Zero field optical study of phosphorus donor spin resonance in enriched silicon

Donor spins in silicon are some of the most promising qubits for upcoming solid-state quantum technologies. The nuclear spins of phosphorus donors in enriched silicon have among the longest coherence times of any solid-state system as well as simultaneous qubit initialization, manipulation and readout fidelities near ~99.9\%. Here we characterize the phosphorus in silicon system in the regime of “zero” magnetic field, close to a singlet-triplet spin “clock transition”, using laser spectroscopy and magnetic resonance. We show the system can be optically hyperpolarized and has ∼10 s Hahn echo coherence times.