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

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 ${\mathcal{F}}_{\mathrm{QND}}=0.933(12)$ and $0.865(17)$ for two- and three-qubit plaquettes, respectively.

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