Qubit syndrome measurements with a high fidelity Rb-Cs Rydberg gate

TL;DR

This paper reports a high-fidelity Rb-Cs Rydberg gate enabling quantum non-demolition measurements crucial for quantum error correction, demonstrated with multi-atom error syndrome measurements.

Contribution

First demonstration of an inter-species Rydberg gate with high fidelity enabling in-place QND qubit measurements for quantum error correction.

Findings

Achieved Rb-Cs Rydberg gate fidelity of 0.975

Demonstrated QND measurement fidelities of 0.933 and 0.865 for multi-qubit plaquettes

Enabled in-place quantum error syndrome measurements

Abstract

We demonstrate an inter-species entangling Rydberg gate between rubidium (Rb) and cesium (Cs) atoms with fidelity $\mathcal F = 0.975\pm 0.002$. The two-species atom array enables in-place quantum non-demolition (QND) qubit measurements which are a key capability for quantum error correction. We demonstrate this functionality with multi-atom error syndrome measurements achieving QND measurement fidelities of ${\mathcal F}_{\rm QND} = 0.933(12)$ and 0.865(17) for two- and three-qubit plaquettes, respectively.