To­wards Quantum Re­peater Based on Color Cen­ters in Dia­mond Nano­struc­tures

In recent years much progress has been made toward the realization of quantum information processing (QIP) based upon nitrogen-vacancy (NV) centers in diamond formed by a two-point defect in the diamond lattice: a substitutional nitrogen atom and a vacancy trapped at an adjacent lattice position. For example, long ground state electron spin coherence times have been observed, full electron spin control has been achieved using optically-detected magnetic resonance, and electron-nuclear qubit transfer, necessary for long quantum memory times, has been performed. However, such demonstrations so far have involved manipulation only of isolated NV centers.

For realization of large-scale QIP or for quantum repeaters it will be necessary to connect NV centers together through “flying" qubits such as photons, i.e. ensembles or at least pairs of NV centers are required. To achieve this, optical structures in diamond such as microcavities and waveguides are needed to enable transfer of quantum information between the electron spin of the NV center and a photon. In general there are two approaches to couple NV centers to an optical device. The first one is to couple NV centers in a diamond nanoparticle to a microcavity, e.g. in SiO2. The second approach includes the fabrication of optical structures out of diamond. 

The coupling of NV centers to diamond optical devices is one of the major tasks of our current research in frame of the BMBF Q.com-H project with the investigation of the possibility for its application as quantum repeater.

Pro­ject Part­ners

  • Prof. Jorg Wrachtrup, 3. Physikalisches Institut, University of Stuttgart, Germany
  • Prof. Fedor Jelezko, PD Dr. Boris Naydenov, Institute of Quantum Optics, University of Ulm, Germany
  • Prof. Meir Orenstein, Technion, Haifa, Israel

Se­lec­ted pub­lic­a­tions

Pic­ture gal­lery

Fig. 1: Physica Status Solidi B cover (January 2013).
Fig. 1: Physica Status Solidi B cover (January 2013).
Fig. 2: PL spectrum of NCD nanopillar.
Fig. 2: PL spectrum of NCD nanopillar.
Fig. 3: Diamond nanocrystallites with NV centers grown on pre-patterned Si substrate.
Fig. 3: Diamond nanocrystallites with NV centers grown on pre-patterned Si substrate.
Fig. 4: Photonic crystal structure in NCD membrane.
Fig. 4: Photonic crystal structure in NCD membrane.
Fig. 5: Fluorescence of NCD photonic crystal.
Fig. 5: Fluorescence of NCD photonic crystal.
Fig. 6: Schema of a SiV center in the diamond crystal lattice.
Fig. 6: Schema of a SiV center in the diamond crystal lattice.
Fig. 7: Schematic diagram of the fabrication process of diamond nanopillars with incorporated SiV centers.
Fig. 7: Schematic diagram of the fabrication process of diamond nanopillars with incorporated SiV centers.
Fig. 8: Confocal images showing the fluorescence of arrays of diamond nanopillars with diameters of 1 µm (a) and 100 nm (b).
Fig. 8: Confocal images showing the fluorescence of arrays of diamond nanopillars with diameters of 1 µm (a) and 100 nm (b).
Fig. 9: Integration of quantum dots with NCD layer.
Fig. 9: Integration of quantum dots with NCD layer.
Fig. 10: NCD layer on top of GaAs substrates with surface and buried quantum dots.
Fig. 10: NCD layer on top of GaAs substrates with surface and buried quantum dots.