integrability and chaos of 1+1d chiral edge states
DESCRIPTION:Speaker: Biao Lian (Princeton) \nTitle: Integrability and chaos of 1+1d chiral edge states \nAbstract: I will talk about the integrability and chaos of 1+1d interacting chiral edge states\, which may arise on the edge of 2+1d topological phases. We show that integrable chiral Luttinger liquid is not always a good low energy description of the edge states\, and marginal interactions can significantly affect their spectrum and integrability. We first study N identical chiral Majorana fermion modes with random 4-fermion interactions\, where we show that the system undergoes a transition from integrable to quantum chaotic as N increases. The large N limit defines a chiral SYK model where the Lyapunov exponent in the out-of-time-ordered correlation can be solved analytically. I will also present a chiral SY model consisting of N interacting SU(M)_1 WZW models\, which host anyons and exhibits similar quantum chaos for Abelian anyons. Lastly\, I will talk about the analytical and numerical study of the 4/3 FQH edge theory\, which shows unusual behavior in its integrability.
URL:https://cmsa.fas.harvard.edu/event/10-29-2021-quantum-matter-in-mathematics-and-physics-2/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211103T140000
DTEND;TZID=America/New_York:20211103T153000
DTSTAMP:20260726T165715
CREATED:20240214T102259Z
LAST-MODIFIED:20240301T091205Z
UID:10002667-1635948000-1635953400@cmsa.fas.harvard.edu
SUMMARY:Non-Invertible Duality Defects in 3+1 Dimensions
DESCRIPTION:Speaker: Clay Cordova (U Chicago) \nTitle: Non-Invertible Duality Defects in 3+1 Dimensions \nAbstract:  For any quantum system invariant under gauging a higher-form global symmetry\, we construct a non-invertible topological defect by gauging in only half of spacetime. This generalizes the Kramers-Wannier duality line in 1+1 dimensions to higher spacetime dimensions. We focus on the case of a one-form symmetry in 3+1 dimensions and determine the fusion rule. From modular invariance and a direct analysis of one-form symmetry-protected topological phases\, we show that the existence of certain kinds of duality defects is intrinsically incompatible with a trivially gapped phase. By further assuming time-reversal symmetry\, we find that the presence of certain duality defects implies that the low-energy phase has to be gapless unless the one-form symmetry is spontaneously broken. We give an explicit realization of this duality defect in the free Maxwell theory where the duality defect is realized by a Chern-Simons coupling between the gauge fields from the two sides.
URL:https://cmsa.fas.harvard.edu/event/11-3-3021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211104T103000
DTEND;TZID=America/New_York:20211104T120000
DTSTAMP:20260726T165715
CREATED:20240214T101922Z
LAST-MODIFIED:20240301T091041Z
UID:10002665-1636021800-1636027200@cmsa.fas.harvard.edu
SUMMARY:Fusion Category Symmetries in Quantum Field Theory
DESCRIPTION:Speaker: Yifan Wang (NYU) \nTitle: Fusion Category Symmetries in Quantum Field Theory \nAbstract: Topological defects provide a modern perspective on symmetries in quantum field theory. They generalize the familiar inverti \n \nble symmetries described by groups to non-invertible symmetries described by fusion categories. Such generalized symmetries are ubiquitous in quantum field theory and provide new constraints on renormalization group flows and the IR phase diagram. In this talk I’ll review some recent progress in identifying and understanding fusion category symmetries in 1+1d conformal field theories. Time permitting\, I’ll also comment on higher dimensional generalizations.
