Observation of discrete time-crystalline order in a disordered dipolar many-body system

Discrete time-crystalline order is observed in a driven, disordered ensemble of about one million dipolar spin impurities in diamond at room temperature, and is shown to be very stable to perturbations. Time crystals aren't forever Much like ordinary crystals, time crystals exhibit a high degree of structural order. But whereas ordinary crystals get their periodicity from the regular repetition of spatial elements, time crystals are an exotic, non-equilibrium state of matter in which the same structures repeat themselves in time. Predicted to exist a few years ago, time crystals have so far resisted experimental demonstration. Now, two groups offer evidence for experimental observation of this elusive form of matter. Jiehang Zhang et al . create a specific kind of time crystal—a discrete time crystal—in a chain of ten trapped ions under the influence of periodic driving. Mikhail Lukin and colleagues achieve a similar feat using approximately one million nitrogen–vacancy spin impurities in diamond as an experimental platform. In both cases, the time-crystalline order is shown to be robust to external perturbations. Such time crystals could potentially find applications in robust quantum memory. Understanding quantum dynamics away from equilibrium is an outstanding challenge in the modern physical sciences. Out-of-equilibrium systems can display a rich variety of phenomena, including self-organized synchronization and dynamical phase transitions 1 , 2 . More recently, advances in the controlled manipulation of isolated many-body systems have enabled detailed studies of non-equilibrium phases in strongly interacting quantum matter 3 , 4 , 5 , 6 ; for example, the interplay between periodic driving, disorder and strong interactions has been predicted to result in exotic ‘time-crystalline’ phases 7 , in which a system exhibits temporal correlations at integer multiples of the fundamental driving period, breaking the discrete time-translational symmetry of the underlying drive 8 , 9 , 10 , 11 , 12 . Here we report the experimental observation of such discrete time-crystalline order in a driven, disordered ensemble of about one million dipolar spin impurities in diamond at room temperature 13 , 14 , 15 . We observe long-lived temporal correlations, experimentally identify the phase boundary and find that the temporal order is protected by strong interactions. This order is remarkably stable to perturbations, even in the presence of slow thermalization 16 , 17 . O