BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Jeremias Aguilera Damia (Centro Atomico Bariloche) DTSTART:20200504T183000Z DTEND:20200504T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/1 DESCRIPTION:Title: Non-Fermi liquid quantum critical points and IR divergencies\n by Jeremias Aguilera Damia (Centro Atomico Bariloche) as part of Kadanoff seminars\n\n\nAbstract\nThe study of metallic Quantum Critical Points with dynamics falling beyond the Fermi Liquid paradigm is well-motivated by ex perimental observations in Strange Metals. Even from a purely theoretical point of view\, the description of these systems by means of a fully consi stent QFT stands as a challenging task. In this talk\, we describe a part icular Quantum Critical Point displaying Non-Fermi Liquid dynamics\, arisi ng by coupling a Fermi Surface to a gapless boson. We extend the descripti on to finite temperatures by proposing a mechanism to resolve the singular behavior associated to static bosons\, thus leading to a consistent chara cterization of the Quantum Critical Region. We also comment on the phenome nological implications of our results.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Wen Wei Ho (Harvard) DTSTART:20200511T183000Z DTEND:20200511T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/2 DESCRIPTION:Title: Interacting phases of matter protected by multiple time-translatio n symmetries in quasiperiodically-driven systems\nby Wen Wei Ho (Harva rd) as part of Kadanoff seminars\n\n\nAbstract\nThe discrete time-translat ion symmetry of a periodically-driven (Floquet) system allows for the exis tence of novel\, nonequilibrium interacting phases of matter. A well-known example is the discrete time crystal\, a phase characterized by the spont aneous breaking of this time-translation symmetry. In this talk\, I will s how that the presence of *multiple* time-translation symmetries\, realized by quasiperiodically driving a system with two or more incommensurate fre quencies\, leads to a panoply of novel non-equilibrium phases of matter\, both spontaneous symmetry-breaking ("discrete time quasi-crystals") and to pological. I will demonstrate that these phases are stable in a long-lived \, 'preheating' regime\, by outlining rigorous mathematical results establ ishing slow heating at high driving frequencies. As a byproduct\, I will i ntroduce the notion of many-body localization (MBL) in quasiperiodically-d riven systems.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Chong Wang (Perimeter Institute) DTSTART:20200518T183000Z DTEND:20200518T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/3 DESCRIPTION:Title: A theory of deconfined pseudo-criticality\nby Chong Wang (Peri meter Institute) as part of Kadanoff seminars\n\n\nAbstract\nIt has been p roposed that the deconfined criticality in (2+1)d - the quantum phase tran sition between a Neel anti-ferromagnet and a valence-bond-solid (VBS) - ma y actually be pseudo-critical\, in the sense that it is a weakly first-ord er transition with a generically long correlation length. The underlying f ield theory of the transition would be a slightly complex (non-unitary) fi xed point as a result of fixed points annihilation. This proposal was moti vated by existing numerical results from large scale Monte-Carlo simulatio ns as well as conformal bootstrap. However\, an actual theory of such comp lex fixed point\, incorporating key features of the transition such as the emergent SO(5) symmetry\, is so far absent. Here we propose a Wess-Zumino -Witten (WZW) nonlinear sigma model with level k=1\, defined in 2+ϵ dimen sions\, with target space S^(3+ϵ) and global symmetry SO(4+ϵ). This give s a formal interpolation between the deconfined criticality at d=3 and the SU(2)_1 WZW theory at d=2 describing the spin-1/2 Heisenberg chain. The t heory can be formally controlled\, at least to leading order\, in terms of the inverse of the WZW level 1/k. We show that at leading order\, there i s a fixed point annihilation at d*≈2.77\, with complex fixed points abov e this dimension including the physical d=3 case. The pseudo-critical prop erties such as correlation length\, scaling dimensions and the drifts of s caling dimensions as the system size increases\, calculated crudely to lea ding order\, are qualitatively consistent with existing numerics.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Gabriel Cuomo (EPFL) DTSTART:20200601T183000Z DTEND:20200601T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/4 DESCRIPTION:Title: The epsilon expansion meets semiclassics\nby Gabriel Cuomo (EP FL) as part of Kadanoff seminars\n\n\nAbstract\nIn this talk\, I will stud y the scaling dimension of the lightest operator of charge n in the U(1) m odel at the Wilson-Fisher fixed point in 4-ε dimensions.\nEven for a pert urbatively small fixed point coupling λ\, standard perturbation theory br eaks down for sufficiently large λ n. Treating λ n as fixed for small λ \, I will show that the scaling dimension can be successfully computed thr ough a semiclassical expansion around a non-trivial trajectory\, resulting in a series in the coupling whose coefficients are fixed functions of λ n. I will discuss explicitly the computation of the first two orders in th e expansion. The result\, when expanded at small λ n\, perfectly agrees w ith all available diagrammatic computations. The asymptotic at large λ n reproduces the systematic large charge expansion\, recently derived in CFT .\nSimilar results can be derived in the U(1) model in 3-ε dimensions. I will briefly comment on the application of similar ideas in the calculatio n of other observables\, such as three-point functions of charged operator s. This talk is based on https://arxiv.org/abs/1909.01269 and https://arxi v.org/abs/1911.08505.