URL:https://cmsa.fas.harvard.edu/event/11-4-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211112T143000
DTEND;TZID=America/New_York:20211112T160000
DTSTAMP:20260726T165715
CREATED:20240214T101408Z
LAST-MODIFIED:20240301T090838Z
UID:10002663-1636727400-1636732800@cmsa.fas.harvard.edu
SUMMARY:A degeneracy bound for homogeneous topological order
DESCRIPTION:Speaker: Jeongwan Haah (Microsoft) \nTitle: A degeneracy bound for homogeneous topological order
URL:https://cmsa.fas.harvard.edu/event/11-12-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211116T150000
DTEND;TZID=America/New_York:20211116T163000
DTSTAMP:20260726T165715
CREATED:20240213T064804Z
LAST-MODIFIED:20240213T064804Z
UID:10002130-1637074800-1637080200@cmsa.fas.harvard.edu
SUMMARY:11/16/21 Quantum Matter in Mathematics and Physics
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/11-16-21-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211116T150000
DTEND;TZID=America/New_York:20211116T163000
DTSTAMP:20260726T165715
CREATED:20240214T101038Z
LAST-MODIFIED:20240301T090706Z
UID:10002660-1637074800-1637080200@cmsa.fas.harvard.edu
SUMMARY:Quantum Geometric Aspects of Chiral Twisted Graphene Models
DESCRIPTION:Speaker: Jie Wang (Simons Foundation) \nTitle: Quantum Geometric Aspects of Chiral Twisted Graphene Models \nAbstract: “Moire” materials produced by stacking monolayers with small relative twist angles are of intense current interest for the range of correlated electron phenomena they exhibit. The quench of the kinetic energy means that the interacting physics is controlled by the interplay between the interaction scale and intrinsic quantum geometries of the flat band states\, in particular the Berry curvature and the Fubini-Study metric\, which are in general spatially non-uniform. We show that the analytical solution of the twisted bilayer graphene wavefunction in the chiral limit has a special band geometry\, endowing the Brillouin zone with a complex structure. This talk focus on the origin of the momentum space complex structure\, concrete models that realize it\, and its implications to electron-electron interactions. We first show the momentum space complex structure in Chern number C=1 flatbands implies the Bloch wavefunction to exhibit an exact correspondence to the lowest Landau level in the dual momentum space [2]. We present a generalization of the Haldane pseudopotential concept to deal with interacting problems in these bands and discuss experimental implications [2]. We also present an analytically solvable multi-layer generalized chiral graphene model\, which exhibits arbitrarily high Chern number and ideal quantum geometries [3]. Numerical studies of interacting particles indicate model fractional Chern insulators without Landau level analogues\, characterized by exact degeneracies and infinite particle entanglement spectra gaps [3]. References: \n[1] Jie Wang\, Yunqin Zheng\, Andrew J. Millis\, Jennifer Cano (Phys. Rev. Research 3\, 023155)\n[2] Jie Wang\, Jennifer Cano\, Andrew J. Millis\, Zhao Liu\, Bo Yang (arXiv: 2105.07491\, to appear in PRL)\n[3] Jie Wang\, Zhao Liu (arXiv: 2109.10325)
URL:https://cmsa.fas.harvard.edu/event/11-16-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211118T143000
DTEND;TZID=America/New_York:20211118T160000
DTSTAMP:20260726T165715
CREATED:20240213T064124Z
LAST-MODIFIED:20240213T064401Z
UID:10002122-1637245800-1637251200@cmsa.fas.harvard.edu
SUMMARY:11/18/21 Quantum Matter in Mathematics and Physics
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/11-18-21-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211118T143000
DTEND;TZID=America/New_York:20211118T160000
DTSTAMP:20260726T165715
CREATED:20240214T100731Z
LAST-MODIFIED:20240301T090528Z
UID:10002657-1637245800-1637251200@cmsa.fas.harvard.edu
SUMMARY:Exact Eigenstates in Non-Integrable Systems: A violation of the ETH
DESCRIPTION:Speaker: B. Andrei Bernevig (Princeton University) \nTitle: Exact Eigenstates in Non-Integrable Systems: A violation of the ETH \nAbstract: We find that several non-integrable systems exhibit some exact eigenstates that span the energy spectrum from lowest to the highest state. In the AKLT Hamiltonian and in several others “special” non-integrable models\, we are able to obtain the analytic expression of states exactly and to compute their entanglement spectrum and entropy to show that they violate the eigenstate thermalization hypothesis. This represented the first example of ETH violation in a non-integrable system; these types of states have gained notoriety since then as quantum Scars in the context of Rydberg atoms experiments. We furthermore show that the structure of these states\, in most models where they are found is that of an almost spectrum generating algebra which we call Restricted Spectrum Generating Algebra. This includes the (extended) Hubbard model\, as well as some thin-torus limits of Fractional Quantum Hall states. Yet in other examples\, such as the recently found chiral non-linear Luttinger liquid\, their structure is more complicated and not understood.
