Coherence control via dynamical decoupling of an electron spin in a quantum dot

An electron spin in a quantum dot is a promising system for applications in coherent spintronics and quantum computation, but the interaction with the nuclear spins leads to fast decoherence. Subjecting the electron spin to a suitable pulsed control field decouples it from the nuclear spin bath and suppresses decoherence. We study numerically and analytically several most promising decoupling protocols, taking into account the intra-bath coupling, using fully quantum mechanical treatment of the system plus bath dynamics. We show that some high-level protocols extend the coherence time by 3 orders of magnitude for an arbitrary initial spin state. Moreover, we present the protocols which preserve a known initial state with near-to-optimal fidelity for arbitrarily long times.