Tolerating Device Failure in Distributed Quantum Computing

TL;DR

This paper explores how distributed quantum computers can tolerate component failures using quantum error correction, maintaining logical error rates despite node failures, and compares code performances.

Contribution

It demonstrates that modular quantum networks with error correction can sustain operation during component failures, highlighting the effectiveness of toric and hyperbolic Floquet codes.

Findings

Quantum devices can be swapped during operation with minimal impact on error rates.

Toric and hyperbolic Floquet codes maintain logical information under node failures.

Distributed toric code outperforms monolithic implementation below 0.05% error rate during catastrophic failure.

Abstract

It is desirable that a distributed quantum computer can operate despite the replacement or failure of its constituent components, allowing the reliability of the distributed system to exceed that of its subcomponents. We first show that when quantum error correction is performed over a modular quantum network, quantum devices can be swapped out or replaced, during operation, with minimal impact on logical error rates. We also investigate the ability of the toric and hyperbolic Floquet quantum error correcting codes to protect logical information under low rates of modular node failure. In particular, we show that under the proposed distributed quantum error scheme, the selected codes are able to maintain good logical error suppression during the failure of entire nodes. For catastrophic node failure of probability p/100, we suggest that a distributed toric code would outperform one implemented on a monolithic device below a physical error rate of 0.05%.