Realizing Discrete Time Crystals in Quantum Dot Spin Arrays with Magnetic Field Gradients

A discrete time crystal is a non-equilibrium phase of matter that arises from a combination of interactions, disorder, and periodic driving. Previous work showed that it is possible to realize this phase in quantum dot spin arrays with nearest-neighbor exchange interactions if the number of pulses per period is substantially increased. Here, we show that the same result can be achieved using a magnetic field gradient instead of additional pulses, significantly reducing the demands on experimental capabilities. Numerical simulations of the return probability and mutual information confirm the time crystalline structure, which survives over a broad range of parameters and perturbations. In addition, we derive a stroboscopic effective Hamiltonian that provides further insight into the nature of this phase and the quantum state preservation properties it features.