发表机构
Instituto de Física, Universidade Federal de Goiás; Department of Physics, Zhejiang Normal University; Department of Fundamental Sciences, Hainan Bielefeld University of Applied Sciences（戈亚斯联邦大学物理研究所; 浙江师范大学物理学院; 海南比勒费尔德应用科学大学基础科学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究粒子数反转和集体弛豫对Dicke奥托机性能的增强机制，发现反转使功和可靠性线性增长，而集体耦合加速动力学，且增强输出源于消耗活性态资源。
AI 中文摘要
粒子数反转和集体弛豫都能提升量子热机的性能，但通过不同的机制实现。我们研究了一种量子奥托机，其工作介质是由$N$个二能级组分构成的对称集体自旋。对于对易的做功冲程和集体库耦合，动力学精确约化为Dicke阶梯上的有限生灭过程，从而能够统一处理稳态运行、功涨落和有限时间弛豫。在完全重置极限下，每个循环的无源功随系统尺寸饱和，而粒子数反转产生的功随$N$线性增长。功可靠性表现出相同的线性标度，超过了$N$个独立引擎的平方根行为。这种增强源于热态和冷态之间的宏观极化位移，而集体耦合则通过Dicke跃迁速率加速有限时间动力学。对于匹配的无源和反转热态，额外总功等于奥托效率乘以反转态的ergotropy。为相应的可逆多余态形成成本充电会消除这一优势，表明增强的输出转化了预先存在的活性态资源，而非产生免费的热力学增益。精确的有限接触轨迹统计进一步量化了在远离完全重置时，集体动力学、涨落、关联和资源核算如何保持联系。
英文摘要
Population inversion and collective relaxation can both enhance the performance of a quantum heat engine, but through distinct mechanisms. We study a quantum Otto engine whose working medium is a symmetric collective spin of $N$ two-level constituents. For commuting work strokes and collective reservoir coupling, the dynamics reduces exactly to a finite birth--death process on the Dicke ladder, allowing a unified treatment of stationary operation, work fluctuations, and finite-time relaxation. In the complete-reset limit, passive work per cycle saturates with system size, whereas population inversion yields work that grows linearly with $N$. The work reliability shows the same linear scaling, exceeding the square-root behavior of $N$ independent engines. This enhancement originates from a macroscopic polarization displacement between hot and cold states, while collective coupling instead accelerates the finite-time dynamics through Dicke transition rates. For matched passive and inverted hot states, the extra gross work equals the Otto efficiency times the ergotropy of the inverted state. Charging the corresponding reversible excess state-formation cost removes this advantage, showing that the enhanced output converts a pre-existing active-state resource rather than generating a free thermodynamic gain. Exact finite-contact trajectory statistics further quantify how collective kinetics, fluctuations, correlations, and resource accounting remain linked away from complete reset.