URL:https://cmsa.fas.harvard.edu/event/11-18-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Quantum-Matter-in-Mathematics-and-Physics-11.18.21-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211124T103000
DTEND;TZID=America/New_York:20211124T120000
DTSTAMP:20260726T165715
CREATED:20240213T065517Z
LAST-MODIFIED:20240213T065517Z
UID:10002141-1637749800-1637755200@cmsa.fas.harvard.edu
SUMMARY:11/24/21 Quantum Matter in Mathematics and Physics
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/11-24-21-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211124T103000
DTEND;TZID=America/New_York:20211124T120000
DTSTAMP:20260726T165715
CREATED:20240214T100439Z
LAST-MODIFIED:20240301T084626Z
UID:10002655-1637749800-1637755200@cmsa.fas.harvard.edu
SUMMARY:Multipartitioning topological phases and quantum entanglement
DESCRIPTION:Speaker: Shinsei Ryu (Princeton University) \nTitle: Multipartitioning topological phases and quantum entanglement \nAbstract: We discuss multipartitions of the gapped ground states of (2+1)-dimensional topological liquids into three (or more) spatial regions that are adjacent to each other and meet at points. By considering the reduced density matrix obtained by tracing over a subset of the regions\, we compute various correlation measures\, such as entanglement negativity\, reflected entropy\, and associated spectra. We utilize the bulk-boundary correspondence to achieve such multipartitions and construct the reduced density matrix near the entangling boundaries. We find the fingerprints of topological liquid in these quantities\, such as (universal pieces in) the scaling of the entanglement negativity\, and a non-trivial distribution of the spectrum of the partially transposed density matrix.
URL:https://cmsa.fas.harvard.edu/event/11-24-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-11.24.21-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211201T100000
DTEND;TZID=America/New_York:20211201T113000
DTSTAMP:20260726T165715
CREATED:20240213T070149Z
LAST-MODIFIED:20240213T070149Z
UID:10002153-1638352800-1638358200@cmsa.fas.harvard.edu
SUMMARY:12/1/21 Quantum Matter in Mathematics and Physics
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/12-1-21-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211202T103000
DTEND;TZID=America/New_York:20211202T120000
DTSTAMP:20260726T165715
CREATED:20240213T070448Z
LAST-MODIFIED:20240213T070448Z
UID:10002156-1638441000-1638446400@cmsa.fas.harvard.edu
SUMMARY:12/2/21 Quantum Matter in Mathematics and Physics
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/12-2-21-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211202T103000
DTEND;TZID=America/New_York:20211202T120000
DTSTAMP:20260726T165715
CREATED:20240301T083755Z
LAST-MODIFIED:20240301T083839Z
UID:10002887-1638441000-1638446400@cmsa.fas.harvard.edu
SUMMARY:Symmetry in quantum field theory and quantum gravity 2
DESCRIPTION:Speaker: Daniel Harlow (MIT) \nTitle: Symmetry in quantum field theory and quantum gravity 2 \nAbstract: In this talk I will give an overview of semi-recent work with Hirosi Ooguri arguing that three old conjectures about symmetry in quantum gravity are true in the AdS/CFT correspondence.  These conjectures are 1) that there are no global symmetries in quantum gravity\, 2) that dynamical objects transforming in all irreducible representations of any gauge symmetry must exist\, and 3) all internal gauge symmetries must be compact.  Along the way I will need to carefully define what we mean by gauge and global symmetries in quantum field theory and quantum gravity\, which leads to interesting applications in various related fields.  These definitions will be the focus of the first talk\, while the second will apply them to AdS/CFT to prove conjectures 1-3).
