Diffusive entanglement generation by continuous homodyne monitoring of spontaneous emission

TL;DR

This paper compares homodyne detection and photodetection for generating entanglement between remote qubits via spontaneous emission, highlighting practical advantages of the diffusive homodyne approach.

Contribution

It demonstrates that homodyne detection achieves the same average entanglement as photodetection, offering a more feasible method for superconducting qubits.

Findings

Homodyne detection yields similar entanglement as photodetection.

Diffusive trajectories differ in two-qubit state dynamics.

Homodyne scheme is more practical for superconducting qubits.

Abstract

We consider protocols to generate quantum entanglement between two remote qubits, through joint time-continuous detection of their spontaneous emission. We demonstrate that schemes based on homodyne detection, leading to diffusive quantum trajectories, lead to identical average entanglement yield as comparable photodetection strategies; this is despite substantial differences in the two-qubit state dynamics between these schemes, which we explore in detail. The ability to use different measurements to achieve the same ends may be of practical significance; the less-well-known diffusive scheme appears far more feasible on superconducting qubit platforms in the near term.