Discrete-variable assisted error correction of continuous-variable quantum information

TL;DR

This paper introduces a new continuous-variable quantum error correction method using accessible discrete-variable ancillas, enabling effective error suppression without relying on GKP states.

Contribution

It proposes a CV QEC scheme utilizing DV ancillas for error correction, avoiding the demanding GKP state preparation, and demonstrates its robustness and practical potential.

Findings

Single-qubit ancilla suppresses CV infidelity by over 20%

Concatenation with DV QEC codes enhances robustness against physical errors

Yields a new oscillator-in-oscillator code without GKP states

Abstract

Robust continuous-variable (CV) quantum information processing requires correcting realistic errors in bosonic systems, but all existing schemes rely on auxiliary Gottesman-Kitaev-Preskill (GKP) states which the preparation and operation are demanding in many platforms. In this work, we propose a novel CV quantum error correction (QEC) scheme that utilizes a broadly accessible resource: discrete-variable (DV) ancilla. Our scheme extracts information about CV displacement to the DV ancilla, measuring that allows counteracting the unwanted displacement error. We show that a simple single-qubit ancilla can already suppress CV infidelity by more than 20%. By concatenating with DV QEC codes, our scheme is robust against the physical errors in hybrid CV-DV systems, and yields a new class of oscillator-in-oscillator code that does not involve GKP states. Our work facilitates the implementation of CV QEC on realistic platforms.