Parity Measurements using Dispersive Shifts for Surface Codes

TL;DR

This paper introduces a dispersive shift-based single shot method for stabilizer parity measurements in quantum error correction, demonstrating improved fidelity and speed over traditional CNOT-based approaches.

Contribution

The paper proposes a novel dispersive shift technique for stabilizer measurements, reducing gate time and increasing fidelity compared to conventional CNOT-based methods.

Findings

Achieved 99.8% fidelity in simulations

Reduced gate time to 600 ns

Demonstrated robustness against higher order Z interactions

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.