AI 中文总结
该研究分析含非互易材料的封闭圆柱构型中电磁涨落引发的热传递与扭矩关系，推导相关表达式与解析公式，验证热机效率受卡诺极限约束。
AI 中文摘要
电磁涨落不仅能传递能量，还能传递角动量，在非平衡体系中引发力、扭矩、热流和摩擦。在封闭构型中，我们证明若两个物体中至少一个具有旋转对称性，扭矩会受热传递约束，因为二者均源自携带角动量$\boldsymbol{\bar{h}n}$和能量$\boldsymbol{\bar{h}ω}$的光子传递。仅假设一个物体具有旋转对称性时，互易介质也可能产生非零扭矩；但当两个物体都具有旋转对称性时，需要非互易介质打破$n$与$-n$之间的对称性才能产生非零扭矩。随后我们聚焦于具有非互易介电响应的同心圆柱，利用Rytov涨落电动力学，将热传递和扭矩表示为角动量分辨通量密度$Φ_n(ω)$的函数。我们还采用邻近力近似分析了内圆柱稳定悬浮的条件，在此过程中得到了不同温度下稀薄平板间法向Casimir力的新解析公式。最后，为求解无接触发动机构型中的输出功，我们计算了内圆柱缓慢旋转时的涨落诱导摩擦，并得到了扭矩、摩擦与热传递之间的约束关系。受该约束限制，热机的效率仍受卡诺极限约束。
英文摘要
Electromagnetic fluctuations can transfer not only energy but also angular momentum, leading to forces, torques, heat currents, and friction in out-of-equilibrium setups. In enclosing configurations, we show that if at least one of two objects is rotationally symmetric, the torque is bounded by heat transfer, since both arise from photon transfers with angular momentum $\hbar n$ and energy $\hbarω$. With only one object assumed to be rotationally symmetric, it may be possible to obtain a nonzero torque with reciprocal media, but nonreciprocal media are required to break the symmetry between $n$ and $-n$ and produce a nonzero torque if both objects are rotationally symmetric. We then specialize to concentric cylinders with a nonreciprocal dielectric response and use Rytov fluctuational electrodynamics to express heat transfer and torque in terms of an angular-momentum-resolved flux density, $Φ_n(ω)$. We also analyze the conditions for stable levitation of the inner cylinder using the proximity force approximation, in the process obtaining a new analytic formula for the normal Casimir force between dilute plates at different temperatures. Finally, to find the extracted work in a contactless engine setup, we compute the fluctuation-induced friction for a slowly rotating inner cylinder, and we find a bound between torque, friction, and heat transfer. Due to this bound, the efficiency of the heat engine remains bounded by the Carnot limit.
Comments19 pages, 7 figures
