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中国物理学会期刊

非对易耦合自旋的量子热输运与量子热器件效应的研究

Quantum heat transport and effects of quantum thermal devices in noncommuting coupled spins

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  • 量子热输运是研究非平衡量子体系中能量交换微观过程与统计规律的一个重要问题.本文研究了非对易耦合自旋体系在有限温差驱动下的稳恒态热输运特性.基于开放量子体系理论,采用量子缀饰态主方程系统分析了热流在不同自旋耦合强度与自旋数目下的行为.研究结果表明,非对易自旋耦合能够显著调控量子体系热输运的非线性特征.在弱自旋耦合区间内,不同自旋数目均出现负微分热导行为.解析发现在单自旋与大自旋极限下,热流均由微观循环流主导,解释了负微分热导与热整流出现的微观机制.同时,耦合自旋体系在自旋强耦合与大温差条件下,由于热流出现单向饱和性,也能呈现显著的热整流效应.进一步通过优化调控系统参数,可实现三端口体系中的量子热放大器件效应.希望本文的研究结果可以为量子热器件的设计与优化提供理论依据.

    Quantum heat transport governs the energy exchange processes and statistical laws in non-equilibrium quantum systems, and also plays a pivotal role in the advance of quantum thermodynamics. In this work, we comprehensively investigate steady-state thermal transport properties of a noncommuting coupled spin system driven by a finite temperature bias. The system comprises interacting spin ensembles separately coupled to independent bosonic thermal reservoirs. We employ the quantum dressed master equation approach within the framework of open quantum system theory to properly analyze the non-equilibrium dynamics, ensuring the validity of the transport results in the strong coupling regime. Our results demonstrate that the noncommuting spin coupling serves as a significant resource for modulating nonlinearities of the heat current. Specifically, in the weak spin-coupling regime, the system exhibits a robust negative differential thermal conductance (NDTC) phenomenon across various spin numbers. By deriving analytical expressions of the heat current in both single-spin and large-spin limits, we reveal that this NDTC behavior is dominated by microscopic cycle fluxes. Physically, this arises because the spin excitation channels induced by the cold reservoir are suppressed under the large temperature bias, thereby blocking the energy exchange cycles. Conversely, in the strong spin-coupling and large temperature bias regime, the quantum system demonstrates a significant thermal rectification effect. This high rectification effciency originates from the unidirectional saturation of the heat current, making the system a promising candidate for high-performance thermal diodes. Furthermore, we extend the model to a three-terminal configuration to construct a quantum thermal transistor. By manipulating the temperature of the gate reservoir, we achieve effcient modulation and amplification of the heat flow between the source and the drain. It is shown that the heat amplification factor βR can far exceed unity in specific operating regions, confirming the realization of significant thermal amplification. These findings not only elucidate the rich nonlinear transport phenomena induced by noncommuting interactions, but also provide a theoretical basis for designing controllable quantum thermal logic devices, such as thermal rectifiers and transistors.

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