Quantum statistical enhancement of the performance of multiple quantum heat engines

On 27 May 2020, an international collaboration lead by a ZJU faculty member has published their work on quantum heat engines in Physical Review Letters.

Heat engines are devices that convert thermal energy into mechanical work in a consecutive manner. Advances in technology so far have enabled us to downsize the heat engines and recent development spurred the fabrication of heat engines at the submicron to nanoscale. Especially in the last decade, great attention has been paid to so-called quantum heat engines (QHEs), microscopic heat engines whose working substance is a quantum system. Since the behavior of the working substance is governed by quantum mechanics, QHEs are expected to show exotic properties, which cannot be obtained in conventional macroscopic counterparts governed by classical mechanics.

While the performance of QHEs are commonly accessed for a single engine through a single cycle without coupling to a load, their actual performance when they are coupled to an external system to extract work is a non-trivial and important issue since QHEs are susceptible to such outcoupling due to their smallness. The international collaboration lead by a ZJU faculty member, Gentaro Watanabe, and Prof. B. Prasanna Venkatesh from IIT Gandhinagar in India has been working on addressing this issue last few years.

The team considered an ensemble of multiple indistinguishable heat engines. While such a setting does not make sense for macroscopic heat engines, if each engine consists of, e.g., a single atom, this problem becomes physically relevant. They have discovered that, when multiple indistinguishable bosonic QHEs are coupled to an external system, the work output exhibits an enhancement arising from permutation symmetry in the ensemble. Such an enhancement due to the quantum statistics of the engines is a genuine quantum effect which is absent for classical heat engines. The predicted enhancement of the work output from multiple indistinguishable heat engines to a generic external system is readily testable with current or near-future experimental realizations of QHEs.

This work has been supported by Zhejiang Provincial Natural Science Foundation Key Project, by NSFC, and by the Fundamental Research Funds for the Central Universities. Gentaro Watanabe is the first and corresponding author.

Gentaro Watanabe, B. Prasanna Venkatesh, Peter Talkner, Myung-Joong Hwang, and Adolfo del Campo, Quantum Statistical Enhancement of the Collective Performance of Multiple Bosonic Engines, Phys. Rev. Lett. 124, 210603 (2020).