Speaker
Description
Quantum thermodynamics asks whether the laws of thermodynamics are modified, enriched, or fundamentally constrained by quantum mechanics. A central question is whether uniquely quantum features — such as coherence, superposition, and noncommutativity — can provide thermodynamic advantages over classical systems, or whether such advantages ultimately admit classical explanations.
This work investigates the role of equilibrium quantum coherence in the performance of a quasistatic quantum heat engine. We study a quasistatic quantum Otto cycle with a two-mode Bose–Einstein condensate as the working medium, whose Hamiltonian contains noncommuting terms that generate equilibrium coherence in a reference basis defined by the noninteracting limit. Without interactions, this coherence is thermodynamically inactive: the cycle efficiency depends only on the energy scales at the hot and cold points. Introducing interactions changes this picture. The efficiency departs from the noninteracting baseline, and the work naturally separates into contributions from thermal populations and equilibrium coherence. The coherence-driven contribution arises solely from the noncommuting interaction term and is closely tracked by a cycle coherence measure based on the relative entropy of coherence.
To assess whether this effect is genuinely quantum, we construct a classical analogue using an anisotropic classical spin with the corresponding classical Hamiltonian. Perturbative analysis and numerical simulations show that the classical and quantum work agree up to corrections arising from the finite level spacing of the quantum spectrum, converging in the large-spin semiclassical limit. These results show that equilibrium coherence admits a classical counterpart, suggesting that future work should investigate whether the effects of finite-time driving and dynamical coherence also admit a classical explanation.
| I am the presenting author | Yes |
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