Most energetic passive states

TL;DR

This paper identifies and characterizes the most energetic passive states, which maximize energy for a given entropy, providing fundamental bounds for quantum thermodynamics.

Contribution

It introduces the concept of most energetic passive states, expanding the understanding of extremal properties within passive states in quantum thermodynamics.

Findings

Passive states that maximize energy for a given entropy are identified.

These states minimize entropy at fixed energy, serving as bounds in quantum thermodynamics.

The results have implications for finite-dimensional quantum systems.

Abstract

Passive states are defined as those states that do not allow for work extraction in a cyclic (unitary) process. Within the set of passive states, thermal states are the most stable ones: they maximize the entropy for a given energy, and similarly they minimize the energy for a given entropy. Here we find the passive states lying in the other extreme, i.e., those that maximize the energy for a given entropy, which we show also minimize the entropy when the energy is fixed. These extremal properties make these states useful to obtain fundamental bounds for the thermodynamics of finite-dimensional quantum systems, which we show in several scenarios.