Electron spin relaxation of single phosphorus donors and donor clusters in atomically engineered silicon devices

We demonstrate the single-shot spin read-out of single donors and few-donor clusters, positioned with atomic precision by scanning tunneling microscopy (STM) in atomically engineered silicon devices [1-3]. In donor clusters, we measure spin lifetimes of up to half a minute, recorded at a read-out fidelity of up to 99.8% [2]. Importantly, measuring spin relaxations rates of electrons bound to a single P donor in orientation-dependent electric and magnetic fields, we identify a previously unreported spin relaxation pathway for donor-based qubits in silicon [1].