Bullseye dielectric cavities for photon collection from a surface-mounted quantum-light-emitter.

Coupling light from a point source to a propagating mode is an important problem in nano-photonics and is essential for many applications in quantum optics. Circular "bullseye" cavities, consisting of concentric rings of alternating refractive index, are a promising technology that can achieve near-unity coupling into a first lens. Here we design a bullseye structure suitable for enhancing the emission from dye molecules, 2D materials and nano-diamonds positioned on the surface of these cavities. A periodic design of cavity, meeting the Bragg scattering condition, achieves a Purcell factor of 22.5 and collection efficiency of 80%. We also tackle the more challenging task of designing a cavity for coupling to a low numerical aperture fibre in the near field. Finally, using an iterative procedure, we study how the collection efficiency varies with apodised (non-periodic) rings.

Super-Poissonian Light Statistics from Individual Silicon Vacancy Centers Coupled to a Laser-Written Diamond Waveguide.

Modifying light fields at the single-photon level is a key challenge for upcoming quantum technologies and can be realized in a scalable manner through integrated quantum photonics. Laser-written diamond photonics offers 3D fabrication capabilities and large mode-field diameters matched to fiber optic technology, though limiting the cooperativity at the single-emitter level. To realize large coupling efficiencies, we combine excitation of single shallow-implanted silicon vacancy centers via high numerical aperture optics with detection assisted by laser-written type-II waveguides. We demonstrate single-emitter extinction measurements with a cooperativity of 0.0050 and a relative beta factor of 13%. The transmission of resonant photons reveals single-photon subtraction from a quasi-coherent field resulting in super-Poissonian light statistics. Our architecture enables light field engineering in an integrated design on the single quantum level although the intrinsic cooperativity is low. Laser-written structures can be fabricated in three dimensions and with a natural connectivity to optical fiber arrays.

Room-Temperature Quantum Emitter in Aluminum Nitride.

A device that is able to produce single photons is a fundamental building block for a number of quantum technologies. Significant progress has been made in engineering quantum emission in the solid state, for instance, using semiconductor quantum dots as well as defect sites in bulk and two-dimensional materials. Here we report the discovery of a room-temperature quantum emitter embedded deep within the band gap of aluminum nitride. Using spectral, polarization, and photon-counting time-resolved measurements we demonstrate bright (>105 counts s-1), pure (g (2)(0) < 0.2), and polarized room-temperature quantum light emission from color centers in this commercially important semiconductor.