The Andrew & Erna Viterbi Faculty of Electrical Engineering, Technion, 32000, Haifa, Israel.
Nat Commun. 2019 Feb 14;10(1):747. doi: 10.1038/s41467-019-08527-0.
Bose-Einstein condensation (BEC) is a special many-boson phenomenon that was observed in atomic particles at ultra-low temperatures. Later, BEC was also shown for non-atomic bosons, such as photons. Those experiments were usually done in micron-size cavities, where the power (particle number) was varied, and not the temperature, until condensation was reached. Here we demonstrate BEC of photons in a few-meters-long one-dimensional (1D) erbium-ytterbium co-doped fiber cavity at, below and above room temperature, between 100 K and 415 K. The experiments were done at about the 1550 nm wavelength regime having a few to tens of μW intra-cavity light power (10-10 photons). By varying the power and also the temperature, we found linear dependence of the condensation on power for various temperatures and of the critical power (for condensation) on temperature. These findings agree, functionally and quantitatively, with the theoretical BEC prediction without any adjustable parameter.
玻色-爱因斯坦凝聚（BEC）是一种特殊的多玻色子现象，最初在超低温下的原子粒子中被观察到。后来，BEC 也在非原子玻色子中被展示出来，例如光子。这些实验通常在微米级的腔中进行，通过改变功率（粒子数）而不是温度来实现凝聚。在这里，我们在室温以下和以上的 100 K 到 415 K 范围内，在几米长的掺铒-掺镱光纤腔中演示了几到几十微瓦腔内光功率（10-10 个光子）的光子 BEC。实验是在大约 1550nm 波长范围内进行的。通过改变功率和温度，我们发现了在不同温度下凝聚对功率的线性依赖性，以及在临界功率（凝聚）对温度的依赖性。这些发现与理论 BEC 预测在功能和数量上一致，没有任何可调参数。
