Two-photon quantum interference from separate nitrogen vacancy centers in diamond

TL;DR

This paper demonstrates quantum interference between emissions from two separate nitrogen vacancy centers in diamond, showing potential for quantum networking and entanglement of solid-state spins.

Contribution

It reports the first observation of two-photon quantum interference from separate NV centers, including interference from dissimilar centers tuned via the Stark effect.

Findings

Two-photon interference contrast reaches 66%.

Quantum interference observed from dissimilar NV centers.

Results enable measurement-based entanglement for quantum networks.

Abstract

We report on the observation of quantum interference of the emission from two separate nitrogen vacancy (NV) centers in diamond. Taking advantage of optically induced spin polarization in combination with polarization filtering, we isolate a single transition within the zero-phonon line of the non-resonantly excited NV centers. The time-resolved two-photon interference contrast of this filtered emission reaches 66%. Furthermore, we observe quantum interference from dissimilar NV centers tuned into resonance through the dc Stark effect. These results pave the way towards measurement-based entanglement between remote NV centers and the realization of quantum networks with solid-state spins.