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Ki-Seok Kim (POSTECH) DTSTART:20200608T183000Z DTEND:20200608T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/5 DESCRIPTION:Title: Emergent holographic dual effective field theory as a mean-field t heory with all-loop quantum corrections in the large N limit\nby Ki-Se ok Kim (POSTECH) as part of Kadanoff seminars\n\n\nAbstract\nHolographic d uality conjecture states that a D-dimensional quantum field theory can be duality-mapped into a (D+1)-dimensional quantum gravity theory\, where the quantum gravity theory is a “hologram” of the quantum field theory. A lthough this holographic duality conjecture serves as a novel non-perturba tive theoretical framework for strongly coupled quantum field theories\, t he duality transformation has not been clarified until now. In this study we propose a prescription for the holographic duality transformation based on Wilsonian recursive renormalization group (RG) transformations. As a r esult\, we manifest the RG flow of an effective field theory with the intr oduction of an emergent extra dimensional space\, where RG beta-functions to describe the evolution of coupling functions appear in the resulting ef fective action explicitly through the extra dimensional space. This micros copic construction of the dual holographic mapping suggests that the origi n of non-perturbative physics is in intertwined renormalization between dy namics and geometry.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Michael Aizenman (Princeton) DTSTART:20200615T183000Z DTEND:20200615T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/6 DESCRIPTION:Title: Marginal triviality of the scaling limits of 4D critical Ising and $\\varphi^4_4$ models\nby Michael Aizenman (Princeton) as part of Kad anoff seminars\n\n\nAbstract\nThe talk will outline the recent proof that the scaling limits of spin fluctuations in four-dimensional Ising-type mod els at or near the critical point are Gaussian\, and of the similar statem ent for the $\\varphi^4_4$ fields with a lattice ultraviolet cutoff\, in t he limit of infinite volume and vanishing lattice spacing (derived jointl y with H. Duminil-Copin). The proofs are enabled by the models' random cu rrent representation\, in which the correlation functions' deviation from Wick's law are expressed in terms of intersection probabilities of random currents with prescribed sources. Examples will also be provided of ins ights facilitated by this representation for two and three dimensions.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Sri Raghu (Stanford) DTSTART:20200831T183000Z DTEND:20200831T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/7 DESCRIPTION:Title: Dual perspective on quantum Hall to insulator transitions\nby Sri Raghu (Stanford) as part of Kadanoff seminars\n\n\nAbstract\nQuantum H all to insulator transitions (QHITs) are among the oldest and most studied examples of quantum critical phenomena. In this talk I will discuss prob lems that still remain open in this subject\, and present a dual approach to QHITs based on composite fermion representations. I discuss the mean-f ield and fluctuational aspects of the dual theories\, and discuss how they provide a complementary understanding - and in many instances\, a concep tual advantage - to current descriptions of QHITs based on the electron re presentation.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Shiraz Minwalla (TIFR Mumbai) DTSTART:20200908T150000Z DTEND:20200908T160000Z DTSTAMP:20260404T111216Z UID:Kadanoff/8 DESCRIPTION:Title: Fermi seas from Bose condensates and a bosonic exclusion principle in matter Chern Simons theories\nby Shiraz Minwalla (TIFR Mumbai) as part of Kadanoff seminars\n\n\nAbstract\nI will study Chern Simons gauge t heories in three dimensions coupled to (bosonic or fermionic) matter in th e fundamental representation in the large N limit. I will first explain ho w previously obtained results for the thermal free energy in these theorie s can be generalized to values of the chemical potential that are larger t han quasi particle mases. I will then use these results to find a simple explicit formula for the occupation number for a bosonic quasiparticle sta te of any given energy and charge as a function of the temperature and che mical potential. This formula is a generalization to finite 't Hooft coupl ing of the famous result of Bose-Einstein statistics. It implies the follo wing exclusion principle for large N Chern Simons coupled bosons: the to tal number of bosons occupying any single state cannot exceed the Chern Si mons level. Specializing to zero temperature I will also construct the ph ase diagrams of these theories as a function of chemical potential and th e UV parameters. The phase diagram includes a Bose condensed phase\, dual to the Fermionic Fermi sea. The runaway instability of free theories at la rge chemical potential is cured by the bosonic exclusion principle.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Alex Maloney (McGill) DTSTART:20200914T183000Z DTEND:20200914T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/9 DESCRIPTION:Title: Gravity from Averaging CFTs\nby Alex Maloney (McGill) as part of Kadanoff seminars\n\n\nAbstract\nI will explore the idea that certain t heories of gravity in Anti-de Sitter space are dual to an average over an ensemble of quantum theories\, rather than to a specific quantum theory. I will describe an average over Narain’s family of two-dimensional confo rmal field theories which describe free bosons on a torus\, and compute th e partition function using the Siegel-Weil formula. The result takes the form of a sum over geometries as one would expect in a theory of gravity. But the gravitational theory looks more like a Chern-Simons theory than l ike Einstein gravity.