$^{29}$Si nuclear spins as a resource for donor spin qubits in silicon

TL;DR

This paper explores the use of nearby $^{29}$Si nuclear spins around donor atoms in silicon as a robust quantum register, demonstrating significantly enhanced coherence times and potential for multi-round quantum error correction in silicon-based quantum computing.

Contribution

It introduces a method to utilize $^{29}$Si nuclear spins as long-lived quantum registers coupled with donor spins, with theoretical strategies for error correction and spin protection.

Findings

$^{29}$Si nuclear spins have coherence times over two orders of magnitude greater than bulk silicon.

Donor electron spins effectively protect nearby nuclear spins from decoherence.

The proposed approach enables multi-round quantum error correction in silicon quantum devices.

Abstract

Nuclear spin registers in the vicinity of electron spins in solid state systems offer a powerful resource to address the challenge of scalability in quantum architectures. We investigate here the properties of $^{29}$Si nuclear spins surrounding donor atoms in silicon, and consider the use of such spins, combined with the donor nuclear spin, as a quantum register coupled to the donor electron spin. We find the coherence of the nearby $^{29}$Si nuclear spins is effectively protected by the presence of the donor electron spin, leading to coherence times in the second timescale - over two orders of magnitude greater than the coherence times in bulk silicon. We theoretically investigate the use of such a register for quantum error correction, including methods to protect nuclear spins from the ionisation/neutralisation of the donor, which is necessary for the re-initialisation of the ancillae qubits. This provides a route for multi-round quantum error correction using donors in silicon.