Quantum Coherence Emerges as a Thermodynamic Fuel in Squeezed Reservoir Study

A theoretical study published in Quantum Information Processing examines how the loss of quantum coherence in a single qubit directly erodes its capacity to deliver usable work. The researchers, Maryam Hadipour, Hazhir Dolatkhah and Soroush Haseli, model a qubit coupled to a squeezed thermal reservoir within a pure dephasing framework, in which the system loses its quantum phase relationships without any exchange of energy. Because decoherence occurs in isolation from energy dissipation, the model offers an unusually clean setting for tracing the link between coherence and ergotropy, the portion of a system’s energy that can in principle be extracted as work.

Using exact dephasing dynamics, the team disentangles the coherent and incoherent contributions to ergotropy as the qubit evolves. Their calculations show that the decay of quantum coherence is accompanied by a reduction in extractable work, supporting the view that coherence functions as a genuine thermodynamic resource rather than a purely informational curiosity. In this dephasing-only setting, energy remains in the system while the quantum correlations that make part of that energy harvestable fade away.

The analysis identifies three reservoir characteristics that shape this process: temperature, spectral properties and squeezing parameters. According to the study, increasing the reservoir temperature and the squeezing strength both enhance decoherence and suppress ergotropy. This is a notable counterintuitive detail, since squeezing is often associated with quantum advantage; here, stronger squeezing of the thermal environment accelerates the degradation of the qubit’s work-extraction capability.

The picture changes in non-Markovian regimes, where the environment retains memory of the system. The results indicate that such regimes may partially preserve both coherence and the ability to extract work, suggesting that structured squeezed environments with memory effects could act as a brake on thermodynamic degradation. The authors present this as insight into the interplay between open-system dynamics and quantum thermodynamic resources.

As a theoretical investigation confined to a single qubit and a specific dephasing model, the work does not report experimental measurements or device performance. Its contribution lies in establishing, within an exactly solvable framework, a direct correspondence between coherence decay and ergotropy loss under controlled reservoir conditions. Translating these model results into laboratory or technological settings remains a task for subsequent experimental and theoretical work.

Subject of Research: Theoretical study of coherence-resolved ergotropy dynamics in a qubit coupled to a squeezed thermal reservoir

Article Title: Coherence-Resolved Ergotropy in a Qubit Coupled to a Squeezed Thermal Reservoir

Article References: Hadipour, M., Dolatkhah, H., & Haseli, S. (2026). Coherence-Resolved Ergotropy in a Qubit Coupled to a Squeezed Thermal Reservoir. Quantum Information Processing, 25(11), Article 349. https://doi.org/10.1007/s11128-026-05380-1

Image Credits: AI Generated

DOI: 10.1007/s11128-026-05380-1

Keywords: ergotropy, quantum coherence, qubit, squeezed thermal reservoir, pure dephasing, quantum thermodynamics, decoherence, non-Markovian dynamics, open quantum systems, extractable work, Coherence-Resolved, Coupled