Speaker – Dr Jun Yoneda, UNSW Sydney:
Although single-shot measurement of a silicon electron spin qubit is now a laboratory routine, the quantum non-demolition (QND) implementation remains a key challenge towards error correction. A QND spin readout is distinct in that it imposes minimal disturbance to the measured spin polarization and is therefore repeatable. In this talk, we report a QND readout of a single electron spin in a Si/SiGe quantum dot by probing an ancilla electron spin in a neighbouring dot. We construct and characterize a cumulative QND readout process with over 20 repetitions of ancilla-based spin measurements, through the non-demolition, measurement and preparation fidelities. We further discuss a method of heralded high-fidelity ground-state preparation.