The first time that a time crystal breaks continuous time translation symmetry has been achieved by researchers at the Institute of Laser Physics, Universitat Hamburg. Their observation was published in Science online on Thursday, 9th June 2022.

Franck Wilczek (Nobel laureate) first suggested the idea of a "time crystal". The formation of a time crystal causes the system's time translation symmetry to spontaneously break. This is similar to water turning spontaneously into ice at the freezing point and breaking its translation symmetry.

Researchers have observed discrete time crystals, or Floquet times crystals, in periodically driven closed and opened quantum systems. Dr. Hans Kessler, from Prof. Andreas Hemmerich’s Cluster of Excellence CUI: Advanced Imaging of Matter, says that "in all previous experiments however, the continuous time translation symmetry was broken by a Floquet time drive." "The challenge was to create a system that breaks the continuous-time translation symmetry spontaneously.

Using a Bose-Einstein condensate inside an optical high-finesse cavity

The scientists used an optical high-finesse cavities to condense the Bose-Einstein condensate. They observed a limit phase that was characterized by periodic oscillations in the intracavity number and atomic density cycling through recurring patterns using a time-independent pump.

The time phase of oscillations took random values between 0 to 2p as expected for spontaneously broken continuoussymmetry. Researchers demonstrated the robustness and stability of the dynamic phase by identifying the stability zone in the relevant parameter space.