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DTSTART;TZID=America/New_York:20230303T100000
DTEND;TZID=America/New_York:20230303T113000
DTSTAMP:20260502T093729
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:20230217T100000
DTEND;TZID=America/New_York:20230217T113000
DTSTAMP:20260502T093729
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:20260502T093729
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:20260502T093729
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:20230130T093000
DTEND;TZID=America/New_York:20230130T103000
DTSTAMP:20260502T093729
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:20230124T131500
DTEND;TZID=America/New_York:20230124T144500
DTSTAMP:20260502T093729
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:20260502T093729
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:20260502T093729
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:20221206T090000
DTEND;TZID=America/New_York:20221206T103000
DTSTAMP:20260502T093729
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:20260502T093729
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:20221201T103000
DTEND;TZID=America/New_York:20221201T113000
DTSTAMP:20260502T093729
CREATED:20240301T084120Z
LAST-MODIFIED:20240301T084141Z
UID:10002888-1669890600-1669894200@cmsa.fas.harvard.edu
SUMMARY:Symmetry in quantum field theory and quantum gravity 1
DESCRIPTION:Speaker: Daniel Harlow (MIT) \nTitle: Symmetry in quantum field theory and quantum gravity 1 \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/12-1-2021-quantum-matter-in-mathematics-and-physics/
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-12.01.21-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221122T093000
DTEND;TZID=America/New_York:20221122T110000
DTSTAMP:20260502T093729
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:20221115T093000
DTEND;TZID=America/New_York:20221115T110000
DTSTAMP:20260502T093729
CREATED:20240229T095854Z
LAST-MODIFIED:20240229T095854Z
UID:10002884-1668504600-1668510000@cmsa.fas.harvard.edu
SUMMARY:Topology of the Fermi sea: Ordinary metals as topological materials
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Pok Man Tam (University of Pennsylvania) \nTitle: Topology of the Fermi sea: Ordinary metals as topological materials \nAbstract: It has long been known that the quantum ground state of a metal is characterized by an abstract manifold in momentum space called the Fermi sea. Fermi sea can be distinguished topologically in much the same way that a ball can be distinguished from a donut by counting the number of holes. The associated topological invariant\, i.e. the Euler characteristic (χ_F)\, serves to classify metals. Here I will survey two recent proposals relating χ_F  to experimental observables\, namely: (i) equal-time density/number correlations [1]\, and (ii) Andreev state transport along a planar Josephson junction [2]. Moreover\, from the perspective of quantum information\, I will explain how multipartite entanglement in real space probes the Fermi sea topology in momentum space [1]. Our works not only provide a new connection between topology and entanglement in gapless quantum matters\, but also suggest accessible experimental platforms to extract the topology in metals. \n[1] P. M. Tam\, M. Claassen\, C. L. Kane\, Phys. Rev. X 12\, 031022 (2022) \n[2] P. M. Tam and C. L. Kane\, arXiv:2210.08048 \n 
URL:https://cmsa.fas.harvard.edu/event/qm_tba-7/
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-11.15.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221108T113000
DTEND;TZID=America/New_York:20221108T130000
DTSTAMP:20260502T093729
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:20260502T093729
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:20221025T090000
DTEND;TZID=America/New_York:20221025T103000
DTSTAMP:20260502T093729
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
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221024T090000
DTEND;TZID=America/New_York:20221024T103000
DTSTAMP:20260502T093729
CREATED:20240214T114116Z
LAST-MODIFIED:20240229T111301Z
UID:10002706-1666602000-1666607400@cmsa.fas.harvard.edu
SUMMARY:Insulating BECs and other surprises in dipole-conserving systems
