Crystallized time in ultra-cold Bose gases

Abstract

Discrete time crystals can be created within a Bose-Einstein condensate by modulating its trapping potential such that a breathing mode in the radial direction emerges. This mode drives a higher order axial mode at twice the driving period, breaking discrete time symmetry. Here sodium-23 atoms are used to create the Bose-Einstein condensate and holographic imaging is used to take up to 100 pictures of it, allowing for observation of its emergent modes in time. We resolve the growth of the time crystal and investigate it for different condensation fractions. Numerov's algorithm is employed to numerically investigate the possibility of tunneling between two different phases of the time crystalline state. This work can be used as a basis for further research into time crystals created in a cloud of ultra-cold atoms.