Circuit-based leakage-to-erasure conversion in a neutral atom quantum processor

TL;DR

This paper demonstrates a circuit-based method to convert leakage errors into erasure errors in a neutral-atom quantum processor, improving error detection and correction capabilities for scalable quantum computing.

Contribution

It introduces Leakage Detection Units (LDUs) that non-destructively detect leakage errors and convert them to erasures, with a novel SWAP LDU circuit enabling atom refilling.

Findings

LDU detects atom-loss errors with ~93.4% accuracy

Successful conversion of leakage errors to erasures for major pathways

Implementation of a SWAP LDU for atom refilling

Abstract

Leakage out of the computational subspace is a major limitation of current state-of-the-art neutral-atom quantum computers and a significant challenge for scalable systems. In a quantum processor with cesium atoms, we demonstrate proof-of-principle circuit-based conversion of leakage errors to erasure errors via Leakage Detection Units (LDUs), which non-destructively map information about the presence or absence of the qubit onto the state of an ancilla. With a standard LDU circuit, we successfully convert leakage errors to erasure errors for all major leakage pathways while preserving the quantum information in the case that no leakage occurred. We benchmark the performance of the LDU using a three-outcome low-loss state detection method and also explore the advantages of three-outcome measurements for LDUs. We find that the LDU detects atom-loss errors with ~93.4% accuracy, limited by technical imperfections of our apparatus. We further compile and execute a SWAP LDU, wherein the roles of the original data atom and ancilla atom are exchanged under the action of the LDU, providing 'free refilling' of atoms in the case of leakage errors. This circuit-based leakage-to-erasure error conversion is a critical component of a neutral-atom quantum processor where the quantum information may significantly outlive the lifetime of any individual atom in the quantum register.