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Hong Liu (MIT) DTSTART:20200921T183000Z DTEND:20200921T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/10 DESCRIPTION:Title: Entanglement entropies of equilibrated pure states in quantum man y-body systems and replica wormholes\nby Hong Liu (MIT) as part of Kad anoff seminars\n\n\nAbstract\nWe develop a universal approximation for the Renyi entropies of a pure state at late times in non-integrable systems\, which macroscopically resembles an equilibrium density matrix. The result ing expressions are fully determined by properties of the associated equil ibrium density matrix\, and are hence independent of the details of the in itial state\, while also being manifestly consistent with unitary time-evo lution. For equilibrated pure states in gravity systems\, such as those in volving black holes\, this approximation gives a prescription for calculat ing entanglement entropies using Euclidean path integrals which is consist ent with unitarity and hence can be used to address the information loss p aradox of Hawking. Applied to recent models of evaporating black holes and eternal black holes coupled to baths\, it provides a derivation of replic a wormholes\, and elucidates their mathematical and physical origins. In p articular\, it shows that replica wormholes can arise in a system with a f ixed Hamiltonian\, without the need for ensemble averages.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Mark Van Raamsdonk (University of British Columbia) DTSTART:20200928T183000Z DTEND:20200928T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/11 DESCRIPTION:Title: Towards Microscopic Models of Big Bang Cosmology\nby Mark Van Raamsdonk (University of British Columbia) as part of Kadanoff seminars\n \n\nAbstract\nIn this talk\, we review an approach to describing cosmologi cal physics using ordinary AdS/CFT\, where the cosmological physics is the effective description of an end-of-the-world brane which cuts off the sec ond asymptotic region of a two-sided black hole. The worldvolume geometry of the brane is an FRW big-bang/big-crunch spacetime. In favorable circums tances\, the brane acts as a Randall-Sundrum Planck brane so that gravity localizes. We describe a microscopic construction for such an end-of-the-w orld brane with localized gravity in AdS/CFT\, starting from N=4 SYM theor y. We suggest specific microscopic states of N=4 SYM theory that may encod e the physics in a four-dimensional cosmological spacetime.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Simon Caron-Huot (McGill) DTSTART:20201005T203000Z DTEND:20201005T213000Z DTSTAMP:20260404T111216Z UID:Kadanoff/12 DESCRIPTION:Title: Dispersion relations for S-matrices and CFTs\nby Simon Caron- Huot (McGill) as part of Kadanoff seminars\n\n\nAbstract\nDispersion relat ions are statements of causality. They give sum rules connecting low and high energies. They are great. I will review some recently derived conse quences of causality and how they relate to dispersion relations. I will t hen discuss a surprising equivalence between three seemingly distinct disp ersion relations in CFTs (in position space\, Mellin space\, and analytic functionals)\, and a lesson for flat-space gravity.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Julian Sonner (University of Geneva) DTSTART:20201012T183000Z DTEND:20201012T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/13 DESCRIPTION:Title: Causal symmetry breaking: late time physics of holographic quantu m chaos\nby Julian Sonner (University of Geneva) as part of Kadanoff s eminars\n\n\nAbstract\nQuantum chaotic systems are often defined via the a ssertion that their spectral statistics coincides with\, or is well approx imated by\, random matrix theory. In this talk I will explain how the univ ersal content of random matrix theory emerges as the consequence of a simp le symmetry-breaking principle and its associated Goldstone modes. Within AdS/CFT this gives a universal framework to express correlations between ` `different universes’’\, including for individual theories rather than ensembles. I will Illustrate the bulk picture of this EFT using the examp le minimal string theory. I will end by discussing the construction of the EFT of quantum chaos also in higher dimensional field theories\, as appli cable for example for higher-dimensional AdS/CFT dual pairs.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Ryan Thorngren (Harvard CMSA) DTSTART:20201019T183000Z DTEND:20201019T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/14 DESCRIPTION:Title: 't Hooft Anomalies of Fermi Liquids and Luttinger's Theorem\n by Ryan Thorngren (Harvard CMSA) as part of Kadanoff seminars\n\n\nAbstrac t\nLattice systems with translation symmetry and U(1) charge conservation have a filling fraction\, defined as the charge per unit cell. In this tal k I will explain how the filling fraction is captured by anomalous emergen t symmetries in the continuum limit of such systems. This anomaly matching is a generalization of Luttinger's theorem for Fermi liquids\, which says that the filling fraction equals the volume enclosed by the Fermi surface . Luttinger's theorem is obtained by analyzing an anomalous loop-group sym metry of the Fermi liquid\, which generalizes the chiral anomaly of a Lutt inger liquid in 1+1d. I will argue more generally that systems at irration al filling cannot have continuum limits with compact symmetry groups.