Conference

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Universal dynamics and topological order in many-body localized states

Ronen Vosk Weizmann Institute of Science

May 15, 2014

PIRSA:14050082
(Jean-Sebastien Caux) Exact solutions for quenches in 1d Bose gases and quantum spin chains

May 15, 2014

PIRSA:14050081
A Rigorous Result on Many-Body Localization

John Imbrie University of Virginia

May 14, 2014

PIRSA:14050079
Many-body mobility edge in a mean-field quantum spin-glass

Arijeet Pal Harvard University

May 14, 2014

PIRSA:14050078
Localization and topology protected quantum coherence at the edge of 'hot' matter

Ehud Altman University of California, Berkeley

May 14, 2014

PIRSA:14050077
Long-time behavior of periodically driven isolated interacting quantum systems

Luca D'Alessio Boston University

May 13, 2014

PIRSA:14050073
Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy

Fabian Essler University of Oxford

May 13, 2014

PIRSA:14050072
Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion

May 13, 2014

PIRSA:14050071
Dynamical analogue quantum simulators

Jens Eisert Freie Universität Berlin

May 12, 2014

PIRSA:14050068
Quantum Quenches in Thermodynamic Limit

Marcos Rigol Pennsylvania State University

May 12, 2014

PIRSA:14050067
TBA

Eugene Demler Harvard University

May 12, 2014

PIRSA:14050065
Critical Behavior of the Classical XY-model on Fractal Structures

Michelle Przedborski

May 07, 2014

PIRSA:14050060

Universal dynamics and topological order in many-body localized states

Ronen Vosk Weizmann Institute of Science

May 15, 2014

PIRSA:14050082

It has been argued recently that, through a phenomenon of many-body localization, closed quantum systems subject to sufficiently strong disorder would fail to thermalize. In this talk I will describe a real time renormalization group approach, which offers a controlled description of universal dynamics in the localized phase. In particular it explains the ultra-slow entanglement propagation in this state and identifies the emergent conserved quantities which prevent thermalization. The RG analysis also shows, that far from being a trivial dead state, the MBL state admits phase transitions between distinct dynamical phases. For example, I will discuss the universal aspects of a transition between a paramagnetic localized state to one which exhibits spin-glass order. Finally, I will present a development of the RG scheme, defined on an effective coarse grained model, which allows to capture the transition from a many-body localized to a thermalizing state.
(Jean-Sebastien Caux) Exact solutions for quenches in 1d Bose gases and quantum spin chains

May 15, 2014

PIRSA:14050081
A Rigorous Result on Many-Body Localization

John Imbrie University of Virginia

May 14, 2014

PIRSA:14050079

I will discuss a proof of many-body localization for a one-dimensional spin chain with random local interactions. The proof depends on a physically reasonable assumption that limits the amount of level attraction in the system. I construct a sequence of local rotations that completely diagonalizes the Hamiltonian and exhibits the local degrees of freedom.
Many-body mobility edge in a mean-field quantum spin-glass

Arijeet Pal Harvard University

May 14, 2014

PIRSA:14050078

Isolated, interacting quantum systems in the presence of strong disorder can exist in a many-body localized phase where the assumptions of equilibrium statistical physics are violated. On tuning either the parameters of the Hamiltonian or the energy density, the system is expected to transition into the ergodic phase. While the transition at "infinite temperature" as a function of system parameters has been found numerically but, the transition tuned by energy density has eluded such methods.
In my talk I will discuss the nature of the many-body localization-delocalization (MBLD) transition as a function of energy denisty in the quantum random energy model (QREM). QREM provides a mean-field description of the equilibrium spin glass transition. We show that it further exhibits a many-body mobility edge when viewed as a closed quantum system. The mean-field structure of the model allows an analytically tractable description of the MBLD transition. I will also comment on the nature of the critical states in this mean-field model.
This opens the possibility of developing a mean-field theory of this interesting dynamical phase transition.
Localization and topology protected quantum coherence at the edge of 'hot' matter

Ehud Altman University of California, Berkeley

May 14, 2014

PIRSA:14050077

Topological phases are often characterized by special edge states confined near the boundaries by an energy gap in the bulk. On raising temperature, these edge states are lost in a clean system due to mobile thermal excitations. Recently however, it has been established that disorder can localize an isolated many body system, potentially allowing for a sharply defined topological phase even in a highly excited state.I will show this to be the case for the topological phase of a one dimensional magnet with quenched disorder, which features spin one-half excitations at the edges. The time evolution of a simple, highly excited, initial state is used to reveal quantum coherent edge spins. In particular, I will demonstrate, using theoretical arguments and numerical simulation, the coherent revival of an edge spin over a time scale that grows exponentially bigger with system size. This is in sharp contrast to the general expectation that quantum bits strongly coupled to a 'hot' many body system will rapidly lose coherence.
Long-time behavior of periodically driven isolated interacting quantum systems

Luca D'Alessio Boston University

May 13, 2014

PIRSA:14050073

We show that generic interacting quantum systems, which are isolated and finite, periodically driven by sudden quenches exhibit three physical regimes. For short driving periods the Floquet Hamiltonian is well approximated by the time-averaged Hamiltonian, while for long periods the evolution operator exhibits properties of random matrices of a Circular Ensemble (CE). In-between, there is a crossover
regime. We argue that, in the thermodynamic limit and for nonvanishing driving periods, the evolution operator always exhibits properties of CE random matrices. Consequently, driving leads to infinite temperature at infinite time and to an unphysical Floquet Hamiltonian.
Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy

