The quantum Carnot engine and its quantum signature

by Prof. Ronnie Kosloff

Institute Of Chemistry The Hebrew University, Jerusalem

at Physics Colloquium

Tue, 19 Nov 2019, 15:30
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015

Abstract

Quantum thermodynamics follows the tradition of learning by example. The Carnot cycle would
be a primary candidate. The attempts to model the four stroke quantum Carnot cycle failed due
to the difficulty to model the isothermal branches, where the working medium is driven while in
contact to the thermal bath. Motivated by this issue we derived a time dependent Non Adiabatic
Master Equation (NAME) with a fixed driving protocol. This master equation is consistent with
thermodynamic principles. We then were able to generalize to protocols with small acceleration
with respect to the fixed fast protocols. This approach was confirmed experimentally in a driven
Ytterbium ion in a Paul trap. Using this construction we are able to find shortcuts to an isothermal
transformation. Unlike unitary transformations the map changes entropy. After this journey, we
are able close a Carnot like cycle in finite time and explore its performance. In the limit of short
cycle times we are able to locate a quantum region of operation. Once the global coherence is
eliminated the engines cannot operate. The nonadiabatic drive forces us to reconsider the quantum
thermodynamical definition of heat and work.

Created on 28-10-2019 by Bar, Ilana (ibar)
Updaded on 28-10-2019 by Bar, Ilana (ibar)