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Ehud Altman (Berkeley) DTSTART:20201109T193000Z DTEND:20201109T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/15 DESCRIPTION:Title: Symmetry and information flow in quantum circuits with measuremen ts\nby Ehud Altman (Berkeley) as part of Kadanoff seminars\n\n\nAbstra ct\nI will discuss novel quantum phases and phase transitions that emerge in the dynamics of quantum circuits and represent distinct modes of inform ation flow. I consider a system in which the time evolution by random unit ary gates is occasionally interrupted by local measurements. It was previo usly found that such evolution leads to a phase transition in the entangle ment of the wavefunction: at steady state it is characterized by volume la w entanglement for small measurement rate\, while it is an area law above a threshold rate. I will investigate this phase transition by mapping the quantum dynamics into classical statistical mechanics models in equilibriu m. Furthermore\, we show that more phases are possible if we impose symmet ries on the dynamics. To identify the phases\, we develop a mapping betwee n the information dynamics in a broad class of circuits to the ground stat es of effective spin Hamiltonians\, which possess a higher symmetry than t he original circuit. The different ground state phases admitted by the hig her effective symmetry correspond to distinct patterns of information flow and scrambling in the circuit dynamics. We illustrate these ideas with tw o examples: (i) a quantum circuit with Z_2 symmetry resulting in non-abeli an D_4 symmetry in an effective Hamiltonian and (ii) a quadratic fermionic circuit leading to U(1) symmetry. The latter exhibits Kosterlitz–Thoule ss transition in 1D between a critical phase with log(L) entanglement and "trivial" area law phases. Our work is a first step toward the classificat ion of information flow in generic quantum circuits.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Israel Klich (University of Virginia) DTSTART:20201026T183000Z DTEND:20201026T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/16 DESCRIPTION:by Israel Klich (University of Virginia) as part of Kadanoff s eminars\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Alexander Seidel (Washington University in St. Louis) DTSTART:20201214T193000Z DTEND:20201214T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/17 DESCRIPTION:Title: Entangled Pauli Principles\nby Alexander Seidel (Washington U niversity in St. Louis) as part of Kadanoff seminars\n\n\nAbstract\nA majo r challenge in the study of strongly correlated electron systems is to est ablish a firm link between microscopic models and effective field theory. Quite often\, this step involves a leap of faith\, and/or extensive numeri cal studies. For fractional quantum Hall model wave functions\, there exis ts — in some cases — a scheme to infer the long distance physics of a state that is both compelling and simple\, and leaves very little room for ambiguity. This scheme involves a local parent Hamiltonian for the state\ , which unambiguously defines a ``zero mode space’’ of elementary exci tations\, and what’s known as a ``generalized Pauli principle’’. Th e latter efficiently organizes the zero mode space through one-dimensional patterns satisfying local rules and effectively functions as the ``DNA’ ’ of the topological phase:\nWhere this works\, universal properties of the state emerge from counting exercises in terms of these patterns\, whic h efficiently and unambiguously encode the edge conformal field theory and related topological data. This includes a natural scheme to infer braidin g statistics directly\, for both Abelian and non-Abelian states. The stron g link between microscopics and effective theory brought about by the exis tence of a particular type of parent Hamiltonian\, one which enforces a Pa uli-like in its zero modes\, is thus far limited to a subset of the myriad phases possible in the fractional quantum Hall regime. I will report on r ecent progress on extending this paradigm into new terrain where it previo usly did not\, or did not fully apply\, including most composite fermion s tates and their ``parton’’ generalizations\, leading to ``entangled’ ’ Pauli-like principles. I will argue that these examples suggest the b eginnings of a new ``Hamiltonian building’’ framework that capitalizes on the matrix product form of fractional quantum Hall trial states\, rath er than their analytic first quantized form.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Tomaž Prosen (University of Ljubljana) DTSTART:20201102T193000Z DTEND:20201102T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/18 DESCRIPTION:Title: Exactly solved models of many-body quantum chaos\nby Tomaž P rosen (University of Ljubljana) as part of Kadanoff seminars\n\n\nAbstract \nOne should be amazed with the unreasonable effectiveness of random matri x theory to describe spectral fluctuations in simple non-integrable many-b ody systems\, say one dimensional spin 1/2 chains with local interactions. I will discuss several models of Floquet (periodically driven) quantum sp in chains\, where the random matrix result for the spectral form factor ca n be derived or even rigorously proven. Several other nontrivial exactly s olvable features of the presented models\, such as dynamical correlations or entanglement dynamics\, will be discussed.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Leo Radzihovsky (University of Colorado Boulder) DTSTART:20201207T193000Z DTEND:20201207T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/19 DESCRIPTION:Title: Quantum smectic gauge theory\nby Leo Radzihovsky (University of Colorado Boulder) as part of Kadanoff seminars\n\n\nAbstract\nI will di scuss a gauge theory formulation of a two-dimensional quantum smectic and its relatives\, motivated by their realizations in correlated quantum matt er. The description gives a unified treatment of phonons and topological d efects\, respectively encoded in a pair of coupled gauge fields and corres ponding charges. The charges exhibit subdimensional constrained quantum dy namics and anomalously slow highly anisotropic diffusion of disclinations inside a smectic. This approach gives a transparent description of a multi -stage quantum melting transition of a two-dimensional commensurate crysta l (through an incommensurate crystal -- a supersolid) into a quantum smect ic\, that subsequently melts into a quantum nematic and isotropic superflu ids\, all in terms of a sequence of Higgs transitions.