Power enhancement of heat engines via correlated thermalization in multilevel systems

TL;DR

This paper demonstrates that degeneracy in multilevel quantum heat engines can significantly boost power output without affecting efficiency, highlighting level degeneracy as a valuable thermodynamic resource.

Contribution

It reveals that level degeneracy enhances power in quantum heat engines without impacting efficiency, and coherence is not necessary for this enhancement.

Findings

Maximal power of a degenerate three-level engine equals two independent two-level engines.

Power enhancement scales as (N-1) for N-level systems.

Coherence is not essential; multiple thermalization pathways suffice.

Abstract

We analyze a heat machine based on a periodically-driven quantum system permanently coupled to hot and cold baths. It is shown that the maximal power output of a degenerate $V$-type three-level heat engine is that generated by two independent two-level systems. For $N$ levels, this maximal enhancement is $(N-1)$-fold. Hence, level degeneracy is a thermodynamic resource that may effectively boost the power output. The efficiency, however, is not affected. We find that coherence is not an essential asset in multilevel-based heat machines. The existence of multiple thermalization pathways sharing a common ground state suffices for power enhancement.