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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211103T140000
DTEND;TZID=America/New_York:20211103T153000
DTSTAMP:20260628T193657
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:20260628T193657
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:20260628T193657
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:20260628T193657
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:20260628T193657
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:20260628T193657
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:20260628T193657
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:20260628T193657
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:20260628T193657
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
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