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Venkatesa Chandrasekaran (Berkeley) DTSTART:20201116T193000Z DTEND:20201116T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/20 DESCRIPTION:Title: Gravity dual of Connes cocycle flow\nby Venkatesa Chandraseka ran (Berkeley) as part of Kadanoff seminars\n\n\nAbstract\nGravity dual of Connes cocycle flow\, Venkatesa Chandrasekaran\, Berkley\nModular flow of fers a wealth of insights into both quantum field theory and holography. I ts connection to gravity has implications for understanding bulk reconstru ction and boundary entanglement. In this talk\, I will further explore thi s connection by studying a regularized version of one-sided modular flow: the Connes Cocycle (CC) flow. I will define the “kink transform” as a one-sided boost of bulk initial data about the Ryu-Takayanagi surface of a boundary cut. For a flat cut\, I will demonstrate that the resulting Whee ler-DeWitt patch is the bulk dual to the boundary state obtained by CC flo w across the cut. I will do so by verifying that the kink transform is con sistent with known properties of operator expectation values and subregion entropies under CC flow. Moreover\, I will show that CC flow generates a stress tensor shock at the cut\, controlled by a shape derivative of the e ntropy. I will demonstrate that the kink transform reproduces this shock h olographically through a gravitational shock. I will also discuss the rela tionship to one-sided modular flow and JLMS.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/20/ END:VEVENT BEGIN:VEVENT SUMMARY:Brian Swingle (University of Maryland) DTSTART:20201130T193000Z DTEND:20201130T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/21 DESCRIPTION:Title: Hydrodynamics and the Spectral Form Factor\nby Brian Swingle (University of Maryland) as part of Kadanoff seminars\n\n\nAbstract\nHydro dynamics and the Spectral Form Factor\, Brian Swingle\, University of Mary land\nEnsembles of quantum chaotic systems are expected to exhibit random matrix universality in their energy spectrum. The presence of this univers ality can be diagnosed by looking for a linear in time 'ramp' in the spect ral form factor\, but for realistic systems this feature is typically only visible after a sufficiently long time. I will discuss several developmen ts in our understanding of this intermediate time regime in the spectral f orm factor. First\, I will describe a hybrid system in which the single pa rticle levels are chaotic while the many-body levels are those of non-inte racting particles. In this case\, the linear ramp is replaced by an expone ntial ramp. Interacting deformations of the system can then lead to full m any-body quantum chaos\, but the approach to a linear ramp can be slow due to the presence of nearly conserved modes. Motivated by this problem\, I will present a theory of the spectral form factor in systems with slow mod es and will apply the results to a variety of hydrodynamic systems. Joint work with Mike Winer and Shaokai Jian.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Gabriel Wong (Fudan University) DTSTART:20201123T160000Z DTEND:20201123T170000Z DTSTAMP:20260404T111216Z UID:Kadanoff/22 DESCRIPTION:Title: Entanglement entropy and edge modes in topological string theory< /a>\nby Gabriel Wong (Fudan University) as part of Kadanoff seminars\n\n\n Abstract\nThe Ryu Takayanagi formula identifies the area of boundary ancho red extremal surfaces in AdS with the entanglement entropy of the boundary CFT. However the bulk microstate interpretation of the extremal area rema ins mysterious. Progress along this direction requires understanding how to define entanglement entropy in the bulk closed string theory. As a to y model for AdS/CFT\, we study the entanglement entropy of closed strings in the topological A model in the context of Gopakumar Vafa duality. We give a self consistent factorization of the closed string Hilbert space wh ich leads to string edge modes transforming under a q-deformed surface sy mmetry group. Compatibility with this symmetry requires a q-deformed d efinition of entanglement entropy. Using the topological vertex formali sm\, we define the Hartle Hawking state for the resolved conifold and comp ute its q-deformed entropy directly from the closed string reduced density matrix. We find a match with a target space replica calculation using th e proposal of Susskind and Uglum. We then apply the Gopakumar Vafa dual ity to reproduce the closed string entropy from Chern Simons theory using the un-deformed definition of entanglement entropy. Finally we relate non local aspects of our factorization map to analogous phenomenon recentl y found in JT gravity..\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/22/ END:VEVENT BEGIN:VEVENT SUMMARY:Matthias Gaberdiel (ETH Zurich) DTSTART:20210111T193000Z DTEND:20210111T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/23 DESCRIPTION:Title: An exact AdS/CFT duality\nby Matthias Gaberdiel (ETH Zurich) as part of Kadanoff seminars\n\n\nAbstract\nString theory on AdS3 x S3 x T 4 with one unit of NS-NS flux is argued to be exactly dual to the symmetri c orbifold of T4 in the large N limit. The string theory background can be described in terms of a solvable world-sheet theory. This allows one to c ompute the complete single-string spacetime spectrum and thereby demonstra te that it agrees with that of the symmetric orbifold of T4. Furthermore\, the structure of the symmetric orbifold correlators can be reproduced fro m the world-sheet perspective. I will finally also explain how the world-s heet theory can be reconstructed from the symmetric orbifold theory in a G ross-Mende like limit.