Speaker: Erik Aurell

Title:
Quantum heat and path integrals

Abstract:
Quantum fluctuation relations in the style of Kurchan rely on measuring 
the energy of system before and after a process. Analogously, quantum heat 
can be defined as the change of energy of a bath, or baths, during a 
process. I will discuss how the distribution function of this quantity can 
be computed in a path integral formulation originally developed by Feynman 
and Vernon for the open system quantum state. It is hence a functional of 
the system only, the bath or baths having been integrated out.

If time allows I will consider the special case of thermal power of the 
heat flow through a two-state system (a qubit), interacting with two baths 
as in the spin-boson problem. I will then discuss the qualitative 
similarities and differences between when the qubit interacts weakly or 
strongly with the baths. 

Most of the material in the talk can be found in the two papers

E Aurell "Characteristic functions of quantum heat with baths at 
different temperatures", Physical Review E vol 97 p 062117 (2018)
E Aurell and F Montana "Thermal power of heat flow through a qubit" 
arXiv:1901.05896 (2019)