Realization of a time-crystal in a dc-driven atom-cavity system

• Applicant: Dr. Hans Keßler
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426796523

The central objective of this proposal is to experimentally realize a dc driven time-crystal using an atom-cavity system comprising a Bose-Einstein condensate (BEC) strongly coupled to a high-finesse low-bandwidth optical cavity. To this end, I propose to employ the so far experimentally unexplored regime of pump light, which is blue detuned with respect to the relevant atomic resonances. Theoretical preparatory work indicates excellent chances that this endeavour should succeed. The mean-field and truncated Wigner simulations presented in the project description predict a rich phase diagram with four distinct many-body states: a homogenous BEC phase, a density wave phase, a time-crystal phase and a chaotic phase. Above a critical pump strength, the atomic sample forms a self-organized Bragg grating referred to as density wave phase. This phase becomes unstable above a second threshold value of the pump strength. The resulting non-equilibrium state of matter breaks the time-translation symmetry and realizes the concept of a time-crystal. All so far realized time-crystals break a discrete time-translation symmetry and are therefore called Floquet time-crystals. A notable novelty of this project is the creation of a time-crystal that breaks a continuous time-translation symmetry, such that a more stringent analogy to the concept of spatial crystals holds.

• DFG Programme: Research Grants
• International Connection: Brazil
• Co-Investigators: Professor Dr. Jayson G. Cosme; Professor Dr. Andreas Hemmerich; Professor Dr. Ludwig Mathey
• Cooperation Partner: Professor Dr. Vanderlei Salvador Bagnato