Assessing quantum dot SWAP gate fidelity using tensor network methods

TL;DR

This paper uses tensor network methods to evaluate the fidelity of quantum dot SWAP gates in multi-qubit systems, revealing robustness against certain parameters and analyzing error scaling in long chains.

Contribution

It introduces tensor network techniques to assess SWAP gate fidelity in quantum dot systems with valley effects and crosstalk, providing new insights into error sources and scaling behaviors.

Findings

Fidelity unaffected by Zeeman and valley splitting unless in resonance

Valley phase has negligible effect on valley eigenstates

Crosstalk dominates error scaling in long qubit chains

Abstract

Advanced tensor network numerical methods are used to explore the fidelity of repeated SWAP operations on a system comprising 20-100 quantum dot spin qubits in the presence of valley leakage and electrostatic crosstalk. The fidelity of SWAP gates is largely unaffected by Zeeman splitting and valley splitting, except when these parameters come into resonance. The fidelity remains independent of the overall valley phase for valley eigenstates, while for generic valley states, some minor corrections arise. We analyze the fidelity scaling for long qubit chains without valley effects, where crosstalk represents the only error source.