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Ethan Lake (MIT) \nTitle: Insulating BECs and other surprises in dipole-conserving systems \nAbstract: I will discuss recent work on bosonic models whose dynamics conserves both total charge and total dipole moment\, a situation which can be engineered in strongly tilted optical lattices. Related models have received significant attention recently for their interesting out-of-equilibrium dynamics\, but analytic and numeric studies reveal that they also possess rather unusual ground states. I will focus in particular on a dipole-conserving variant of the Bose-Hubbard model\, which realizes an unusual phase of matter that possesses a Bose-Einstein condensate\, but which is nevertheless insulating\, and has zero superfluid weight. Time permitting\, I will also describe the physics of a regime in which these models spontaneously fracture into an exotic type of glassy state. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_102422/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Quantum-Matter-in-Mathematics-and-Physics-10.24.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221018T090000
DTEND;TZID=America/New_York:20221018T103000
DTSTAMP:20260502T093729
CREATED:20240215T104318Z
LAST-MODIFIED:20240229T093815Z
UID:10002744-1666083600-1666089000@cmsa.fas.harvard.edu
SUMMARY:On the six-dimensional origin of non-invertible symmetries
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Michele Del Zotto (Uppsala University) \nTitle: On the six-dimensional origin of non-invertible symmetries \nAbstract: I will present a review about recent progress in charting non-invertible symmetries for four-dimensional quantum field theories that have a six-dimensional origin. These include in particular N=4 supersymmetric Yang-Mills theories\, and also a large class of N=2 supersymmetric theories which are conformal and do not have a conventional Lagrangian description (the so-called theories of “class S”). Among the main results\, I will explain criteria for identifying examples of systems with intrinsic and non-intrinsic non-invertible symmetries\, as well as explore their higher dimensional origin. This seminar is based on joint works with Vladimir Bashmakov\, Azeem Hasan\, and Justin Kaidi. \n 
URL:https://cmsa.fas.harvard.edu/event/qm_101822/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-10.18.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221017T090000
DTEND;TZID=America/New_York:20221017T103000
DTSTAMP:20260502T093729
CREATED:20240215T104548Z
LAST-MODIFIED:20240229T101247Z
UID:10002745-1665997200-1666002600@cmsa.fas.harvard.edu
SUMMARY:Topological Wick Rotation and Holographic duality
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Liang Kong (Sustech) \nTitle: Topological Wick Rotation and Holographic duality \nAbstract: I will explain a new type of holographic dualities between\nn+1D topological orders with a chosen boundary condition and nD\n(potentially gapless) quantum liquids. It is based on the idea of\ntopological Wick rotation\, a notion which was first used in\narXiv:1705.01087 and was named\, emphasized and generalized later in\narXiv:1905.04924. Examples of these holographic dualities include the\nduality between 2+1D toric code model and 1+1D Ising chain and its\nfinite-group generalizations (independently discovered by many\nothers); those between 2+1D topological orders and 1+1D rational\nconformal field theories; and those between n+1D finite gauge theories\nwith a gapped boundary and nD gapped quantum liquids. I will also\nbriefly discuss some generalizations of this holographic duality and\nits relation to AdS/CFT duality.
URL:https://cmsa.fas.harvard.edu/event/qm_101722/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-10.17.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221004T093000
DTEND;TZID=America/New_York:20221004T110000
DTSTAMP:20260502T093729
CREATED:20240216T090303Z
LAST-MODIFIED:20240813T162619Z
UID:10002752-1664875800-1664881200@cmsa.fas.harvard.edu
SUMMARY:Holomorphic Twists and Confinement in N=1 SYM
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Justin Kulp (Perimeter Institute) \nTitle: Holomorphic Twists and Confinement in N=1 SYM \nAbstract: Supersymmetric QFT’s are of long-standing interest for their high degree of solvability\, phenomenological implications\, and rich connections to mathematics. In my talk\, I will describe how the holomorphic twist isolates the protected quantities which give SUSY QFTs their potency by restricting to the cohomology of one supercharge. I will briefly introduce infinite dimensional symmetry algebras\, generalizing Virasoro and Kac-Moody symmetries\, which emerge. Finally\, I will explain a potential novel UV manifestation of confinement\, dubbed “holomorphic confinement\,” in the example of pure SU(N) super Yang-Mills. Based on arXiv:2207.14321 and 2 forthcoming works with Kasia Budzik\, Davide Gaiotto\, Brian Williams\, Jingxiang Wu\, and Matthew Yu.
