  A discrete time crystal is a recently discovered non-equilibrium phase of
matter that has been shown to exist in disordered, periodically driven Ising
spin chains. In this phase, if the system is initially prepared in one of a
certain class of pure multispin product states, it periodically returns to this
state over very long time scales despite the presence of interactions,
disorder, and pulse imperfections. Here, we show that this phase occurs in GaAs
quantum dot spin arrays containing as few as three quantum dots, each confining
one electron spin, for naturally occurring levels of nuclear spin noise and
charge noise. Although the physical interaction in these arrays is a
nearest-neighbor Heisenberg exchange interaction, we show that this can be
effectively converted into an Ising interaction by applying additional pulses
during each drive period. We show that by changing the rotation axis of these
pulses, we can select the direction of the Ising interaction and, consequently,
the quantization axis of the stabilized multispin states. Moreover, we
demonstrate that it is possible to perform coherent rotations of the stabilized
states while remaining in the time crystal phase. These findings open up the
intriguing possibility of using time crystal phases to extend the lifetime of
quantum states for information applications.
