Virtual visit: Dr. Koenraad Schalm
Location
Online
Virtual visit: Dr. Koenraad Schalm – Online Event
Date & Time
September 23, 2021, 1:30 pm – 2:30 pm
Description
We have a very exciting guest speaker coming on Thursday (9/29)! Dr. Koenraad Schalm will be giving the following talk:
Title:
"Energy dynamics, information and heat flow in quantum composite systems and the transition from quantum to classical thermodynamics"
Abstract:
We show how the energy dynamics in quenched cooling between two quantum systems can be understood as a combination of information (quantum entropy) gain and energy relaxation. As entropy is not a conserved quantity its dynamics is faster, but it also requires a energy increase linked to the entropy gain. Counterintuitively this implies an initial energy increase even in the hotter of the two subsystems. This amount of energy in each subsystem is controlled by a universal quantity: its information-free-energy, an improvement of the free energy based on the von Neumann entropy of the reduced density matrix and augmented with the relative entropy compared to the initial thermal state. Only in the limit where the energy relaxation overwhelms the (quantum) information gain does classical thermodynamics where energy immediately flows from hot to cold emerge. Away from this limit, if the systems are decoupled sufficiently shortly afterwards, there is an energy transfer from the outside to the combined system in the amount set by the von Neumann entropy accumulated during joint evolution of both systems. This energy transfer appears as work produced by the quench to decouple the reservoirs. This result provides a possibility of a direct readout of the quantum entanglement dominated von Neumann entropy at low temperature. We use both free fermions, SYK systems and Ising chains with a tunneling contact quench to exhibit these characteristics, and comment on its implications for both black hole evaporation and quantum thermodynamics.