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/23/ END:VEVENT BEGIN:VEVENT SUMMARY:Mukund Rangamani (UC Davis) DTSTART:20210125T193000Z DTEND:20210125T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/25 DESCRIPTION:Title: Real-time gravitational replicas\nby Mukund Rangamani (UC Dav is) as part of Kadanoff seminars\n\n\nAbstract\nI will discuss real-time p ath integrals in gravitational theories. As applications we will describe the general structure of replica wormhole saddles and exemplify them with some low dimensional examples. Time permitting\, I will also mention\, so me aspects of effective dynamics of open quantum systems with long-term me mory.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Aaron Hui (Cornell) DTSTART:20210201T193000Z DTEND:20210201T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/26 DESCRIPTION:Title: Beyond Ohm’s law—Bernoulli effect and streaming in electron h ydrodynamics\nby Aaron Hui (Cornell) as part of Kadanoff seminars\n\nA bstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Sid Parameswaran (Oxford) DTSTART:20210301T193000Z DTEND:20210301T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/27 DESCRIPTION:by Sid Parameswaran (Oxford) as part of Kadanoff seminars\n\nA bstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/27/ END:VEVENT BEGIN:VEVENT SUMMARY:Yunfeng Jiang (CERN) DTSTART:20210208T193000Z DTEND:20210208T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/28 DESCRIPTION:Title: Dynamical hard rods and TTbar deformation\nby Yunfeng Jiang ( CERN) as part of Kadanoff seminars\n\n\nAbstract\nIn this talk\, I will sh ow that TTbar and a family of more general solvable bilinear deformations have the effect of deforming point particles into hard rods with finite si ze. This can be seen most easily for non-relativistic systems where the nu mber of excitations is conserved. I will discuss this picture from two dif ferent perspectives. In the first part\, I will discuss TTbar deformation of a concrete model\, which is the 1d Bose gas. In the second part\, I wil l provide a 2d gravity interpretation for the TTbar deformation of generic non-relativistic QFTs in the framework of Newton-Cartan geometry. Finally \, I will discuss the physical implications of the hard rod picture.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/28/ END:VEVENT BEGIN:VEVENT SUMMARY:Cheng Chin (U Chicago) DTSTART:20210215T193000Z DTEND:20210215T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/29 DESCRIPTION:Title: Super-resolution microscopy of cold atoms in optical lattices \nby Cheng Chin (U Chicago) as part of Kadanoff seminars\n\n\nAbstract\nSu per-resolution microscopy has revolutionized the fields of chemistry and b iology by resolving features at the molecular level. With cold atoms\, suc h a scheme can be applied to the length scale of atomic wavefunction and t o perform quantum control. Here we report super-resolution imaging based o n nonlinear response of optical pumping. With this technique the atomic de nsity distribution can be imaged with a half-width-at-half-maximum resolut ion of 16(2) nm and a localization precision below 0.5 nm. The short optic al pumping pulse of 1.4 us enables us to resolve fast atomic motion in the lattice. A surprising application of our scheme is the emergence of moir é patterns on the atomic cloud\, which we show to be immensely magnified images of the atomic cloud.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/29/ END:VEVENT BEGIN:VEVENT SUMMARY:Marcel Franz (University of British Columbia) DTSTART:20210222T193000Z DTEND:20210222T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/30 DESCRIPTION:Title: High-temperature topological superconductivity in twisted double layer copper oxide\nby Marcel Franz (University of British Columbia) a s part of Kadanoff seminars\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/30/ END:VEVENT BEGIN:VEVENT SUMMARY:Nathan Benjamin (Princeton) DTSTART:20210308T193000Z DTEND:20210308T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/31 DESCRIPTION:Title: Narain to Narnia\nby Nathan Benjamin (Princeton) as part of K adanoff seminars\n\n\nAbstract\nWe generalize the recent holographic corre spondence between an ensemble average of free bosons in two dimensions\, a nd a Chern-Simons-like theory of gravity in three dimensions\, by Afkhami- Jeddi et al and Maloney and Witten. We find that the correspondence also w orks for toroidal orbifolds\, but we run into difficulties generalizing to K3 and Calabi-Yau sigma models. For the case of toroidal orbifolds\, we e xtend the holographic correspondence to averages of correlation functions of twist operators by using properties of rational tangles in three-dimens ional balls and their covering spaces. Based on work to appear with C. Kel ler\, H. Ooguri\, and I. Zadeh.