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Advanced Quantum Technologies

Quantum Otto Engine With Coherence in Cavity Quantum Electrodynamics

Zuan Meng, Xin‐Ru Fang, Jingyu Zhang, Liu‐Yong Cheng, Xue Yan Han, Hong‐Fu Wang, Shou Zhang

Published Oct 24, 2025• 2 citations
Publisher

Abstract

Abstract A scheme is theoretically proposed to investigate a quantum Otto engine (QOE) based on cavity quantum electrodynamics (QED) systems, where the working substance consists of a single‐mode optical cavity coupled to either one or two identical two‐level atoms, corresponding to the Jaynes–Cummings (JC) and Tavis–Cummings (TC) models, respectively. These results show that quantum coherence can enhance the efficiency of the quantum Otto heat engine (QOHE) and that the QOE can operate in various thermodynamic modes, such as a heat engine, refrigerator, or heater. Building on these two cavity QED models, it is further demonstrated that increasing the number of atoms leads to an exponential enhancement in the work output of the QOHE. Finally, a localized quantum engine is analyzed by tracing out one of the atoms in the TC model and show that the local system can achieve an efficiency comparable to that of the global system. This work establishes a novel theoretical framework for understanding and optimizing the performance of quantum heat engines in cavity QED platforms.

DOI
10.1002/qute.202500516

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Communications in Theoretical Physics•Aug 14, 2025•1 citation
Abstract A scheme is theoretically proposed to investigate a quantum Otto engine (QOE) based on cavity quantum electrodynamics (QED) systems, where the working substance consists of a single‐mode optical cavity coupled to either one or two identical two‐level atoms, corresponding to the Jaynes–Cummings (JC) and Tavis–Cummings (TC) models, respectively. These results show that quantum coherence can enhance the efficiency of the quantum Otto heat engine (QOHE) and that the QOE can operate in various thermodynamic modes, such as a heat engine, refrigerator, or heater. Building on these two cavity QED models, it is further demonstrated that increasing the number of atoms leads to an exponential enhancement in the work output of the QOHE. Finally, a localized quantum engine is analyzed by tracing out one of the atoms in the TC model and show that the local system can achieve an efficiency comparable to that of the global system. This work establishes a novel theoretical framework for understanding and optimizing the performance of quantum heat engines in cavity QED platforms.
The simple system of two two-level identical atoms couple to single-mode optical cavity in the resonance case is studied for investigating the thermal entanglement. It is interesting to see that the critical temperature is only dependent on the coefficient of atom-atom dipole-dipole interaction. Based on the mode, we construct and investigate a entangled quantum Otto engine (QOE). Expressions for several important performance parameters such as the heat transferred, the work done in a cycle, and the efficiency of the entangled QOE in zero G are derived in terms of thermal concurrence. Some intriguing features and their qualitative explanations are given. Furthermore, the validity of the second law of thermodynamics is confirmed in the entangled QOE. The results obtained here have general significance and will be helpful to understand deeply the performance of an entangled QOE.
We study a quantum heat engine (QHE) with a working medium described by a parity-deformed Jaynes–Cummings (JC) model consisting of two identical two-level atoms interacting with a single-mode para-Bose field in a cavity. Compared to the standard two-atom JC model, this model introduces the action of a specific local classical field as an external control. This QHE operates under a quantum Otto cycle, where the working substance interacts with two reservoirs at different temperatures through four stages including two quantum isochoric processes and two quantum adiabatic processes. We investigate influence of the local external classical fields on the positive work condition as well as the efficiency of the engine, with emphasis on the control role of the local external classical fields. In the absence of local classical fields, we analytically show that work can not be extracted at low-temperature reservoirs, while a remarkable work is extracted for any temperature under the local classical fields. Meanwhile, we show that the efficiency of our engine reaches the classical Carnot value in the low-temperature regime. We also study the thermal atom-atom entanglement at the end of isochoric stages and show that it will be maintained by adjusting the intensity of the local classical fields. Interestingly, we find that the reduction of the thermal atom-atom entanglement during the cold bath stage acts as a resource for positive work extraction.