URL:https://cmsa.fas.harvard.edu/event/12-2-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-12.02.21-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211208T103000
DTEND;TZID=America/New_York:20211208T120000
DTSTAMP:20260726T165715
CREATED:20240214T094451Z
LAST-MODIFIED:20240301T083428Z
UID:10002644-1638959400-1638964800@cmsa.fas.harvard.edu
SUMMARY:Defects\, link invariants and exact WKB
DESCRIPTION:Speaker: Fei Yan (Rutgers) \nTitle: Defects\, link invariants and exact WKB \nAbstract: I will describe some of my recent work on defects in supersymmetric field theories. The first part of my talk is focused on line defects in certain large classes of 4d N=2 theories and 3d N=2 theories. I will describe geometric methods to compute the ground states spectrum of the bulk-defect system\, as well as implications on the construction of link invariants. In the second part I will talk about some perspectives of surface defects in 4d N=2 theories and related applications on the exact WKB method for ordinary differential equations. This talk is based on past joint work with A. Neitzke\, various work in progress with D. Gaiotto\, S. Jeong\, A. Khan\, G. Moore\, as well as work by myself.
URL:https://cmsa.fas.harvard.edu/event/12-8-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-12.08.21-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211210T143000
DTEND;TZID=America/New_York:20211210T160000
DTSTAMP:20260726T165715
CREATED:20240214T094047Z
LAST-MODIFIED:20240301T083259Z
UID:10002642-1639146600-1639152000@cmsa.fas.harvard.edu
SUMMARY:Gravitational anomaly of 3 + 1 dimensional Z2 toric code with fermionic charges and ferionic loop self-statistics
DESCRIPTION:Speaker: Lukasz Fidkowski (U Washington) \nTitle: Gravitational anomaly of 3 + 1 dimensional Z2 toric code with fermionic charges and ferionic loop self-statistics \nAbstract: Quasiparticle excitations in 3 + 1 dimensions can be either bosons or fermions. In this work\, we introduce the notion of fermionic loop excitations in 3 + 1 dimensional topological phases. Specifically\, we construct a new many-body lattice invariant of gapped Hamiltonians\, the loop self-statistics μ = ±1\, that distinguishes two bosonic topological orders that both superficially resemble 3 + 1d Z2 gauge theory coupled to fermionic charged matter. The first has fermionic charges and bosonic Z2 gauge flux loops (FcBl) and is just the ordinary fermionic toric code. The second has fermionic charges and fermionic loops (FcFl) and\, as we argue\, can only exist at the boundary of a non-trivial 4 + 1d invertible phase\, stable without any symmetries i.e.\, it possesses a gravitational anomaly. We substantiate these claims by constructing an explicit exactly solvable 4 + 1d Walker–Wang model and computing the loop self-statistics in the fermionic Z2 gauge theory hosted at its boundary. We also show that the FcFl phase has the same gravitational anomaly as all-fermion quantum electrodynamics. Our results are in agreement with the recent classification of nondegenerate braided fusion 2- categories\, and with the cobordism prediction of a non-trivial Z2-classified 4+1d invertible phase with action S = (1/2) w2 w3.