URL:https://cmsa.fas.harvard.edu/event/qm_tba/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-10.04.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220926T090000
DTEND;TZID=America/New_York:20220926T103000
DTSTAMP:20260502T093729
CREATED:20240216T113233Z
LAST-MODIFIED:20240229T110730Z
UID:10002766-1664182800-1664188200@cmsa.fas.harvard.edu
SUMMARY:Candidates for Non-Supersymmetric Dualities
DESCRIPTION:Quantum Matter in Mathematics and Physics \nSpeaker: Avner Karasik (University of Cambridge\, UK)\nTitle: Candidates for Non-Supersymmetric Dualities \nAbstract: In the talk I will discuss the possibility and the obstructions of finding non-supersymmetric dualities for 4d gauge theories. I will review consistency conditions based on Weingarten inequalities\, anomalies and large N\, and clarify some subtle points and misconceptions about them. Later I will go over some old and new examples of candidates for non-supersymmetric dualities. The will be based on 2208.07842 \n 
URL:https://cmsa.fas.harvard.edu/event/non-invertible-symmetries-in-nature-2/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-09.26.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220913T093000
DTEND;TZID=America/New_York:20220913T110000
DTSTAMP:20260502T093729
CREATED:20240216T114850Z
LAST-MODIFIED:20240229T105748Z
UID:10002768-1663061400-1663066800@cmsa.fas.harvard.edu
SUMMARY:Non-invertible Symmetries in Nature
DESCRIPTION:Quantum Matter in Mathematics and Physics \n\nSpeaker: Yichul Cho (SUNY Stony Brook)\nTitle: Non-invertible Symmetries in Nature \nAbstract: In this talk\, I will discuss non-invertible symmetries in\nfamiliar 3+1d quantum field theories describing our Nature. In\nmassless QED\, the classical U(1) axial symmetry is not completely\nbroken by the ABJ anomaly. Instead\, it turns into a discrete\,\nnon-invertible symmetry. The non-invertible symmetry operator is\nobtained by dressing the naïve U(1) axial symmetry operator with a\nfractional quantum Hall state. We also find a similar non-invertible\nsymmetry in the massless limit of QCD\, which provides an alternative\nexplanation for the neutral pion decay. In the latter part of the\ntalk\, I will discuss non-invertible time-reversal symmetries in 3+1d\ngauge theories. In particular\, I will show that in free Maxwell\ntheory\, there exists a non-invertible time-reversal symmetry at every\nrational value of the theta angle. \nBased on https://arxiv.org/abs/2205.05086 and https://arxiv.org/abs/2208.04331. \n 
URL:https://cmsa.fas.harvard.edu/event/non-invertible-symmetries-in-nature/
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-09.13.22-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220907T090000
DTEND;TZID=America/New_York:20220907T103000
DTSTAMP:20260502T093729
CREATED:20240216T115218Z
LAST-MODIFIED:20240229T105716Z
UID:10002769-1662541200-1662546600@cmsa.fas.harvard.edu
SUMMARY:Gifts from anomalies: new results on quantum critical transport in non- Fermi liquids
DESCRIPTION:Quantum Matter in Mathematics and Physics Seminar \nSpeaker: Zhengyan Darius Shi (MIT)\n\n\nTitle: Gifts from anomalies: new results on quantum critical transport in non-Fermi liquids\nAbstract: Non-Fermi liquid phenomena arise naturally near Landau ordering transitions in metallic systems. Here\, we leverage quantum anomalies as a powerful nonperturbative tool to calculate optical transport in these models in the infrared limit. While the simplest such models with a single boson flavor (N=1) have zero incoherent conductivity\, a recently proposed large N deformation involving flavor-random Yukawa couplings between N flavors of bosons and fermions admits a nontrivial incoherent conductivity  (z is the boson dynamical exponent) when the order parameter is odd under inversion. The presence of incoherent conductivity in the random flavor model is a consequence of its unusual anomaly structure. From this we conclude that the large N deformation does not share important nonperturbative features with the physical N = 1 model\, though it remains an interesting theory in its own right. Going beyond the IR fixed point\, we also consider the effects of irrelevant operators and show\, within the scope of the RPA expansion\, that the old result   due to Kim et al. is incorrect for inversion-odd order parameters.