Quantum heat engines (QHEs) are established by applying the principles of quantum thermodynamics to small-scale systems, which leverage quantum effects to gain certain advantages. In this study, we investigate the quantum Otto cycle by employing the dipole-dipole coupled polar molecules as the working substance of QHE. Here, the molecules are considered to be trapped within an optical lattice and located in an external electric field. We analyze the work output and the efficiency of the quantum Otto heat engine (QOHE) as a function of various physical parameters, including electric field strength, dipole-dipole interaction and temperatures of heat baths. It is found that by adjusting these physical parameters the performance of the QOHE can be optimized effectively. Moreover, we also examine the influences of the entanglement and relative entropy of coherence for the polar molecules in thermal equilibrium states on the QOHE. Our results demonstrate the potential of polar molecules in achieving QHEs.
We investigate a quantum Otto engine (QOE) constructed from the two-qubit quantum Rabi model, operating within a cavity quantum electrodynamics (QED) architecture. The engine operates with two qubits as the working substance and a single non-Markovian hot thermal bath, modeled via the hierarchical equations of motion (HEOM) formalism. In place of a conventional cold thermal reservoir, the cooling stroke is realized through a projective measurement protocol on the cavity mode, which acts as an ancillary subsystem and effectively mimics a cold bath for the qubit working medium via measurement back-action. A squeezing drive applied to the cavity mode serves as a quantum fuel. We demonstrate that cavity squeezing systematically enhances both the power output and operational efficiency of the engine - the work extracted per unit of heat drawn from the hot bath-driving it above the standard quantum Otto limit. In the limit-cycle regime, the efficiency, while remaining above the Otto bound throughout, asymptotically converges to it from above. This identifies squeezing as a controllable quantum resource for thermodynamic optimization. Our results reveal that the interplay between qubit-cavity coupling, measurement-induced cooling, and non-equilibrium squeezing gives rise to a multi-resource thermodynamic architecture with performance characteristics inaccessible to conventional two-bath quantum Otto engines, thereby providing a concrete route toward experimentally realizable quantum heat engines in cavity QED platforms.
Abstract We propose a quantum Otto heat engine using a finite-size Dicke-Stark model as the working substance. In the extended coherent state space, the complete energy spectrum and eigenstates are obtained through numerical calculations. Within the infinite-time and finite-time thermodynamics frameworks, we find that the output work, efficiency, and power can be optimized by adjusting the Stark field strength, the qubit–boson coupling strength, stroke times, and number of atoms. Our results reveal that output work and efficiency are maximized near the coupling strength at the superradiant phase transition (SPT). Tuning the Stark field strength modifies the energy level structure and SPT, effectively suppressing entropy generation and quantum friction during nonequilibrium evolution. We also show that asymmetric heat engines—where the two isochoric strokes operate with different Stark field strengths and durations—further improve engine performance. These results may guide future implementations of efficient quantum heat engines.
Abstract We developed a model of a quantum Otto engine using two coupled two-level atoms. Based on the platform, we show that frequency detuning and the coupling strength induced by dipole-dipole interactions can lead to decoherence by disrupting coherent energy exchange. We focus on fundamental thermodynamic quantities, including heat absorption, release to heat baths, work done and efficiency. It is noteworthy that the interatomic coupling strength and frequency detuning do not merely affect the shape of the work and the efficiency but ultimately govern its quantitative magnitude. In the field of quantum thermodynamics, we have established an upper bound efficiency that is stricter than the Carnot limit. Moreover, our analysis confirms that quantum coherence enables the system to exceed the efficiency threshold of a classical Otto heat engine. The second law of thermodynamics holds all the while. Our results constitute a step forward in the design of conceptually new quantum thermodynamic devices which take advantage of uniquely quantum resources of quantum coherence.