ESPCI web site
Friday October 27 at 2:00 pm (Paris time)}
ESPCI, Room Charpak, entrance building
Extending the laws of thermodynamics for arbitrary autonomous quantum systems
Understanding quantum setups with the concepts of nonequilibrium thermodynamics has attracted a lot of attention over the last decades. The emerging field of Quantum Thermodynamics is motivated by the recent ability to manipulate elementary open quantum systems to realize quantum engine cycles. Its core concepts build on the advances in nonequilibrium thermodynamics developed in the 90s to describe molecular engines, which managed to expressed fundamental constraints on the energy flows valid far from equilibrium and from the thermodynamic limit.
By analyzing engines based on quantum systems, it was possible to show first occurrences of quantum advantages in motor and refrigerator performances exploiting properties specific to the quantum world such as coherent superpositions, entanglement, indistinguishable particles... Other quantum phenomena such as the backaction of a quantum measurement have been revealed as new sources of irreversibility, but also new resources able to fuel engines.
More generally, a goal of the community is to express the fundamental constraints on energy flows valid at the quantum scale — that is the quantum version of the laws of nonequilibrium thermodynamics — to understand the limitations on such engines and optimize their performances, but also to find new tools to characterize complex quantum systems. While consistent frameworks have been proposed to do so for quantum open systems coupled to classical work and heat sources, it is desirable to understand energy exchange between quantum systems. This is in particular necessary to address quantum batteries or nanoscale autonomous machines which hold the promises of interesting advantages.
In this seminar, I will present a formalism we recently introduced to address this situation. We show that any quantum system can be understood as a hybrid source of heat and work, the former being constrained by a quantum version of the Second law of thermodynamics involving an apparent temperature related to its Von Neuman entropy. Ideal cases of pure work and heat sources can be retrieved, while the formalism also allows us to analyze situations far from classical thermodynamics, such elementary engines based only on small quantum systems as heat and work sources. Our formalism provides a basis to analyze and optimize energy transfers occurring in quantum systems, valid at any scale and any coupling intensity.