URL:https://cmsa.fas.harvard.edu/event/gifts-from-anomalies-new-results-on-quantum-critical-transport-in-non-fermi-liquids/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-09.07.22-1-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220816T100000
DTEND;TZID=America/New_York:20220816T113000
DTSTAMP:20260502T093729
CREATED:20240215T100758Z
LAST-MODIFIED:20240229T092227Z
UID:10002738-1660644000-1660649400@cmsa.fas.harvard.edu
SUMMARY:Transport in large-N critical Fermi surface
DESCRIPTION:Speaker: Haoyu Guo (Harvard) \nTitle: Transport in large-N critical Fermi surface\n\nAbstract: A Fermi surface coupled to a scalar field can be described in a 1/N expansion by choosing the fermion-scalar Yukawa coupling to be random in the N-dimensional flavor space\, but invariant under translations. We compute the conductivity of such a theory in two spatial dimensions for a critical scalar. We find a Drude contribution\, and show that a previously proposed \omega^{-2/3} contribution to the optical conductivity at frequency \omega has vanishing co-efficient. We also describe the influence of impurity scattering of the fermions\, and find that while the self energy resembles a marginal Fermi liquid\, the resistivity behaves like a Fermi liquid. Arxiv references: 2203.04990\, 2207.08841
URL:https://cmsa.fas.harvard.edu/event/qm_81622/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220707T103000
DTEND;TZID=America/New_York:20220707T123000
DTSTAMP:20260502T093729
CREATED:20240215T100432Z
LAST-MODIFIED:20240229T091815Z
UID:10002737-1657189800-1657197000@cmsa.fas.harvard.edu
SUMMARY:Anomalies\, dynamics and phases in strongly-coupled chiral gauge theories: Recent developments
DESCRIPTION:Speaker: Kenichi Konishi (UNIPI.IT) \nTitle: Anomalies\, dynamics and phases in strongly-coupled chiral gauge theories: Recent developments \nAbstract: After many years of efforts\, still very little is known today about the physics of strongly-coupled chiral gauge theories in four dimensions\, in spite of an important role they might play in the physics of fundamental interactions beyond the standard SU(3)xSU(2)xU(1) model. This is in stark contrast with the vectorlike gauge theories for which we have many solid results\, thanks to some exact theorems\, to the lattice simulation studies\, to the Seiberg-Witten exact solution of N=2 supersymmetric gauge theories\, and last\, but not the least\, to the real-world strong-interaction phenomenology and experimental tests of Quantum Chromodynamics. \nThe purpose of this seminar is to discuss the results of our recent efforts to improve the understanding of the strongly-coupled chiral gauge theories. Among the main tools of analysis are the consideration of anomalies. We use both the conventional ’t Hooft anomaly-matching ideas\, and new\, more stringent constraints coming from the generalized anomalies involving some higher-form symmetries. Also\, the so-called strong anomalies\, little considered in the context of chiral gage theories\, are found to carry significant implications. \nAs the playground we study several classes of SU(N) gauge theories\, the so-called Bars-Yankielowicz models\, the generalized Georgi-Glashow models\, as well as a few other simple theories with the fermions in complex\, anomaly-free representations of the color SU(N). \nColor-flavor-locked dynamical Higgs phase and dynamical Abelianization\, emerge\, among others\, as two particularly interesting possible phases the system can flow into in the infrared\, depending on the matter fermion content of the model.
