Physics (Internal)

The statistics of the work done in quantum quenches

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: A quantum quench is a rapid change in time of a control parameter in the hamiltonian describing a quantum, correlated many body system. In this talk I will discuss a fundamental way to characterize these processes using basic thermodynamic variables and looking at their statistics. I will first elucidate the connection between a classic problem of condensed matter physics, the Fermi edge singularity, a quantity emerging in the context of dephasing, the Loschmidt echo, and the statistics of the work done in a quantum quench. Using this connection, I will then characterize the statistics of the work done on a quantum Ising chain by quenching locally or globally the transverse field, showing that for local quenches starting at criticality, the probability distribution of the work displays an interesting edge singularity. Similar singularities emerge in other quantum critical systems, such as the Dicke model.