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/31/ END:VEVENT BEGIN:VEVENT SUMMARY:William Witczak-Krempa (University of Montreal) DTSTART:20210322T183000Z DTEND:20210322T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/32 DESCRIPTION:Title: Cornering the universal shape of fluctuations and entanglement\nby William Witczak-Krempa (University of Montreal) as part of Kadanoff seminars\n\n\nAbstract\nUnderstanding the fluctuations of observables is o ne of the main goals in physics. We investigate such fluctuations when a s ubregion of the full system can be observed\, focusing on geometries with corners. We report that the dependence on the opening angle is super-unive rsal: up to a numerical prefactor\, this function does not depend on anyth ing\, provided the system under study is uniform\, isotropic\, and correla tions do not decay too slowly. The prefactor contains important physical i nformation: we show in particular that it gives access to the long-wavelen gth limit of the structure factor. We illustrate our findings with several examples: classical fluids\, fractional quantum Hall (FQH) states\, scale invariant quantum critical theories\, and metals. Finally\, we discuss co nnections with the entanglement entropy\, including new results for Laughl in FQH states. Ref: arXiv:2102.06223\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/32/ END:VEVENT BEGIN:VEVENT SUMMARY:Andrea Guerrieri (ICTP-SAIFR\, Sao Paulo) DTSTART:20210329T183000Z DTEND:20210329T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/33 DESCRIPTION:by Andrea Guerrieri (ICTP-SAIFR\, Sao Paulo) as part of Kadano ff seminars\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/33/ END:VEVENT BEGIN:VEVENT SUMMARY:Herman Verlinde (Princeton) DTSTART:20210405T183000Z DTEND:20210405T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/34 DESCRIPTION:Title: Towards a string dual of SYK\nby Herman Verlinde (Princeton) as part of Kadanoff seminars\n\n\nAbstract\nIn this talk I'll present a pr oposal for a string realization of the SYK model as the world-line theory of Q FZZT branes in (p\,1) minimal string theory. Starting from the two-ma trix model description of the minimal string\, I show that the FZZT brane partition function takes the form of a matrix version of the SYK model. I' ll then describe how time emerges upon taking the continuum limit. I'll br iefly comment on possible implications of our result for the string dual i nterpretation of the SYK model and for the role of ensemble averaging in l ow dimensional holography.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/34/ END:VEVENT BEGIN:VEVENT SUMMARY:Ilya Esterlis (Harvard) DTSTART:20210412T183000Z DTEND:20210412T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/35 DESCRIPTION:Title: Large N theory of critical Fermi surfaces\nby Ilya Esterlis ( Harvard) as part of Kadanoff seminars\n\n\nAbstract\nI will discuss recent work on a large-N theory of critical Fermi surfaces in two dimensions. Th e theory applies directly to the onset of Ising order in a Fermi liquid\, and is easily generalized to other forms of order. By employing random cou plings in flavor-space while retaining spatial translation invariance\, we find the large-N saddle point equations are the same as those appearing i n other contexts\; e.g.\, Eliashberg-like theories\, and our approach ther efore provides a systematic framework for assessing and going beyond such theories. I will also discuss the the large-N phase diagram of the system away from criticality\, and show that the ordered side is characterized by a regime of unusually strong thermal fluctuations. Time permitting\, I wi ll also review the behavior of various fermion bilinear operators\, which can be used to diagnose the instabilities of the critical Fermi surface.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/35/ END:VEVENT BEGIN:VEVENT SUMMARY:Hank Lamm (Fermilab) DTSTART:20210419T183000Z DTEND:20210419T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/36 DESCRIPTION:Title: Quantum Simulations for High Energy Physics\nby Hank Lamm (Fe rmilab) as part of Kadanoff seminars\n\n\nAbstract\nThe advent of quantum computation presents the opportunity to solve questions in high energy phy sics which are inaccessible to classical computation such as real-time evo lution and the equation of state at finite density. In order to take advan tage of this new resource\, a number of theoretical and computational hurd les will need to be addressed. In this talk\, I will discuss the state of the art research being performed in HEP and outstanding questions that re quire our attention going forward\, focusing on digitization of lattice ga uge theories and extracting physical results that demonstrate practical qu antum advantage.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/36/ END:VEVENT BEGIN:VEVENT SUMMARY:Anatoly Dymarsky (University of Kentucky) DTSTART:20210426T183000Z DTEND:20210426T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/37 DESCRIPTION:Title: Quantum codes\, conformal field theory\, and holography\nby A natoly Dymarsky (University of Kentucky) as part of Kadanoff seminars\n\n\ nAbstract\nClassical error correcting codes are related to special lattice s\, which give rise to chiral CFTs. Recently this story was generalized to non-chiral theories. In this case quantum codes give rise to Narain latti ces and a special family of Narain theories which we dub code CFTs. Some o f these code theories maximize the spectral gap\, making connection with t he conformal bootstrap program. From the holographic point of view\, code CFTs form an ensemble which provides a simplified model for the recently i ntroduced duality between ensembles of boundary theories and quantum gravi ty in the bulk. In this talk I will first describe the mapping between qua ntum codes and Narain theories\, and then discuss examples of optimal CFTs which maximize the spectral gap. In the second part of the talk I will di scuss the ensemble of code theories and several lessons they presumably te ach us about the ensemble of all Narain theories and its holographic descr iption.