Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.
To add your name to the Quantum Lunch email list, contact Ellie Vigil

Thursday, December 1, 2011
12:30 PM - 2:00 PM

Speaker: Anatoli Polkovnikov (Boston University)

Technical Host: Adolfo Del Campo

TOPIC: Geometric response and universality of slow quantum dynamics in real and imaginary times

Abstract
In this talk I will describe the response of a quantum system to a slowly changing external coupling of an arbitrary amplitude. I will show that in the leading order in the quench velocity the response of the system is given by the geometric tensor: symmetric part (defining Riemannian metric) in imaginary time and antisymmetric part (Berry curvature) in real time. The latter constitutes a dynamical quantum Hall effect in the coupling space, which I will demonstrate on the example of a quantized response of interacting spin systems to a rotating magnetic field. Then I will argue that near singularities, like quantum phase transitions, where relevant susceptibilities defining the geometric tensor can diverge, the response of the system remains universal and can be described by extending the scaling theory of continuous phase transitions to non-equilibrium settings. I will discuss connections of this scaling theory with the Kibble-Zurek mechanism.