Towards integrating high-fidelity two-qubit Rydberg gates with a photonic interface for neutral atom arrays

Neutral atoms are a powerful platform for quantum simulation and computation. Scaling to millions of qubits may require a modular architecture in which separate atom arrays are linked by photonic interconnects. Such links also enable long-distance quantum communication and distributed sensing. These applications require both high-rate remote entanglement generation and high-fidelity local two-qubit gates. Optical microcavities can significantly increase remote entanglement rates, while local two-qubit gates are commonly mediated by excitation to Rydberg states. However, surface charges near microcavities can produce stray electric fields that reduce Rydberg gate fidelities.

Here, we investigate surface charging around microcavities to assess the feasibility of Rydberg gates. To measure local electric fields, we place microcavities in a rubidium vapor and perform Rydberg EIT spectroscopy. Electric fields induce Stark shifts and splittings of Rydberg levels, providing a local probe of the field. We measure fields of ~0.2 V/cm at a distance of 50 µm from the cavity surface, with a decay length of ~0.5 mm. By incorporating conductive coatings near the mirrors, we expect to further suppress these fields and enable integration of Rydberg gates with a microcavity-based photonic interface.