Spin measurements of NV centers coupled to a photonic crystal cavity

Abstract

Nitrogen-vacancy (NV) centers feature outstanding properties like a spin coherence time of up to one second as well as a level structure offering the possibility to initialize, coherently manipulate and optically read-out the spin degree of freedom of the ground state. However, only about three percent of their photon emission are channeled into the zero phonon line (ZPL), limiting both the rate of indistinguishable single photons and the signal-to-noise ratio (SNR) of coherent spin-photon interfaces. We here report on the enhancement of the SNR of the optical spin read-out achieved by tuning the mode of a two-dimensional photonic crystal (PhC) cavity into resonance with the NV-ZPL. PhC cavities are fabricated by focused ion beam (FIB) milling in thin reactive ion (RIE) etched ultrapure single crystal diamond membranes featuring modes with Q-factors of up to 8250 at mode volumes below one cubic wavelength. NV centers are produced in the cavities in a controlled fashion by a high resolution atomic force microscope (AFM) implantation technique. On cavity resonance we observe a lifetime shortening from 9.0 ns to 8.0 ns as well as an enhancement of the ZPL emission by almost one order of magnitude. Although on resonance the collection efficiency of ZPL photons and the spin-dependent fluorescence contrast are reduced, the SNR of the optical spin read-out is almost tripled for the cavity-coupled NV centers.

Towards Real‐World Quantum Networks: A Review

“…First, single ions can be trapped easily for weeks and, thus, offer a much longer storage than that of single neutral atoms. [131] Second, the state of trapped ions can be detected near-deterministically by optical 171 Yb + . The transition 2 S 1∕2 to 2 P 1∕2 is pumped by a light with the wavelength of 369.5 nm.…”

“…[142] After the preparation of single ion-single photon entanglement, the photon can be used as a quantum bus to connect different nodes containing ions. In this spirit, in 2007, Moehring et al demonstrated the entanglement generation between two separated 171 Yb + . [143] In their experiment, two ions were trapped in two vacuum chambers separated by 1 m. The experimental apparatus is displayed in Figure 8.…”

“…[#0143], there were several experiments carried out with two separated trapped 171 Yb + ions and their nonclassical correlated photons. [144][145][146][147] In 2008, Matsukevich et al demonstrated the entanglement between two 171 Yb + ions separated by 1 m and further verified Bell inequality violation with ion-ion entanglement. [144] The experiment in ref.…”

“…Due to the experimental repetition of 75 kHz, the successful teleportation rate was about 0.083 per minute. At the same year, Maunz et al performed a heralded quantum gate between remote quantum memories consisting of single 171 Yb + ions and entangled them together [146] . The maximum efficiency of entangling gate generation was about 4.2 × 10 −8 .…”

Towards real-world quantum networks: a review

“…It is challenging to inhibit the phonon relaxation process and improve the photon emission efficiency via the ZPL. One approach is to couple the NV centers to cavities so as to enhance the ZPL via the Purcell effect [167,168].…”