Seeding Crystallization in Time

We introduce the concept of seeding of crystallization in time by studying the dynamics of an ensemble of coupled continuous time crystals. We demonstrate that a single subsystem in the broken-symmetry phase acting as a nucleation center may induce time-translation symmetry breaking across the entire ensemble. The seeding effect is observed for both coherent as well as dissipative coupling, and for a broad range of parameter regimes. In the spirit of mutual synchronization, we investigate the dynamics where all subsystems are in the broken symmetry phase. We observe that more broadly detuned time crystals require weaker coupling strength in order for synchronization to occur. This is in contrast to basic knowledge from classical as well as quantum synchronization theory. We show that this surprising observation is a direct consequence of the seeding effect.