



01563nas a2200169   4500008004100000245002700041210002700068260001400095300001200109490000700121520114400128100002201272700002401294700001801318700002001336856003701356       2020                        eng d00aDiscrete Time Crystals0 aDiscrete Time Crystals  c3/10/2020  a467-4990 v113 a<p><span style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, &quot;Lucida Grande&quot;, &quot;Helvetica Neue&quot;, Helvetica, Arial, sans-serif; font-size: 14px;">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 &quot;discrete time crystals&quot;, 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.&nbsp;</span></p>1 aElse, Dominic, V.1 aMonroe, Christopher1 aNayak, Chetan1 aYao, Norman, Y.  uhttps://arxiv.org/abs/1905.13232