URL:https://cmsa.fas.harvard.edu/event/qm_7722/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220525T103000
DTEND;TZID=America/New_York:20220525T120000
DTSTAMP:20260502T093729
CREATED:20240215T101805Z
LAST-MODIFIED:20240215T102153Z
UID:10002740-1653474600-1653480000@cmsa.fas.harvard.edu
SUMMARY:Oblique Lessons from the W Mass Measurement at CDF II
DESCRIPTION:Speaker: Seth Koren (University of Chicago) \nTitle: Baryon Minus Lepton Number BF Theory for the Cosmological Lithium Problem \nAbstract: The cosmological lithium problem—that the observed primordial abundance is lower than theoretical expectations by order one—is perhaps the most statistically significant anomaly of SM+ ΛCDM\, and has resisted decades of attempts by cosmologists\, nuclear physicists\, and astronomers alike to root out systematics. We upgrade a discrete subgroup of the anomaly-free global symmetry of the SM to an infrared gauge symmetry\, and UV complete this at a scale Λ as the familiar U(1)_{B-N_cL} Abelian Higgs theory. The early universe phase transition forms cosmic strings which are charged under the emergent higher-form symmetry of the baryon minus lepton BF theory. These topological defects catalyze interactions which turn N_g baryons into N_g leptons at strong scale rates in an analogue of the Callan-Rubakov effect\, where N_g=3 is the number of SM generations. We write down a model in which baryon minus lepton strings superconduct bosonic global baryon plus lepton number currents and catalyze solely 3p^+ → 3e^+. We suggest that such cosmic strings have disintegrated O(1) of the lithium nuclei formed during Big Bang Nucleosynthesis and estimate the rate\, with our benchmark model finding Λ ~ 10^8 GeV gives the right number density of strings.
URL:https://cmsa.fas.harvard.edu/event/qm_51222/
LOCATION:Hybrid
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.25.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220518T160000
DTEND;TZID=America/New_York:20220518T173000
DTSTAMP:20260502T093729
CREATED:20240215T101105Z
LAST-MODIFIED:20240813T162341Z
UID:10002739-1652889600-1652895000@cmsa.fas.harvard.edu
SUMMARY:Boundary conditions and LSM anomalies of conformal field theories in 1+1 dimensions
DESCRIPTION:Speaker: Linhao Li (ISSP\, U Tokyo) \nTitle: Boundary conditions and LSM anomalies of conformal field theories in 1+1 dimensions \nAbstract: In this talk\, we will study a relationship between conformally invariant boundary conditions and anomalies of conformal field theories (CFTs) in 1+1 dimensions. For a given CFT with a global symmetry\, we consider symmetric gapping potentials which are relevant perturbations to the CFT. If a gapping potential is introduced only in a subregion of the system\, it provides a certain boundary condition to the CFT. From this equivalence\, if there exists a Cardy boundary state which is invariant under a symmetry\, then the CFT can be gapped with a unique ground state by adding the corresponding gapping potential. This means that the symmetry of the CFT is anomaly free. Using this approach\, we will systematically deduce the anomaly-free conditions for various types of CFTs with several different symmetries. When the symmetry of the CFT is anomalous\, it implies a Lieb-Schultz-Mattis type ingappability of the system. Our results are consistent with\, where available\, known results in the literature. Moreover\, we extend the discussion to other symmetries including spin groups and generalized time-reversal symmetries. As an application\, we propose 1d LSM theorem involving magnetic space group symmetries on the lattice. The extended LSM theorems apply to systems with a broader class of spin interactions\, such as Dzyaloshinskii-Moriya interactions and chiral three-spin interactions.
