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Emergence of continuous rotational symmetries in ultracold atoms coupled to optical cavities

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Chiacchio, EIR 
Nunnenkamp, Andreas  ORCID logo  https://orcid.org/0000-0003-2390-7636

Abstract

We investigate the physics of a gas of ultracold atoms coupled to three single-mode optical cavities and transversely pumped with a laser. Recent work has demonstrated that, for two cavities, the Z2 symmetries of each cavity can be combined into a global U(1) symmetry. Here, we show that when adding an extra cavity mode, the low-energy description of this system can additionally exhibit an SO(3) rotational symmetry which can be spontaneously broken. This leads to a superradiant phase transition in all the cavities simultaneously, and the appearance of Goldstone and amplitude modes in the excitation spectrum. We determine the phase diagram of the system, which shows the emergence and breaking of the continuous symmetries and displays first- and second-order phase transitions. We also obtain the excitation spectrum for each phase and discuss the atomic self-organized structures that emerge in the different superradiant phases. We argue that coupling the atoms equally to n different modes will in general generate a global SO(n) symmetry if the mode frequencies can be tuned to the same value.

Description

Keywords

cond-mat.quant-gas, cond-mat.quant-gas

Journal Title

Physical Review A

Conference Name

Journal ISSN

2469-9926
2469-9934

Volume Title

98

Publisher

American Physical Society (APS)
Sponsorship
The Royal Society (uf130303)
Engineering and Physical Sciences Research Council (EP/N509620/1)