TY - JOUR T1 - Discrete Time Crystals JF - Annual Review of Condensed Matter Physics Y1 - 2020 A1 - Dominic V. Else A1 - Christopher Monroe A1 - Chetan Nayak A1 - Norman Y. Yao AB -

Experimental advances have allowed for the exploration of nearly isolated quantum many-body systems whose coupling to an external bath is very weak. A particularly interesting class of such systems is those which do not thermalize under their own isolated quantum dynamics. In this review, we highlight the possibility for such systems to exhibit new non-equilibrium phases of matter. In particular, we focus on "discrete time crystals", which are many-body phases of matter characterized by a spontaneously broken discrete time translation symmetry. We give a definition of discrete time crystals from several points of view, emphasizing that they are a non-equilibrium phenomenon, which is stabilized by many-body interactions, with no analog in non-interacting systems. We explain the theory behind several proposed models of discrete time crystals, and compare a number of recent realizations, in different experimental contexts. 

VL - 11 U4 - 467-499 UR - https://arxiv.org/abs/1905.13232 U5 - https://doi.org/10.1146/annurev-conmatphys-031119-050658 ER -