Deterministic nanoassembly of a coupled quantum emitter–photonic crystal cavity system

Abstract

Controlling the interaction of a single quantum emitter with its environment is a key challenge in quantum optics. Here, we demonstrate deterministic coupling of single nitrogen-vacancy ͑NV͒ centers to high-quality photonic crystal cavities. We preselect single NV centers and position their 50-nm-sized host nanocrystals into the mode maximum of photonic crystal S1 cavities with few-nanometer accuracy. The coupling results in a strong enhancement of NV center emission at the cavity wavelength. © 2011 American Institute of Physics. ͓doi:10.1063/1.3571437͔Spontaneous light emission can be controlled by enhancing or suppressing the vacuum fluctuations of the electromagnetic field at the location of the light source. 1 When placed into highly confined optical fields, such as those created in optical cavities or plasmonic structures, the optical properties of single quantum emitters can change drastically. [2][3][4][5] In particular, photonic crystal ͑PC͒ cavities show high quality factors combined with an extremely small mode volume. 6 It is challenging however to efficiently couple single photon sources to a PC cavity because the emitter has to be positioned in the localized optical mode, which is confined to an extremely small volume with a size of about a wavelength. [7][8][9] Nitrogen-vacancy ͑NV͒ centers in diamond are promising candidates for application as solid state quantum bits. [10][11][12] Long distance entanglement between NV centers enabling quantum repeater protocols may be achieved by two-photon quantum interference, 13,14 but is hindered by the NV centers' weak coherent photon emission rate. Being able to control and reshape the emission spectrum of a single NV center is therefore not only of fundamental interest but could also have potential applications in solid state quantum information processing. 15 Fabrication of high-quality PC cavities in diamond would be a natural way to control the emission properties of embedded NV centers but this is challenging because of the difficulties in growing and etching diamond single-crystal thin films. 16,17 An alternative, hybrid approach is to position a diamond nanocrystal with a single NV center near a PC cavity of a different material. [18][19][20][21] Because of the small size of such a crystal, the NV center can be placed in the highly confined optical mode where coupling can be efficient.Here, we demonstrate the deterministic nanoassembly of coupled single NV center-PC cavity systems by positioning ϳ50 nm sized diamond nanocrystals into gallium phosphide S1 cavities located on a different chip. The S1 cavity offers unique advantages over the well-studied L3 cavity. 19,20 Whereas in the L3 cavity the mode maximum is confined within the dielectric material, the mode maximum of the S1 cavity is localized in the air holes surrounding the cavity, making it accessible for coupling to external emitters. We are able to pick up and place a preselected diamond nanocrystal exactly into the mode maximum of a PC cavity, due to the versatility of our nanopositioning ...

One- and two-dimensional photonic crystal microcavities in single crystal diamond

“…The first route is to assemble hybrid systems where colour centres in diamond nanocrystals or bulk diamond are coupled to the evanescent fields of cavities defined in non-diamond materials for which established nano-fabrication techniques exist: here coupling to silica micro-spheres [19,20], silica micro-disks [21], GaP micro-disks [22] and GaP micro-ring cavities [23] has been demonstrated. In a very similar fashion recent experiments have realised controlled coupling of NV − centres in nanodiamonds to GaP photonic crystal cavities [24,25,26]. In these experiments selective enhancement of the NV − ZPL could be detected in the cavity emission spectrum.…”

Hybrid Nanocavity Resonant Enhancement of Color Center Emission in Diamond

“…Local modification of the GaP properties by the green excitation laser, as reported in Ref. [15], may also affect the device characteristics.…”

“…Efforts to efficiently couple NVs in nanocrystalline diamond to nanophotonic structures [12][13][14][15] have been limited by poor NV optical properties in nanocrystals compared to those found in single crystal diamond. Fabricating nanophotonic devices directly from single crystal diamond has recently made important progress [11,16,17], limited primarily by fabrication difficulties related to creating thin films of single crystal diamond necessary for optical confinement in three dimensions.…”

Design and low-temperature characterization of a tunable microcavity for diamond-based quantum networks

“…6 Purcell enhancement of the ZPL has been demonstrated in several cavity architectures such as diamond photonic crystal cavities, 7-11 microring resonators, 12 and hybrid structures with evanescently coupled nanodiamonds. [13][14][15][16] In recent years, the open Fabry-Perot microcavity 17 has emerged as a promising platform for diamond emitters. [18][19][20][21][22] Such a microcavity provides in-situ spatial and spectral tunability, while reaching strong field confinement due to its small mode volume V and high quality factor Q.…”