Noise-reduction of multimode Gaussian Boson Sampling circuits via Unitary Averaging

TL;DR

This paper enhances Gaussian Boson Sampling circuits by applying unitary averaging to reduce noise, improving fidelity and success probability in large-scale, noisy quantum systems, with practical implementation guidance.

Contribution

The work extends unitary averaging to mitigate various interferometric noise types in GBS circuits, providing a scalable performance prediction and implementation algorithm.

Findings

UA improves fidelity and success probability under noise

Performance gains follow a power-law in large systems

Applicable to 100-mode and 216-mode configurations

Abstract

We improve Gaussian Boson Sampling (GBS) circuits by integrating the unitary averaging (UA) protocol, previously demonstrated to protect unknown Gaussian states from phase errors [Phys. Rev. A 110, 032622]. Our work extends the applicability of UA to mitigate arbitrary interferometric noise, including beam-splitter and phase-shifter imperfections. Through comprehensive numerical analysis, we demonstrate that UA consistently achieves higher fidelity and success probability compared to unprotected circuits, establishing its robustness in noisy conditions. Remarkably, enhancement is maintained across varying numbers of modes with respect to the noise. We further derive a power-law formula predicting performance gains in large-scale systems, including 100-mode and 216-mode configurations. A detailed step-by-step algorithm for implementing the UA protocol is also provided, offering a practical roadmap for advancing near-term quantum technologies.