Engineering long spin coherence times of holes in silicon

Dr Joseph Salfi
4pm Thursday 22 February 2018
CQC2T Conference Room, Level 2, Newton Building J12, UNSW Kensington Campus

Future quantum technologies require quantum bits that remain coherent over long time scales, a goal recently achieved for electron spins in some semiconductors. Because of their strong spin-orbit coupling, hole-based qubits have attracted interest to achieve long-distance coupling, and to build hybrid quantum systems and spin/photon interfaces. However, it is not known if spin-orbit coupling of holes is compatible with long coherence times, since to date, experimentally reported values are too short for most envisioned applications. Here we show that holes bound to B:Si dopants in 28Si can be engineered to have spin coherence times rivalling electrons in 28Si. The results are obtained by directly controlling spin-phonon coupling and electric dipole components of the qubit responsible for decoherence, by applying a small strain to the silicon lattice. Thereby, we establish hole spins in silicon as a platform with coherence times rivalling electrons, and with tunable intrinsic spin-orbit coupling advantageous to build hybrid quantum systems and couple qubits over long distances.