Fabian Essler University of Oxford

May 13, 2014

PIRSA:14050072
Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion

May 13, 2014

PIRSA:14050071
Dynamical analogue quantum simulators

Jens Eisert Freie Universität Berlin

May 12, 2014

PIRSA:14050068

Complex quantum systems out of equilibrium are at the basis of a number of long-standing questions in physics. This talk will be concerned on the one hand with recent progress on understanding how quantum many-body systems out of equilibrium eventually come to rest, thermalise and cross phase transitions, on the other hand with dynamical analogue quantum simulations using cold atoms [1-4]. In an outlook, we will discuss the question of certification of quantum simulators, and will how this problem also arises in other related settings, such as in Boson samplers [5,6]. [1] S. Braun, M. Friesdorf, S. S. Hodgman, M. Schreiber, J. P. Ronzheimer, A. Riera, M. del Rey, I. Bloch, J. Eisert, U. Schneider, arXiv:1403.7199.
[2] M. Kliesch, M. Kastoryano, C. Gogolin, A. Riera, J. Eisert, arXiv:1309:0816.
[3] S. Trotzky, Y.-A. Chen, A. Flesch, I. P. McCulloch, U. Schollwoeck, J. Eisert, I. Bloch, Nature Physics 8, 325 (2012).
[4] A. Riera, C. Gogolin, M. Kliesch, J. Eisert, in preparation (2014).
[5] C. Gogolin, M. Kliesch, L. Aolita, J. Eisert, in preparation (2014) and arXiv:1306.3995.
[6] S. Aaronson, A. Arkhipov, arXiv:1309.7460.
Quantum Quenches in Thermodynamic Limit

Marcos Rigol Pennsylvania State University

May 12, 2014

PIRSA:14050067

Studies of the quantum dynamics of isolated systems are currently providing fundamental insights into how statistical mechanics emerges under unitary time evolution. Thermalization seems ubiquitous, but experiments with ultracold gases have shown that it need not always occur, particularly near an integrable point. Unfortunately, computational studies of generic (nonintegrable) models are limited to small systems, for which arbitrarily long times can be calculated, or short times, for which large or infinite system sizes can be solved. Consequently, what happens in the thermodynamic limit after long times has been inaccessible to theoretical studies. In this talk, we introduce a linked-cluster based computational approach that allows one to address the latter question in lattice systems. We provide numerical evidence that, in the thermodynamic limit, thermalization occurs in the nonintegrable regime but fails at integrability. A phase transition-like behavior separates the two regimes.
TBA

Eugene Demler Harvard University

May 12, 2014

PIRSA:14050065
Critical Behavior of the Classical XY-model on Fractal Structures

Michelle Przedborski

May 07, 2014

PIRSA:14050060

There has been considerable interest in determining whether the universality hypothesis extends to systems which are of non-integer dimension or to systems which are scale invariant (fractals). Specifically research into these types of systems is concerned with determining the relevance of topological properties to their critical phenomena. We have performed Monte Carlo simulations for the XY model on three fractal lattices with different topological properties: the Sierpinski pyramid Menger sponge and Sierpinski carpet. We will give an overview of our results and show that while some properties such as the order of ramification are important in determining the critical behavior of these structures the fractal dimension is not.

Title	Speaker(s)	Date	Talk Type	Info link
Universal dynamics and topological order in many-body localized states	Ronen Vosk	2014-05-15	Conference	View details
(Jean-Sebastien Caux) Exact solutions for quenches in 1d Bose gases and quantum spin chains		2014-05-15	Conference	View details
A Rigorous Result on Many-Body Localization	John Imbrie	2014-05-14	Conference	View details
Many-body mobility edge in a mean-field quantum spin-glass	Arijeet Pal	2014-05-14	Conference	View details
Localization and topology protected quantum coherence at the edge of 'hot' matter	Ehud Altman	2014-05-14	Conference	View details
Long-time behavior of periodically driven isolated interacting quantum systems	Luca D'Alessio	2014-05-13	Conference	View details
Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy	Fabian Essler	2014-05-13	Conference	View details
Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion		2014-05-13	Conference	View details
Dynamical analogue quantum simulators	Jens Eisert	2014-05-12	Conference	View details
Quantum Quenches in Thermodynamic Limit	Marcos Rigol	2014-05-12	Conference	View details
TBA	Eugene Demler	2014-05-12	Conference	View details
Critical Behavior of the Classical XY-model on Fractal Structures	Michelle Przedborski	2014-05-07	Conference	View details

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Universal dynamics and topological order in many-body localized states

(Jean-Sebastien Caux) Exact solutions for quenches in 1d Bose gases and quantum spin chains

A Rigorous Result on Many-Body Localization

Many-body mobility edge in a mean-field quantum spin-glass

Localization and topology protected quantum coherence at the edge of 'hot' matter

Long-time behavior of periodically driven isolated interacting quantum systems

Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy

Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion

Dynamical analogue quantum simulators

Quantum Quenches in Thermodynamic Limit

TBA

Critical Behavior of the Classical XY-model on Fractal Structures

Universal dynamics and topological order in many-body localized states

(Jean-Sebastien Caux) Exact solutions for quenches in 1d Bose gases and quantum spin chains

A Rigorous Result on Many-Body Localization

Many-body mobility edge in a mean-field quantum spin-glass

Localization and topology protected quantum coherence at the edge of 'hot' matter

Long-time behavior of periodically driven isolated interacting quantum systems

Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy

Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion

Dynamical analogue quantum simulators

Quantum Quenches in Thermodynamic Limit

TBA

Critical Behavior of the Classical XY-model on Fractal Structures