Coherent spin qubit transport in silicon

TL;DR

This paper demonstrates high-fidelity coherent transport of an electron spin qubit in silicon, a crucial step towards scalable quantum processors with reduced qubit overheads by enabling on-chip qubit connectivity.

Contribution

It provides the first high-fidelity demonstration of coherent spin qubit transport in silicon, supporting scalable quantum computing architectures.

Findings

Polarization transfer fidelity of 99.97%

Average coherent transfer fidelity of 99.4%

Observation of qubit precession during tunnelling

Abstract

A fault-tolerant quantum processor may be configured using stationary qubits interacting only with their nearest neighbours, but at the cost of significant overheads in physical qubits per logical qubit. Such overheads could be reduced by coherently transporting qubits across the chip, allowing connectivity beyond immediate neighbours. Here we demonstrate high-fidelity coherent transport of an electron spin qubit between quantum dots in isotopically-enriched silicon. We observe qubit precession in the inter-site tunnelling regime and assess the impact of qubit transport using Ramsey interferometry and quantum state tomography techniques. We report a polarization transfer fidelity of 99.97% and an average coherent transfer fidelity of 99.4%. Our results provide key elements for high-fidelity, on-chip quantum information distribution, as long envisaged, reinforcing the scaling prospects of silicon-based spin qubits.