This week's seminars announced by CMSP Section

[Cond.Matt. & Stat.Mech.Section]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR

 

Tuesday, 4 December   -   11:00 a.m.




SISSA, Santorio Building,  Room 134 (1st Floor)

 


M. FAGOTTI   ( Oxford University )



" Relaxation after a sudden quench:  Insights from exactly solvable models"



Abstract


I consider the time evolution of observables and reduced density matrices after a sudden
quench of a Hamiltonian parameter in one dimensional systems. I discuss the issue of
relaxation and show quite generally that if subsystems relax and can be described in terms
of a statistical ensemble, dynamical correlations are described by the same ensemble as well.
Then I consider quenches in the transverse field Ising chain, where many exact results have
been recently obtained. I focus on the approach to the stationary state (which, in the specific
case, is a generalized Gibbs ensemble) and discuss the relation between time averages and
late time dynamics.



===



SEMINAR on  Disorder and strong electron correlations


Thursday, 6 December-  11:30 a.m.

 
Luigi Stasi Seminar Room,  Leonardo Building - first floor

 

Matthew S. FOSTER   ( Rice University, Houston )

 

"Quantum quench in p+ip superfluids:  Non-equilibrium topological gapless state"



Abstract

 
Ground state "topological protection" has emerged as a main theme in quantum condensed matter physics.  A key question is the robustness of physical properties including topological quantum numbers to perturbations such as disorder or non-equilibrium driving.

In this work we investigate the dynamics of a p+ip superfluid following a zero temperature quantum quench. The model describes a 2D topological superconductor with a non-trivial (trivial) BCS (BEC) phase. We work with the full interacting BCS Hamiltonian, which we solve exactly in the thermodynamic limit using classical integrability. The non-equilibrium phase diagram is obtained for generic quenches.  A large region of the phase diagram describes strong to weak-pairing quenches wherein the order parameter vanishes in the long-time limit, due to pair fluctuations.  Despite this, we find that the topological winding number survives for quenches in this regime, leading to the prediction of a "gapless topological" state.

We discuss potential realizations, including a proximity effect quench on the surface of 3D topological insulator.