  The control of many-body quantum dynamics in complex systems is a key
challenge in the quest to reliably produce and manipulate large-scale quantum
entangled states. Recently, quench experiments in Rydberg atom arrays
(Bluvstein et. al., arXiv:2012.12276) demonstrated that coherent revivals
associated with quantum many-body scars can be stabilized by periodic driving,
generating stable subharmonic responses over a wide parameter regime. We
analyze a simple, related model where these phenomena originate from
spatiotemporal ordering in an effective Floquet unitary, corresponding to
discrete time-crystalline (DTC) behavior in a prethermal regime. Unlike
conventional DTC, the subharmonic response exists only for Neel-like initial
states, associated with quantum scars. We predict robustness to perturbations
and identify emergent timescales that could be observed in future experiments.
Our results suggest a route to controlling entanglement in interacting quantum
systems by combining periodic driving with many-body scars.
