Zentrum für Optische Quantentechnologien and Institut für Laser-Physik, Universität Hamburg, 22761 Hamburg, Germany.
The Hamburg Center for Ultrafast Imaging, 22761 Hamburg, Germany.
Science. 2022 Aug 5;377(6606):670-673. doi: 10.1126/science.abo3382. Epub 2022 Jun 9.
Time crystals are classified as discrete or continuous depending on whether they spontaneously break discrete or continuous time translation symmetry. Although discrete time crystals have been extensively studied in periodically driven systems, the experimental realization of a continuous time crystal is still pending. We report the observation of a limit cycle phase in a continuously pumped dissipative atom-cavity system that is characterized by emergent oscillations in the intracavity photon number. The phase of the oscillation was found to be random for different realizations, and hence, this dynamical many-body state breaks continuous time translation symmetry spontaneously. Furthermore, the observed limit cycles are robust against temporal perturbations and therefore demonstrate the realization of a continuous time crystal.
时间晶体根据其是否自发打破离散或连续的时间平移对称性而被分类为离散或连续。尽管在周期性驱动系统中已经广泛研究了离散时间晶体，但连续时间晶体的实验实现仍有待完成。我们报告了在连续泵送耗散原子腔系统中观察到的极限环相，其特征是腔内光子数出现突发的振荡。发现不同实现的振荡相位是随机的，因此，这种动力学多体状态自发地打破了连续时间平移对称性。此外，观察到的极限环对时间扰动具有鲁棒性，因此证明了连续时间晶体的实现。