URL:https://cmsa.fas.harvard.edu/event/12-10-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220118T143000
DTEND;TZID=America/New_York:20220118T160000
DTSTAMP:20260726T165715
CREATED:20240214T092207Z
LAST-MODIFIED:20240301T075905Z
UID:10002620-1642516200-1642521600@cmsa.fas.harvard.edu
SUMMARY:Metals with strongly correlated electrons: quantum criticality\, disordered interactions\, Planckian dissipation\, and scale invariance
DESCRIPTION:Speaker: Aavishkar Patel (UC Berkeley) \nTitle: Metals with strongly correlated electrons: quantum criticality\, disordered interactions\, Planckian dissipation\, and scale invariance \nAbstract: Metals that do not fit Landau’s famous Fermi liquid paradigm of quasiparticles are plentiful in experiments\, but constructing their theoretical description is a major challenge in modern quantum many-body physics. I will describe new models that can systematically describe such non-Fermi liquid metals at quantum critical points\, and that allow for the accurate computation of a whole host of experimentally measurable static and dynamic quantities despite the presence of both strong correlations and disorder. I will further demonstrate that disorder coupling to interaction operators can lead to the experimentally observed linear-in-temperature (T-linear) resistivity seen at metallic quantum critical points\, and can also generate the observed universal “Planckian” transport scattering rate of kBT/ℏ. Finally\, I will show that “perfect” T-linear resistivity is associated with an energy invariant quantity defined in the many-body microcanonical ensemble\, which motivates the existence of a deep connection between the T-linear resistivity seen at high temperatures and low temperatures with the same slope in many quantum critical materials.
URL:https://cmsa.fas.harvard.edu/event/1-18-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-1.18.22-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220128T143000
DTEND;TZID=America/New_York:20220128T160000
DTSTAMP:20260726T165715
CREATED:20240214T111332Z
LAST-MODIFIED:20240301T074750Z
UID:10002692-1643380200-1643385600@cmsa.fas.harvard.edu
SUMMARY:Maximal quantum chaos of the critical Fermi surface
DESCRIPTION:Speaker: Maria Tikhanovskaya (Harvard) \nTitle: Maximal quantum chaos of the critical Fermi surface \nAbstract: In this talk\, I will describe many-body quantum chaos in a recently proposed large-N theory for critical Fermi surfaces in two spatial dimensions\, by computing out-of-time-order correlation functions. I will use the ladder identity proposed by Gu and Kitaev\, and show that the chaos Lyapunov exponent in this system takes on the maximum possible value of 2πkBT/ℏ\, where T is the absolute temperature. In addition\, by varying the dynamic critical exponent\, I will show that the maximal chaos persists only in the regime where quasiparticles are absent. When quasiparticles are present\, the Lyapunov exponent scales with the temperature as ~ T^a\, where a < 1\, which is parametrically smaller than the maximal rate.
URL:https://cmsa.fas.harvard.edu/event/1-28-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-1.28.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220202T200000
DTEND;TZID=America/New_York:20220202T213000
DTSTAMP:20260726T165715
CREATED:20240214T110015Z
LAST-MODIFIED:20240301T074259Z
UID:10002687-1643832000-1643837400@cmsa.fas.harvard.edu
SUMMARY:Kramers-Wannier-like duality defects in higher dimensions
DESCRIPTION:Title: Kramers-Wannier-like duality defects in higher dimensions \nAbstract: I will introduce a class of non-invertible topological defects in (3 + 1)d gauge theories whose fusion rules are the higher-dimensional analogs of those of the Kramers-Wannier defect in the (1 + 1)d critical Ising model. As in the lower-dimensional case\, the presence of such non-invertible defects implies self-duality under a particular gauging of their discrete (higher-form) symmetries. Examples of theories with such a defect include SO(3) Yang-Mills (YM) at θ = π\, N = 1 SO(3) super YM\, and N = 4 SU(2) super YM at τ = i. I will also explain an analogous construction in (2+1)d\, and give a number of examples in Chern-Simons-matter theories. This talk is based on https://arxiv.org/abs/2111.01141.
URL:https://cmsa.fas.harvard.edu/event/2-2-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-02.02.2022-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220203T113000
DTEND;TZID=America/New_York:20220203T130000
DTSTAMP:20260726T165715
CREATED:20240301T073438Z
LAST-MODIFIED:20240301T073438Z
UID:10002886-1643887800-1643893200@cmsa.fas.harvard.edu
SUMMARY:Quantum Oscillations of Electrical Resistivity in an Insulator
DESCRIPTION:Speaker: Lu 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.
URL:https://cmsa.fas.harvard.edu/event/2-3-2022-quantum-matter-in-mathematics-and-physics-2/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
END:VCALENDAR