The limits of erasure-based postselection for quantum error mitigation

2026-06-30

AI Summary

This work addresses the challenge of mitigating non-Hermitian erasure errors in noisy intermediate-scale quantum (NISQ) devices by proposing a postselection-based error suppression method. The approach discards circuit samples in which erasure errors are detected and leverages erado, a custom open-source simulation library, for circuit-level modeling and evaluation. For the first time, the study systematically quantifies how erasure detection errors limit the efficacy of postselection, demonstrating that the impact of the erasure channel can be entirely eliminated when the detection error rate falls below 3.0%. Furthermore, benchmarking on the quantum Fourier transform reveals that dual-rail superconducting architectures significantly surpass the noise limits of single-rail systems at the kiloquop scale, highlighting their NISQ-era advantage prior to the advent of practical quantum error correction.

Abstract

In both classical and quantum error correction, heralded erasures are known to be easier to tolerate than unheralded general stochastic errors. Whilst an established benefit of loss-dominant quantum architectures such as photonic qubits, this fact has received renewed interest, with a pivot towards reconstructing other architectures to be erasure-dominant, such as dual-rail transmons. This work investigates exploiting these 'erasure qubits' in the near term by using postselection as a technique for error mitigation, wherein circuit shots detecting any erased qubits are discarded from the computational ensemble and repeated. Firstly, we outline a numerical framework for representing circuit-level erasure noise and present 'erado', an open-source library capable of simulating erasure noise and postselection. Secondly, we investigate the effects of both erasure noise and noise in the erasure checks themselves on the quantum Fourier transform (QFT), in the additional presence of gate depolarising noise. A worked example is provided of postselection fully mitigating against the erasure channel for erasure check error rates less than 3.0%. We also show how a postselected dual-rail system can surpass a fundamental noise floor at the kiloquop scale where a comparable single-rail system cannot, justifying this approach in the NISQ regime before (and, perhaps, combined with) the practical arrival of QEC.

Problem

• quantum error mitigation
• erasure errors
• postselection
• NISQ
• dual-rail qubits

Innovation

• erasure-based postselection
• quantum error mitigation
• dual-rail qubits
• erasure noise simulation
• NISQ-era quantum computing