Fundamental limits for cooling of linear quantum refrigerators

TL;DR

This paper establishes fundamental quantum limits on cooling in linear quantum refrigerators, demonstrating that non-resonant excitation creation prevents reaching absolute zero, thus confirming the third law of thermodynamics.

Contribution

It provides exact results for heat flow in driven linear quantum systems, revealing a quantum heating mechanism that enforces the third law beyond weak coupling approximations.

Findings

Non-resonant excitation creation dominates at low temperatures.

The third law of thermodynamics is validated in quantum regimes.

Exact heat flow results go beyond traditional approximations.

Abstract

We study the asymptotic dynamics of arbitrary linear quantum open systems which are periodically driven while coupled with generic bosonic reservoirs. We obtain exact results for the heat flowing into the network, which are valid beyond the usual weak coupling or Markovian approximations. We prove the validity of the dynamical third law of thermodynamics (Nernst unattainability principle), showing that the ultimate limit for cooling is imposed by a fundamental heating mechanism which becomes dominant at low temperatures: the non resonant creation of pairs of excitations in the reservoirs induced by the driving field. This quantum effect, which is missed in the weak coupling approximation, restores the unattainability principle whose validity was recently challenged.