John Imbrie
(University of Virginia)
13/06/2016 10:15
Invited talk
For a weakly interacting quantum spin chain with random local interactions, we prove that many-body localization follows from a physically reasonable assumption that limits the extent of level attraction in the statistics of eigenvalues. In a KAM-style construction, a sequence of local unitary transformations is used to diagonalize the Hamiltonian by deforming the initial tensor-product basis...
Francois Huveneers
(Paris Dauphine, CEREMADE)
13/06/2016 11:00
Invited talk
In this talk, I will consider a fully MBL system coupled to an imperfect bath, representing a small (microscopic or mesoscopic) chunk of an ergodic material. This set-up arrises naturally since disorder fluctuations naturally lead to the formation of such spots inside the MBL phase. My aim is to describe the intermediate region arising in the vicinity of the ergodic spot. I will provide a...
Simone Warzel
(Technical University of Munich)
13/06/2016 12:15
Invited talk
In view of the woefully short list of rigorous results on disordered systems with interaction, limiting or integrable model systems present a testing ground for numerical works, conjectures and ideas. In the bosonic case, the limiting case of hard-core repulsive interaction is such an example: in the lattice set-up this amounts to studying the XY-spin Hamiltonian with a random magnetic field,...
Alain Aspect
(Institut d'Optique, Palaiseau, France)
13/06/2016 14:30
Invited talk
In the early 1980's, observation of a magneto-resistance anomaly in metallic thin films was attributed to the phenomenon of weak localization of electrons and to time-reversal symmetry breaking due to a magnetic field acting upon charged particles.
We have observed weak localization of ultra-cold atoms in a 2D configuration, placed in a disordered potential created by a laser speckle. In...
Robin Kaiser
(CNRS and INLN, Nice)
13/06/2016 15:15
Invited talk
The quest for Anderson localization of light is at the center of many experimental and
theoretical activities. Cold atoms have emerged as interesting quantum system to study coherent transport
properties of light. Initial experiments have established that dilute samples with large
optical thickness allow studying weak localization of light.
The goal of our research is to study coherent...
Vladimir Kratsov
(ICTP Trieste)
13/06/2016 17:15
Invited talk
We show that the Anderson model on the random regular graph (RRG) possesses two transitions. One of them is the usual localization transition that happens at the disorder
strength W=W_{c} \approx 18.2 and the other one is the first order transition between the extended ergodic and non-ergodic (multifractal) states. It happens at W=W_{E}\approx 10.0 and manifests itself in the sharp jump in...
Immanuel Bloch
(Max Planck Institute of Quantum Optics, Garching, Germany Ludwig-Maximilians University, Munich, Germany)
14/06/2016 09:30
Invited talk
A fundamental assumption in statistical physics is that generic closed quantum many-body systems thermalise under their own dynamics. Recently, the
emergence of many-body localised (MBL) systems has questioned this concept, challenging our understanding of the connection between statistical physics and quantum mechanics. In my talk, I will report on several recent experiments carried out in...
Dimitry Abanin
(University of Geneva)
14/06/2016 10:15
Invited talk
Periodic driving provides an efficient way of quantum control. In particular, in recent experiments driving was used to realize topological Bloch bands in optical lattices. In this talk, I will present several rigorous results regarding periodically driven many-body systems. First, I will derive strong bounds on the heating rates of generic many-body systems. I will introduce a new approach...
Romain Vasseur
(University of California Berkeley)
14/06/2016 11:30
Invited talk
In this talk, I will describe some general constraints on the existence of many-body localized (MBL) phases in the presence of global symmetries. I will start by considering the example of the random-bond XXZ spin chain and argue using real space renormalization group techniques that interactions drive the system into a many-body localized spin glass phase with spontaneously broken...
Jens Bardarson
(MPI-PKS, Dresden)
14/06/2016 12:15
Invited talk
We show that the one-particle density matrix ρ can be used to characterize the interaction-driven many-body localization transition in closed fermionic systems. The natural orbitals (the eigenstates of ρ) are localized in the many-body localized phase and spread out when one enters the delocalized phase, while the occupation spectrum (the set of eigenvalues of ρ) reveals the distinctive...
David Reichman
(Columbia University)
14/06/2016 14:30
Invited talk
In this talk the transition of a quantum system from an ergodic to a non-ergodic state is discussed from several different perspectives. In the first part of the talk I discuss the formation of quantum glasses in liquids with no quenched disorder. It is shown that weak quantum fluctuations can enhance the loss of ergodicity. In the second part of the talk I discuss many-body localization...
Markus Muller
(Paul Scherr Institute and ICTP)
14/06/2016 15:15
Invited talk
I explore the possibility that translationally invariant quantum many body systems may undergo a transition to a localized phase where ergodicity and translational invariance break down spontaneously. This phenomenon could be regarded as an interaction-induced many-body localization on configurational (self-generated) disorder.
I will argue that such quantum glasses are indeed stable to...
Lev Ioffe
(Rutgers University and CNRS, LPTHE UPMC)
14/06/2016 17:15
Invited talk
Christopher Monroe
(JQI and University of Maryland)
15/06/2016 09:30
Invited talk
rapped atomic ions represent a very clean platform for the quantum simulation of interacting spin models. When spin-dependent optical dipole forces are applied to a collection of trapped ions, an effective long-range quantum magnetic interaction arises, with reconfigurable and tunable graphs that are determined by the spectrum of the laser forces. Recent experiments have implemented transverse...
Alberto Rosso
(CNRS and LPTMS)
15/06/2016 11:30
Invited talk
A generic isolated quantum system has two possible fates at long times:
it thermalizes or it remains many-body localized close to its initial state. So far only few systems showing experimentally relevant consequences of many-body localization have been reported in cold atoms and in trapped ions. In this talk, we show that the phenomenon {\em is} relevant in quantum magnets, and we discuss...
Maksym Serbyn
(University of California Berkeley)
15/06/2016 12:15
Invited talk
Many body localization allows quantum systems to escape thermalization via emergence of extensive number of conserved quantities. I will demonstrate how the breakdown of local conserved quantities allows to probe the delocalization transition. Using statistics of matrix elements of local operators, I will define an analogue of many-body Thouless conductance which probes the response of the...
David Pekker
(University of Pittsburgh)
15/06/2016 14:30
Invited talk
The conventional formulation of the renormalization group, which works by iteratively “integrating” out high energy degrees of freedom, is aimed at describing states near the top or bottom of a spectrum. Wegner’s flow equation is an alternative formulation that is aimed at describing the entire spectrum by iteratively decoupling degrees of freedom of the system that have large energy...
Jens Eisert
(Free University, Berlin)
15/06/2016 15:15
Invited talk
The phenomenon of many-body localisation received a lot of attention
recently, both for its implications in condensed-matter physics of
allowing systems to be an insulator even at non-zero temperature as
well as - maybe most importantly - in the context of the foundations
of quantum statistical mechanics, providing examples of systems
showing the absence of thermalisation following...
Fabien Alet
(CNRS and Universite' de Toulouse, LPT)
15/06/2016 16:00
Invited talk
