Fermionic one-body entanglement as a thermodynamic resource

TL;DR

This paper demonstrates that fermionic entanglement, despite superselection rules, can serve as a genuine quantum resource in thermodynamic processes, enabling tasks impossible for separable states.

Contribution

It shows that fermionic entanglement can be operationally accessible and useful in thermodynamics, clarifying its role as a quantum resource despite superselection constraints.

Findings

Fermionic entanglement can be used as a thermodynamic resource.

Entanglement enables tasks forbidden for separable states.

Quantum thermodynamics clarifies the operational meaning of fermionic entanglement.

Abstract

There is ongoing controversy about whether a coherent superposition of the occupied states of two fermionic modes should be regarded entangled or not, that is, whether its intrinsic quantum correlations are operationally accessible and useful as a resource. This has been questioned on the basis that such an entanglement cannot be accessed by local operations on individual modes due to the parity superselection rule which constrains the set of physical observables. In other words, one cannot observe violations of Bell's inequality. Here we show, however, that entanglement of a two-mode fermionic state can be used as a genuine quantum resource in open-system thermodynamic processes, enabling one to perform tasks forbidden for separable states. We thus demonstrate that quantum thermodynamics can shed light on the nature of fermionic entanglement and the operational meaning of the different notions used to define it.