Realizing time crystals in discrete quantum few-body systems

The exotic phenomenon of time-translation-symmetry breaking under periodic driving—one of the main features of the so-called time crystals—has been shown to occur in many-body systems even in clean setups where disorder is absent. In this work, we propose a realization of this effect in few-body systems, both in the context of trapped cold atoms with strong interactions and of a circuit of superconducting qubits. We show how these two models can be treated in a fairly similar way by adopting an effective spin-chain description, to which we apply a simple driving protocol. We focus on the response of the magnetization in the presence of imperfect pulses and interactions, and show how the results can be interpreted, in the cold atomic case, in the context of experiments with trapped bosons and fermions. Furthermore, we provide a set of realistic parameters for the implementation of the superconducting circuit