A Rydberg blockade CNOT gate and entanglement in a 2D array of neutral atom qubits

We present experimental results on two-qubit Rydberg blockade quantum gates and entanglement in a two-dimensional qubit array. Without post selection against atom loss we achieve a Bell state fidelity of \(0.73\pm 0.05\), the highest value reported to date. The experiments are performed in an array of single Cs atom qubits with a site to site spacing of \(3.8 ~ \mu\rm m\). Using the standard protocol for a Rydberg blockade C\(_Z\) gate together with single qubit operations we create Bell states and measure their fidelity using parity oscillations. We analyze the role of AC Stark shifts that occur when using two-photon Rydberg excitation and show how to tune experimental conditions for optimal gate fidelity.