Feedback-based active reset of a spin qubit in silicon

TL;DR

This paper demonstrates an active reset method for silicon spin qubits using feedback control and quantum non-demolition readout, improving initialization fidelity for fault-tolerant quantum computing.

Contribution

It introduces a feedback-based active reset protocol with cumulative readout, enhancing qubit initialization fidelity beyond previous limits.

Findings

Active reset achieves high fidelity in silicon spin qubits.

Cumulative readout improves reset accuracy.

Protocol approaches fidelity levels needed for fault-tolerant quantum computation.

Abstract

Feedback control of qubits is a highly demanded technique for advanced quantum information protocols such as quantum error correction. Here we demonstrate active reset of a silicon spin qubit using feedback control. The active reset is based on quantum non-demolition readout of the qubit and feedback according to the readout results, which is enabled by hardware data processing and sequencing. We incorporate a cumulative readout technique to the active reset protocol, enhancing initialization fidelity above a limitation imposed by accuracy of the single QND measurement fidelity. Based on an analysis of the reset protocol, we suggest a way to achieve the initialization fidelity sufficient for the fault-tolerant quantum computation.