  Electron spin qubit in a quantum dot has been studied extensively for
scalable quantum information processing over the past two decades. Recently,
high-fidelity and fast single-spin control and strong spin-photon coupling have
been demonstrated using a synthetic spin-orbit coupling created by a
micromagnet. Such strong electrical driving suggests a strongly coupled
spin-photon system. Here we study the relaxation, pure dephasing, and
electrical manipulation of a dressed-spin qubit based on a driven single
electron in a quantum dot. We find that the pure dephasing of a dressed qubit
due to charge noise can be suppressed substantially at a sweet spot of the
dressed qubit. The relaxation at low magnetic fields exhibits non-monotonic
behavior due to the energy compensation from the driving field. Moreover, the
longitudinal component of the synthetic spin-orbit field could provide fast
electric-dipole-induced dressed-spin resonance (EDDSR). Based on the slow
dephasing and fast EDDSR, we further propose a scheme for dressed-spin-based
semiconductor quantum computing.
