Boundary time crystals
Fernando Iemini (Universidade Federal Fluminense)
Spontaneous symmetry breaking is a cornerstone of physics and occurs at all energy scales, in cosmology and high-energy physics as well as in condensed matter. Breaking space translation symmetry for example gives rise to crystals, while superfluids and ferromagnets are manifestations or the spontaneous breaking of gauge or rotational invariance, respectively. Amongst all possible complex situations that were considered and experimentally verified so far breaking the time-translation symmetry, generating a « time-crystal », had not received attention. The possible existence of time crystals, first addressed by Wilczek in 2013, prompted an intense discussion.
In this seminar we will discuss about this new phase of matter, and present our recent results predicting a novel form of time-translation symmetry breaking: continuous Boundary Time Crystals (BTCs). In the BTC phase, symmetry breaking appears in a (macroscopic) fraction of the system. Moreover, a BTC breaks the continuous time-translation symmetry, i.e. the system self-organises in a time periodic pattern with a period which only depends on its coupling constants.