Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom

Doping semiconductor quantum dots with transition elements can create an optical probe and can control spins of individual magnetic atoms. Such atoms that feature both spin and orbital degrees of freedom present a large spin-to-strain coupling and could be used in hybrid spin-mechanical devices. In particular, this is the case for chromium. Here, the authors show that the spin dynamics of an individual Cr atom embedded in a quantum dot is controlled by the interaction with nonequilibrium phonons. Excitation conditions are found where the Cr spin states can be optically initialized, conserved in the dark for a few microseconds, and read out by resonant fluorescence.