Generating entanglement with low Q-factor microcavities

TL;DR

This paper introduces a method for generating entanglement using low Q-factor microcavities in resonance scattering regime, simplifying cavity fabrication and enabling non-demolition spin measurements.

Contribution

The work demonstrates a novel entanglement generation technique that operates with low Q-factor microcavities, reducing fabrication complexity compared to traditional high-Q approaches.

Findings

Resonance scattering enables entanglement with lower cavity quality factors.

The method allows non-demolition measurement of electron spins.

It simplifies cavity engineering in materials like diamond.

Abstract

We propose a method of generating entanglement using single photons and electron spins in the regime of resonance scattering. The technique involves matching the spontaneous emission rate of the spin dipole transition in bulk dielectric to the modified rate of spontaneous emission of the dipole coupled to the fundamental mode of an optical microcavity. We call this regime resonance scattering where interference between the input photons and those scattered by the resonantly coupled dipole transition result in a reflectivity of zero. The contrast between this and the unit reflectivity when the cavity is empty allow us to perform a non demolition measurement of the spin and to non deterministically generate entanglement between photons and spins. The chief advantage of working in the regime of resonance scattering is that the required cavity quality factors are orders of magnitude lower than is required for strong coupling, or Purcell enhancement. This makes engineering a suitable cavity much easier particularly in materials such as diamond where etching high quality factor cavities remains a significant challenge.