Events

The Center hosts regular seminars and group meetings; look here for announcements. If you would like to receive seminar notifications, please subscribe to kadanoffcenter_events@lists.uchicago.edu.  Additional seminars of interest are hosted through the Particle Theory Group and the Computations in Science Seminar series


Kadanoff Center Seminar

Monday, February 17, 2014
Time: 1:30 p.m.
Location: KPTC 103

Speaker: Erik Verlinde (University of Amsterdam)

Title:  “TBA

 


Kadanoff Center Seminar

Monday, Janurary 13, 2014
Time: 1:30 p.m.
Location: KPTC 103

Speaker: Leonid Glazman (Yale University)

Title:  “Nonlinear Quantum Liquids in one Dimension"

Abstract:   The conventional description of one-dimensional quantum fluids is based on the Luttinger liquid theory. In that theory, the true energy-momentum relation of particles making up the fluid is replaced by a linear one. This simplification is crucial for the theory, and abandoning it has proven to be difficult. The talk presents a breakthrough which allows one to circumvent the difficulty. The new theory describes dynamic responses of a fluid consisting of particles with a generic spectrum. It also provides a pathway for developing kinetic theory of a quantum fluid. The developed new description is applicable to a diverse group of systems, including, for example, electrons in quantum wires, one-dimensional spin liquids, and cold atomic gases in one-dimensional traps.

 

 


Special Kadanoff Center/Computations in Science Seminar

Wednesday, December 11, 2013
Time: 3:00 p.m.
Location: KPTC 103

Speaker: David Huse (Princeton)

Title:  “Thermalization and localization in quantum statistical mechanics

Abstract: Progress in atomic physics and quantum information science has motivated much recent study of the behavior of strongly-interacting many-body quantum systems fully isolated from their environment, and thus undergoing coherent quantum time evolution. What does it mean for such a system to go to thermal equilibrium? I will explain the Eigenstate Thermalization Hypothesis (ETH), which says that each individual exact eigenstate of the system's Hamiltonian is at thermal equilibrium, and which appears to be true for most (but not all) quantum many-body systems. Prominent among the systems that do not obey this hypothesis are quantum systems that are many-body Anderson localized. These "many-body localized" systems can retain local memory of local properties of their initial state for infinite time, and thus do not thermally equilibrate and are of interest for quantum information storage. A key issue here is whether or not the system itself constitutes a "reservoir" that can equilibrate its parts.

 


Special Kadanoff Center/Computations in Science Seminar

Tuesday, December 3, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Xian-Gang Wen, Perimeter Institute

Title:  “Symmetry protected topological order in interacting boson systems”

Abstract: Recently, it was realized that quantum states of matter can be classified as long-range entangled (LRE) states (ie with non-trivial topological order) and short-range entangled (SRE) states (ie with trivial topological order). We find that one can use group cohomology class H^d(G,R/Z) to systematically describe the SRE states with a symmetry G [referred as symmetry-protected trivial (SPT) or symmetry-protected topological (SPT) states] in d-dimensional space-time. We will discuss the physical properties of those SPT states, such as the fractionalization of the quantum numbers of the global symmetry on some designed point defects, and the appearance of fractionalized SPT states on some designed defect lines/membranes. Those physical properties are topological invariants of the SPT states which allow us to experimentally or numerically detect those SPT states, ie to measure the elements in H^d(G, R/Z) that label different SPT states.


Kadanoff Center Seminar

Monday, December 2, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Max Metlitski, University of California

Title:  “A symmetry-respecting topologically-ordered surface phase of 3d electron topological insulators.”

Abstract: A 3d electron topological insulator (ETI) is a phase of matter protected by particle-number conservation and time-reversal symmetry. It was previously believed that the surface of an ETI must be gapless unless one of these symmetries is broken. A well-known symmetry-preserving, gapless surface termination of an ETI supports an odd number of Dirac cones. In this talk, I will show that in the presence of strong interactions, an ETI surface can actually be gapped and symmetry preserving, at the cost of carrying an intrinsic two-dimensional topological order. I will argue that such a topologically ordered phase can be obtained from the surface superconductor by proliferating the flux 2hc/e vortex. The resulting topological order consists of two sectors: a Moore-Read sector, which supports non-Abelian charge e/4 anyons, and an Abelian anti-semion sector, which is electrically neutral. The time-reversal and particle number symmetries are realized in this surface phase in an “anomalous” way: one which is impossible in a strictly 2d system. If time permits, I will discuss related results on topologically ordered surface phases of 3d topological superconductors.

