Sub-ensemble qubit measurements in neutral atom quantum computers using state-selective EIT

The ability to measure a sub-ensemble of qubits is needed for both quantum error correction (QEC) and one-way quantum computation. However, in atomic systems it is difficult to protect nearby quantum information while some qubits are being measured. We propose a method to achieve this sub-ensemble state detection for neutral atom qubits using a combination of site-selective state transfers and electromagnetically-induced transparency (EIT). First, the qubits to be measured will be transferred out of the qubit basis and into two auxiliary magnetic sublevels. Second, EIT light will be turned on to protect all the magnetic sublevels except for one that is needed for detection. Both qubit states can be measured in turn, to check for atom loss. The measured atoms can be recooled and reinitialized into the qubit basis after detection. A simple extension of this method can also be used to measure qubit leakage errors. We will present our calculations for Cs but expect that the central ideas can be extended to other atomic systems.