Quantum thermodynamics with uncertain equilibrium

2026-04-15

AI Summary

This work addresses a fundamental limitation in conventional quantum thermodynamics, which assumes perfect knowledge of thermal equilibrium states—an idealization undermined by realistic uncertainties in the system Hamiltonian and bath temperature. To account for such equilibrium uncertainty, the authors develop a generalized quantum thermodynamic framework incorporating “clean” and “dirty” battery models. Leveraging resource theory and min-/max-relative entropies constrained to subspaces, they rigorously characterize thermodynamic transformations in both single-shot and asymptotic regimes. Their analysis reveals an intrinsic limitation on purifying nonequilibrium states: even infinitesimal uncertainty induces strong thermodynamic irreversibility, analogous to bound entanglement. Moreover, while the clean model permits state formation but forbids work extraction, the dirty model exhibits the opposite behavior, demonstrating that equilibrium uncertainty fundamentally reshapes thermodynamic limits.

Technology Category

• Machine Learning: Calibration & Uncertainty Quantification
• Reasoning under Uncertainty: Uncertainty Representations
• Game Theory and Economic Paradigms: Equilibrium

Application Category

• Web Mining and Content Analysis: Models for Web evolution
• Security and Privacy: Large-scale security measurements
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs

Abstract

The resource-theoretic approach to quantum thermodynamics assumes complete knowledge of the thermal equilibrium against which thermodynamic resources are defined. In practice, however, this state is determined by the system Hamiltonian and the bath temperature, neither of which is known with perfect precision. We develop a framework in which the equilibrium reference is specified by a set of candidate states reflecting this uncertainty. Under a generic geometric condition, we prove a no-go theorem that sharply limits athermality ``purification'': conversion from an uncertain athermality resource to a definite target is either trivial or impossible, with no room for tradeoff. We then introduce two complementary battery models: a clean battery with a precisely known equilibrium state and a dirty battery with an uncertain one. For both models, we derive exact one-shot entropic characterizations of work extraction and work of formation in terms of standard min- and max-relative entropies and new subspace-constrained variants. In the asymptotic regime, both models exhibit a strong form of thermodynamic irreversibility. In particular, we give a simple and explicit example in which, in the clean-battery model, work is required to form a state but no work can be extracted from it, in direct analogy with bound entanglement, whereas in the dirty-battery model, work can be extracted but formation requires infinite work cost. These phenomena persist even under arbitrarily small uncertainty, showing that equilibrium uncertainty is not a minor perturbation of the standard theory but a qualitatively new ingredient that reshapes the fundamental limits of thermodynamic resource interconversion.

Problem

• quantum thermodynamics
• uncertain equilibrium
• athermality
• thermodynamic irreversibility
• resource theory

Innovation

• quantum thermodynamics
• equilibrium uncertainty
• athermality purification
• thermodynamic irreversibility
• resource theory