Probabilistically Violating the First Law of Thermodynamics in a Quantum Heat Engine

TL;DR

This paper demonstrates that quantum fluctuations can probabilistically violate the first law of thermodynamics in a quantum heat engine, challenging traditional thermodynamic principles at the quantum level.

Contribution

It reveals that quantum mechanics can cause violations of the first law due to constraints on heat and work knowledge, supported by a circuit QED case study.

Findings

Probabilistic violations of the first law observed

Violations linked to quantum signatures like negative quasi-probabilities

First law may not hold in individual quantum experimental runs

Abstract

Fluctuations of thermodynamic observables, such as heat and work, contain relevant information on the underlying physical process. These fluctuations are however not taken into account in the traditional laws of thermodynamics. While the second law is extended to fluctuating systems by the celebrated fluctuation theorems, the first law is generally believed to hold even in the presence of fluctuations. Here we show that in the presence of quantum fluctuations, also the first law of thermodynamics may break down. This happens because quantum mechanics imposes constraints on the knowledge of heat and work. To illustrate our results, we provide a detailed case-study of work and heat fluctuations in a quantum heat engine based on a circuit QED architecture. We find probabilistic violations of the first law and show that they are closely connected to quantum signatures related to negative quasi-probabilities. Our results imply that in the presence of quantum fluctuations, the first law of thermodynamics may not be applicable to individual experimental runs.