Physical model of continuous two-qubit parity measurement in a cavity-QED network

TL;DR

This paper presents a physical implementation of continuous two-qubit parity measurement in a cavity-QED network, using sequential scattering of a probe beam and homodyne detection, supported by quantum stochastic differential equations modeling.

Contribution

It introduces a cavity-QED based scheme for continuous two-qubit parity measurement with a rigorous convergence analysis and numerical performance evaluation.

Findings

The scheme effectively performs parity measurement with realistic parameters.

Quantum stochastic differential equations accurately model the system dynamics.

Numerical simulations demonstrate practical feasibility.

Abstract

We propose and analyze a physical implementation of two-qubit parity measurements as required for continuous error correction, assuming a setup in which the individual qubits are strongly coupled to separate optical cavities. A single optical probe beam scatters sequentially from the two cavities and the continuous parity measurement is realized via fixed quadrature homodyne photo-detection. We present models based on quantum stochastic differential equations (QSDE's) for both an ideal continuous parity measurement and our proposed cavity quantum electrodynamics (cavity QED) implementation; a recent adiabatic elimination theorem for QSDE's is used to assert strong convergence of the latter to the former in an appropriate limit of physical parameters. Performance of the cavity QED scheme is studied via numerical simulation with experimentally realistic parameters.