Towards high-fidelity alkali atom entanglement via single-photon Rydberg excitation and microwave dressing*

High-fidelity entangling gates are a crucial component of scalable quantum computing. Neutral atoms using Rydberg interactions have recently demonstrated entanglement fidelity below the threshold necessary for quantum error correction. In alkali atoms, Rydberg excitation is typically achieved via two-photon transitions. While, in principle, single-photon excitation eliminates errors due to intermediate-state scattering and the Stark shift inherent in the two-photon transition process, previous experimental demonstrations face several challenges. One of the key challenges is the drastically increased electric polarizability of nP_3/2 states which are excited with a single photon, compared to the nS_1/2 states that follow from two-photon excitation. Here, we propose a high-fidelity single-photon excitation entangling gate in Cesium, with microwave dressing of Rydberg levels to mitigate polarizability effects. We present our experimental progress toward implementing this approach.