Practicality of spin chain 'wiring' in diamond quantum technologies

TL;DR

This paper evaluates the feasibility of using spin chains in diamond for quantum wiring, finding they are more suitable as mediators of noisy entanglement than for high-fidelity quantum state transfer.

Contribution

It provides a detailed analysis of error effects in spin chain wiring in diamond quantum systems and proposes their use as entanglement mediators with purification, bypassing nearest-neighbor constraints.

Findings

Finite entangling power with T2 > 0.55 ms

Chain can mediate noisy entanglement effectively

Re-purposing chain removes need for dynamical decoupling

Abstract

Coupled spin chains are promising candidates for 'wiring up' qubits in solid-state quantum computing (QC). In particular, two nitrogen-vacancy centers in diamond can be connected by a chain of implanted nitrogen impurities; when driven by a suitable global fields the chain can potentially enable quantum state transfer at room temperature. However, our detailed analysis of error effects suggests that foreseeable systems may fall far short of the fidelities required for QC. Fortunately the chain can function in the more modest role as a mediator of noisy entanglement, enabling QC provided that we use subsequent purification. For instance, a chain of 5 spins with inter-spin distances of 10 nm has finite entangling power as long as the T2 time of the spins exceeds 0.55 ms. Moreover we show that re-purposing the chain this way can remove the restriction to nearest-neighbor interactions, so eliminating the need for complicated dynamical decoupling sequences.