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/37/ END:VEVENT BEGIN:VEVENT SUMMARY:Shu-Heng Shao (IAS) DTSTART:20210503T183000Z DTEND:20210503T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/38 DESCRIPTION:Title: Obstructions to Gapped Boundaries from Three-Manifold Invariants< /a>\nby Shu-Heng Shao (IAS) as part of Kadanoff seminars\n\n\nAbstract\nWe derive new obstructions to a 2+1d bosonic TQFT (such as the Chern-Simons theory) admitting a gapped boundary. Each such obstruction is labeled by a closed three-manifold\, and it arises as the phase of the Reshetikhin–T uraev invariant. Using these new obstructions and earlier results on this subject\, we prove the following. \n(1) An abelian bosonic TQFT admits a g apped boundary iff a finite list of certain "higher central charges" vanis h. \n(2) No power of the Fibonacci anyon (a.k.a. the (G2)_1 Chern-Simons t heory) admits a gapped boundary. \nThis talk will be based on work in prog ress with J. Kaidi\, Z. Komargodski\, K. Ohmori\, S. Seifnashri.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/38/ END:VEVENT BEGIN:VEVENT SUMMARY:Mark Mezei (Stony Brook) DTSTART:20210510T183000Z DTEND:20210510T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/39 DESCRIPTION:Title: Effective field theories for quantum chaos\nby Mark Mezei (St ony Brook) as part of Kadanoff seminars\n\n\nAbstract\nQuantum chaotic dyn amics is associated to diverse physical phenomena and signatures. In this talk\, we describe progress in building effective theories for three of th ese: the growth of operators\, the pole skipping phenomenon\, and thermali zation through the lens of entanglement entropy. We uncover their interpla y by showing that the butterfly velocity plays an important role in all th ree manifestations of chaos. The discussion is informed by results from Ad S/CFT and from models of SYK type.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/39/ END:VEVENT BEGIN:VEVENT SUMMARY:Ethan Dyer and Guy Gur-Ari (Google) DTSTART:20210517T193000Z DTEND:20210517T203000Z DTSTAMP:20260404T111216Z UID:Kadanoff/40 DESCRIPTION:Title: The role of scale in deep neural networks\nby Ethan Dyer and Guy Gur-Ari (Google) as part of Kadanoff seminars\n\n\nAbstract\nModern de ep learning has made remarkable progress across a wide variety of domains. A key ingredient to this success has been increasingly big models trained on increasingly large datasets. I will discuss theoretical and empirical work attempting to understand how performance improves with scale and dist inguishing problems which can be solved by scale alone from those where ne w ideas are needed.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/40/ END:VEVENT BEGIN:VEVENT SUMMARY:Zhenbin Yang (Stanford) DTSTART:20210524T183000Z DTEND:20210524T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/41 DESCRIPTION:Title: Wormholes and Unitarity of Black Hole Evolution Process\nby Z henbin Yang (Stanford) as part of Kadanoff seminars\n\n\nAbstract\nI will discuss a working progress on understanding small effects associated to un itarity of black hole evolution process using wormhole geometries. Based o n collaboration with Douglas Stanford and Shunyu Yao.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/41/ END:VEVENT BEGIN:VEVENT SUMMARY:Sandipan Kundu (Johns Hopkins University) DTSTART:20210531T183000Z DTEND:20210531T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/42 DESCRIPTION:Title: Swampland Conditions from CFT\nby Sandipan Kundu (Johns Hopki ns University) as part of Kadanoff seminars\n\n\nAbstract\nThere are effec tive field theories that cannot be embedded in any UV complete theory. I w ill discuss precise bounds on the IR coupling constants of higher derivati ve interactions from UV consistency. In particular\, I will explain how to systematically derive constraints on higher derivative coupling of scalar effective field theories\, with and without dynamical gravity\, in anti-d e Sitter spacetime with large radius by only requiring that the dual CFT o beys the well-established conformal bootstrap axioms. Hence\, this set-up avoids many of the loopholes of flat space S-matrix based arguments that l ead to similar bounds. As an application\, I will use this framework to im pose constraints on the low energy effective action associated with unitar y RG flows in 4d with a broken global U(1) symmetry in the UV.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/42/ END:VEVENT BEGIN:VEVENT SUMMARY:Matthew Lapa (University of Chicago) DTSTART:20210607T183000Z DTEND:20210607T193000Z DTSTAMP:20260404T111216Z UID:Kadanoff/43 DESCRIPTION:Title: Momentum occupation number bounds for interacting fermions\nb y Matthew Lapa (University of Chicago) as part of Kadanoff seminars\n\n\nA bstract\nI will present rigorous bounds on the momentum occupation numbers in translation invariant free fermion models perturbed by Hubbard interac tions and a non-uniform potential. In particular\, at finite temperature I will present a bound on the deviation of the momentum occupation numbers from the non-interacting Fermi-Dirac distribution. Among other things\, th is bound shows that the momentum distribution is very close to that of a l ow-temperature free Fermi gas in the regime where interaction strength << kT << Fermi energy. This work is motivated by Luttinger’s theorem and re lated recent work on the momentum space picture of interacting fermions. W hile those results are interesting\, their derivations rely on various ass umptions\, and such strong results are unlikely to hold for generic models of interacting fermions. In contrast to this situation\, the results that I will present hold for concrete models and can serve as a useful startin g point for understanding the physics of interacting fermions.\n LOCATION:https://stable.researchseminars.org/talk/Kadanoff/43/ END:VEVENT END:VCALENDAR