Electron spin relaxations of phosphorus donors in bulk silicon under large electric field

Abstract

Modulation of donor electron wavefunction via electric fields is vital to quantum computing architectures based on donor spins in silicon. For practical and scalable applications, the donor-based qubits must retain sufficiently long coherence times in any realistic experimental conditions. Here, we present pulsed electron spin resonance studies on the longitudinal (T-1) and transverse (T-2) relaxation times of phosphorus donors in bulk silicon with various electric field strengths up to near avalanche breakdown in high magnetic fields of about 1.2 T and low temperatures of about 8 K. We find that the T-1 relaxation time is significantly reduced under large electric fields due to electric current, and T-2 is affected as the T-1 process can dominate decoherence. Furthermore, we show that the magnetoresistance effect in silicon can be exploited as a means to combat the reduction in the coherence times. While qubit coherence times must be much longer than quantum gate times, electrically accelerated T-1 can be found useful when qubit state initialization relies on thermal equilibration.