M. Ferraro, F. Mangini, F. O. Wu, M. Zitelli, D. N. Christodoulides, S. Wabnitz
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However, it has been theoretically argued that the variables <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>T</mi></math> and <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>μ</mi></math> represent actual thermodynamic forces that control the exchange of the respective conjugate quantities between two subsystems. In this work, we report, for the first time, optical calorimetric measurements in nonlinear multimode fibers, which unambiguously demonstrate that both the temperature <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>T</mi></math> and the chemical potential <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>μ</mi></math> dictate the flow of their associated extensive quantities, i.e., the energy and the optical power. Specifically, we study the process of light thermalization associated with two orthogonally polarized laser beams. 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引用次数: 0
摘要
最近的研究表明,在非线性、高度多模系统中传播的光可以以完全类似于传统统计力学中遇到的方式热化。在热平衡状态下,系统的熵处于最大值,完全符合热力学第二定律。在这种情况下,一旦与这种光子气体相关的模式之间的统计功率分配达到雷利-让斯分布,熵就会达到极值,该分布完全由光学温度 T 和化学势 μ 来表征。然而,理论上有人认为,变量 T 和 μ 代表控制两个子系统之间各自共轭量交换的实际热动力。在这项工作中,我们首次报告了在非线性多模光纤中进行的光学量热测量,明确地证明了温度 T 和化学势 μ 都决定了其相关广泛量(即能量和光功率)的流动。具体来说,我们研究了与两束正交偏振激光束相关的光热化过程。我们的观测工作得益于最新开发的技术,这些技术允许我们在各种模式组内对光功率进行明智的多路复用/解复用。我们的研究结果表明,由于光子-光子碰撞,"热量 "只会从热光子气体子系统流向冷光子气体子系统--因此在这种全光热力学安排中,第二定律得到了明确的证明。除了基本原理之外,我们的发现还提供了一种利用热力学原理操纵激光束的新方法。
Calorimetry of Photon Gases in Nonlinear Multimode Optical Fibers
Recent studies have shown that light propagating in a nonlinear, highly multimode system can thermalize in a manner totally analogous to that encountered in traditional statistical mechanics. At thermal equilibrium, the system’s entropy is at a maximum, in full accord with the second law of thermodynamics. In such arrangements, the entropy is extremized once the statistical power allocation among modes associated with this photon gas attains a Rayleigh-Jeans distribution that is fully characterized by an optical temperature and a chemical potential . However, it has been theoretically argued that the variables and represent actual thermodynamic forces that control the exchange of the respective conjugate quantities between two subsystems. In this work, we report, for the first time, optical calorimetric measurements in nonlinear multimode fibers, which unambiguously demonstrate that both the temperature and the chemical potential dictate the flow of their associated extensive quantities, i.e., the energy and the optical power. Specifically, we study the process of light thermalization associated with two orthogonally polarized laser beams. Our observations are enabled by recently developed techniques that allow one to judiciously multiplex/demultiplex the optical power within various mode groups. Our results indicate that because of photon-photon collisions, “heat” only flows from a hot to a cold photon gas subsystem—thus providing an unequivocal demonstration of the second law in such all-optical thermodynamic arrangements. In addition to being fundamental, our findings provide a new approach to manipulate laser beams using thermodynamic principles.
期刊介绍:
Physical Review X (PRX) stands as an exclusively online, fully open-access journal, emphasizing innovation, quality, and enduring impact in the scientific content it disseminates. Devoted to showcasing a curated selection of papers from pure, applied, and interdisciplinary physics, PRX aims to feature work with the potential to shape current and future research while leaving a lasting and profound impact in their respective fields. Encompassing the entire spectrum of physics subject areas, PRX places a special focus on groundbreaking interdisciplinary research with broad-reaching influence.