Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany.
Phys Rev Lett. 2023 Jan 20;130(3):033602. doi: 10.1103/PhysRevLett.130.033602.
For equilibrium systems, the magnitude of thermal fluctuations is closely linked to the dissipative response to external perturbations. This fluctuation-dissipation relation has been described for material particles in a wide range of fields. Here, we experimentally probe the relation between the number fluctuations and the response function for a Bose-Einstein condensate of photons coupled to a dye reservoir, demonstrating the fluctuation-dissipation relation for a quantum gas of light. The observed agreement of the scale factor with the environment temperature both directly confirms the thermal nature of the optical condensate and demonstrates the validity of the fluctuation-dissipation theorem for a Bose-Einstein condensate.
对于平衡系统，热涨落的大小与对外部扰动的耗散响应密切相关。这种涨落耗散关系已在广泛的领域中被描述为物质粒子的关系。在这里，我们通过实验探测了与染料库耦合的光子玻色-爱因斯坦凝聚体的数涨落与响应函数之间的关系，证明了光量子气体的涨落耗散关系。观察到的比例因子与环境温度的一致性，既直接证实了光学凝聚体的热性质，又证明了玻色-爱因斯坦凝聚体的涨落耗散定理的有效性。