URL:https://cmsa.fas.harvard.edu/event/5-18-2022-quantum-matter-in-mathematics-and-physics-2/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.18.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220518T160000
DTEND;TZID=America/New_York:20220518T173000
DTSTAMP:20260502T093729
CREATED:20240214T095418Z
LAST-MODIFIED:20240813T163304Z
UID:10002651-1652889600-1652895000@cmsa.fas.harvard.edu
SUMMARY:The Generalized Landau Paradigm (a review of generalized symmetries in condensed matter)
DESCRIPTION:Abstract: Recent advances in our understanding of symmetry in quantum many-body systems offer the possibility of a generalized Landau paradigm that encompasses all equilibrium phases of matter. This talk will be an elementary review of some of these developments\, based on: https://arxiv.org/abs/2204.03045
URL:https://cmsa.fas.harvard.edu/event/5-18-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.18.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220512T103000
DTEND;TZID=America/New_York:20220512T120000
DTSTAMP:20260502T093729
CREATED:20240214T100601Z
LAST-MODIFIED:20240813T163153Z
UID:10002656-1652351400-1652356800@cmsa.fas.harvard.edu
SUMMARY:Oblique Lessons from the W Mass Measurement at CDF II
DESCRIPTION:Abstract: The CDF collaboration recently reported a new precise measurement of the W boson mass MW with a central value significantly larger than the SM prediction. We explore the effects of including this new measurement on a fit of the Standard Model (SM) to electroweak precision data. We characterize the tension of this new measurement with the SM and explore potential beyond the SM phenomena within the electroweak sector in terms of the oblique parameters S\, T and U. We show that the large MW value can be accommodated in the fit by a large\, nonzero value of U\, which is difficult to construct in explicit models. Assuming U = 0\, the electroweak fit strongly prefers large\, positive values of T. Finally\, we study how the preferred values of the oblique parameters may be generated in the context of models affecting the electroweak sector at tree- and loop-level. In particular\, we demonstrate that the preferred values of T and S can be generated with a real SU(2)L triplet scalar\, the humble swino\, which can be heavy enough to evade current collider constraints\, or by (multiple) species of a singlet-doublet fermion pair. We highlight challenges in constructing other simple models\, such as a dark photon\, for explaining a large MW value\, and several directions for further study.
URL:https://cmsa.fas.harvard.edu/event/5-12-2022-quantum-matter-in-mathematics-and-physics/
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.12.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220511T103000
DTEND;TZID=America/New_York:20220511T120000
DTSTAMP:20260502T093729
CREATED:20240214T100851Z
LAST-MODIFIED:20240813T163022Z
UID:10002659-1652265000-1652270400@cmsa.fas.harvard.edu
SUMMARY:Cosmology from the vacuum
DESCRIPTION:Abstract: We are familiar with the idea that quantum gravity in AdS can holographically emerge from complex patterns of entanglement\, but can the physics of big bang cosmology emerge from a quantum many-body system? In this talk I will argue that standard tools of holography can be used to describe fully non-perturbative microscopic models of cosmology in which a period of accelerated expansion may result from the positive potential energy of time-dependent scalar fields evolving towards a region with negative potential. In these models\, the fundamental cosmological constant is negative\, and the universe eventually recollapses in a time-reversal symmetric way. The microscopic description naturally selects a special state for the cosmology. In this framework\, physics in the cosmological spacetime is dual to the vacuum physics in a static planar asymptotically AdS Lorentzian wormhole spacetime\, in the sense that the background spacetimes and observables are related by analytic continuation. The dual spacetime is weakly curved everywhere\, so any cosmological observables can be computed in the dual picture via effective field theory without detailed knowledge of the UV completion or the physics near the big bang. Based on 2203.11220 with S. Antonini\, P. Simidzija\, and M. Van Raamsdonk.
URL:https://cmsa.fas.harvard.edu/event/5-11-2022-quantum-matter-in-mathematics-and-physics/
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.11.22-1583x2048-1.png
END:VEVENT
END:VCALENDAR