Parity Measurements using Dispersive Shifts for Surface Codes

Abstract: Parity measurements are central to quantum error correction (QEC). In current implementations measurements of stabilizers are performed using a number of Controlled Not (CNOT) gates. This implementation suffers from an exponential decrease in fidelity as the number of CNOT gates increases thus the stabilizer measurements also suffer a severe decrease in fidelity and increase in gate time. Speeding up and improving the fidelity of this process will improve error rates of these stabilizer measurements thus increasing the coherence times of logical qubits. We propose a single shot method useful for stabilizer readout based on dispersive shifts. We show a possible set up for this method and simulate a 4 qubit system showing that this method is an improvement over the previous CNOT circuit in both fidelity and gate time. We find a fidelity of 99.8% and gate time of 600 ns using our method and investigate the effects of higher order Z interactions on the system.