Indistinguishable Photons from Separated Silicon-Vacancy Centers in Diamond

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Indistinguishable Photons from Separated Silicon-Vacancy Centers in Diamond

A. Sipahigil, K. D. Jahnke, L. J. Rogers, T. Teraji, J. Isoya, A. S. Zibrov, F. Jelezko, and M. D. Lukin

Phys. Rev. Lett. 113, 113602 – Published 11 September 2014

See Viewpoint: Diamond and Silicon Get Entangled

Abstract

We demonstrate that silicon-vacancy (SiV) centers in diamond can be used to efficiently generate coherent optical photons with excellent spectral properties. We show that these features are due to the inversion symmetry associated with SiV centers. The generation of indistinguishable single photons from separated emitters at 5 K is demonstrated in a Hong-Ou-Mandel interference experiment. Prospects for realizing efficient quantum network nodes using SiV centers are discussed.

Received 30 June 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.113602

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Viewpoint

Diamond and Silicon Get Entangled

Published 11 September 2014

Two silicon-vacancy centers in diamond can emit photons that are indistinguishable—suggesting they have potential as building blocks for a diamond-based quantum computer.

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Authors & Affiliations

A. Sipahigil^1,*, K. D. Jahnke², L. J. Rogers², T. Teraji³, J. Isoya⁴, A. S. Zibrov¹, F. Jelezko², and M. D. Lukin¹

¹Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA
²Institute for Quantum Optics, University Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
³National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
⁴Research Center for Knowledge Communities, University of Tsukuba, 1-2 Kasuga, Tsukuba, Ibaraki 305-8550, Japan

^*sipahigil@physics.harvard.edu

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Issue

Vol. 113, Iss. 11 — 12 September 2014

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Images

Figure 1
Electronic structure and optical transitions of the SiV center. (a) The center is aligned along a $⟨ 111 ⟩$ axis of the diamond host crystal, with the silicon atom (Si) located in the middle of two empty lattice sites. The system has $D_{3 d}$ symmetry which includes inversion symmetry. (b) The optical transition is between different parity states, ${}^{2}{E_{u}}$ and ${}^{2}{E_{g}}$ . Spin orbit interaction ( $λ_{u}^{SO} \sim 250 GHz$ , $λ_{g}^{SO} \sim 50 GHz$ ) partially lifts the degeneracy giving rise to doublets in the ground and excited states. Transitions $A$ , $B$ , $C$ , $D$ are all dipole allowed. (c) The emission spectrum measured using off-resonant excitation at 532 nm on a single SiV center at 4.5 K.
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Figure 2
Schematic of the two-channel confocal microscope built for the HOM experiment. (a) Channels I and II were used to address different emitters separated by tens of micrometers in the same sample. A continuous-wave 532-nm laser was used for excitation, and fluorescence was collected in single-mode fibers on ZPL and PSB ports simultaneously. (b) Collected ZPL fluorescence from the two channels were directed onto a free-space $50 ∶ 50$ nonpolarizing beam splitter. Linear polarizers were used to control the polarization of the single photons varying their distinguishability. Etalons were used to filter transition $C$ before detection. (c) Emission spectrum before (brown) and after the etalons (blue).
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Figure 3
Inhomogeneous distribution of SiV centers. (a) The probe laser frequency was fixed to the ensemble average of $ν_{0} = 406.7001 THz$ for transition $C$ while scanning the sample. A high density of resonant emitters is visible with a large background. The color bar applies to (a)–(d). (b) Scan of the same region with the laser tuned to $ν_{1} = ν_{0} + 1.5 GHz$ . Because of the narrow inhomogeneous distribution, only few resonant sites are visible, and the background level is low. (c) and (d) show the two emitters, ${SiV}_{I}$ and ${SiV}_{II}$ , used for the HOM interference experiment at frequency $ν \sim ν_{1}$ . (e) PLE spectrum for ${SiV}_{I}$ (green) and ${SiV}_{II}$ (pink) with measured FWHM of 135.8 and 134.6 MHz, respectively, and lines separated by 52.1 MHz.
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Figure 4
HOM interference experiment. The second-order intensity correlation function $g^{2} (τ)$ is plotted for two cases: (i) pink data show the results for indistinguishable single photons with identical polarizations, $g_{∥}^{2} (0) = 0.26 \pm 0.05$ . The error bars denote shot noise estimates. (ii) Green data show the results when photons from one emitter are orthogonally polarized and hence distinguishable, $g_{⊥}^{2} (0) = 0.66 \pm 0.08$ . The blue and brown solid lines represent our model using independently measured parameters, only fitting a single parameter for background events in both datasets.
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