 


Kadanoff Center Seminar

Friday, November 18, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Stefan Janiszewski (University of Washington)

Title:  “Universal Horizons in Non-Relativistic Holography
Abstract: A proposal for a form of non-relativistic holography is justified by considering the global symmetries of generic non-relativistic quantum field theories. The gravity dual is seen to be a form of Horava gravity. Black holes are defined and studied in this theory. Thermodynamic results and possible future directions are presented..

 


Kadanoff Center Seminar

Friday, November 12, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Nick Read (Yale University)

Title:  “Hall Viscosity"
 

 


Kadanoff Center Seminar

Friday, November 11, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Nick Read (Yale University)

Title:  “Real-space and particle entanglement spectra of trial quantum Hall states"
 

 


Kadanoff Center Seminar

Friday, November 1, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Anton Zabrodin (ITEP, Moscow and HSE, Moscow)

Title:  “Large N properties of 2D Coulomb gases
Abstract: We will discuss statistical mechanics of N charged particles in the plane with logarithmic (2D Coulomb) interaction in an external potential and inverse temperature beta. Systems of this type, known also as beta-ensembles, emerge in different physical and mathematical contexts such as fractional quantum Hall effect, viscous flows in the Hele-Shaw cell, random matrices. We will be interested in large N properties of the system at different values of beta. In particular, we will discuss the 1/N expansion of the free energy, the mean density of particles and correlation functions, with the emphasis on some open problems.

 


Kadanoff Center Seminar

Monday, October 28, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: Chaolun Wu (UChicago)

Title:  “Hall Viscosity, Angular Momentum and Parity-Violating Holography
Abstract: Hall viscosity is a parity-odd transport coefficient that arises in many parity-violating systems, and is related to the angular momentum density of the systems. In this talk, I will first give a brief review of parity-violating hydrodynamics, from which the Hall viscosity is defined. Then I will focus on holographic approaches to compute Hall viscosity and angular momentum density for strongly coupled systems. Previous studies on explicit parity-violating holographic models had left a mystery about the relation between these two quantities. In our recent study on holographic p+ip-wave model, which breaks parity only spontaneously by its ground state, we obtained analytic results for both quantities and a simple relation between them, in agreement with previous studies base on non-holographic approaches. This also helps to clarify the mystery regarding the explicit parity-violating models.

 


Kadanoff Center Seminar

Thursday, October 24, 2013
Time: 1:30 p.m.
Location: ACC 211

Speaker: William Witczak-Krempa (Perimeter Institute)

Title:  “The dynamics of quantum criticality: Quantum Monte Carlo and holography
Abstract: Understanding the real time dynamics of systems near quantum critical points at finite temperatures constitutes an important yet challenging problem, especially in 2 spatial dimensions where interactions are strong. To make progress we examine the problem using field theory, numerics and holography. Our main results derive from quantum Monte Carlo simulations for 2 separate realizations of the superfluid-insulator transition of bosons on a lattice: their low-frequency conductivities are found to have the same universal dependence on imaginary frequency and temperature. We then use the structure of the dynamics of conformal field theories described by the holographic gauge/gravity duality to make progress on the difficult task of analytically continuing the Monte Carlo data to real time. Our method yields quantitative and experimentally testable results on the frequency-dependent conductivity at the quantum critical point, and on the spectrum of quasinormal modes in the vicinity of the quantum phase transition. Extensions to other observables and universality classes are discussed.

 


Kadanoff Center Seminar

Monday, October 14, 2013
Time: 3:00 p.m.
Location: ACC 211

Speaker: Tankut Can (UChicago)

Title:  “Singular behavior at the edge of fractional quantum Hall states
Abstract: A distinguishing feature of fractional quantum Hall (FQH) states is a singular behavior of equilibrium densities at boundaries. For Laughlin states, which describe odd integer inverse filling fractions, this behavior manifests as an overshoot in the particle density near a boundary, and has a direct consequence on the dispersion of edge states. In this talk, I will describe an approach which captures this phenomenon using a perturbative expansion around the completely filled Landau level. This technique allows us to extract exact asymptotics of the edge density of a FQH liquid, and ultimately reveal its singular structure.

 


Kadanoff Center Seminar

Monday, October 7, 2013
Time: 3:00 p.m.
Location: ACC 211

Speaker: Andreas Karch (Univ of Washington)

Title:  “Entanglement Entropy for Probe Branes
Abstract: I'll give a prescription for calculating the entanglement entropy in holographic probe brane systems is given. I'll discuss a few simple examples in order to validate the method. As an application, I'll calculate the entanglement for a holographic EPR pair in maximally supersymmetric Yang-Mills theory and discuss implications for the recently proposed ER=EPR correspondence.