Emitters of indistinguishable single photons are crucial for the growing field of quantum technologies. To realize scalability and increase the complexity of quantum optics technologies, multiple independent yet identical single-photon emitters are required. However, typical solid-state single-photon sources are inherently dissimilar, necessitating the use of electrical feedback or optical cavities to improve spectral overlap between distinct emitters. Here we demonstrate bright silicon vacancy (SiV À ) centres in low-strain bulk diamond, which show spectral overlap of up to 91% and nearly transform-limited excitation linewidths. This is the first time that distinct single-photon emitters in the solid state have shown intrinsically identical spectral properties. Our results have impact on the application of single-photon sources for quantum optics and cryptography.
The efficiency of collecting photons from optically active defect centres in bulk diamond is greatly reduced by refraction and reflection at the diamond-air interface. We report on the fabrication and measurement of a geometrical solution to the problem; integrated solid immersion lenses (SILs) etched directly into the surface of diamond. An increase of a factor of 10 was observed in the saturated count-rate from a single negatively charged nitrogen-vacancy (NV − ) within a 5 µm diameter SIL compared with NV − s under a planar surface in the same crystal. A factor of 3 reduction in background emission was also observed due to the reduced excitation volume with a SIL present. Such a system is potentially scalable and easily adaptable to other defect centres in bulk diamond.The ability to address single defect centres in diamond using confocal microscopy allows optical access to these single 'atom like' systems trapped within a macro-scale solid. The negatively charged nitrogenvacancy centre (NV − ) is of particular interest for applications such as single photon generation [1,2], nanoscale magnetometery [3], and fundamental investigations of spin interactions and entanglement at room temperature [4][5][6]. Other defect centres that exhibit single photon emission have also been identified (e.g. the nickel-related 'NE8' [7], the silicon-vacancy [8], and chromium related centres [9]), but the search continues for other defect centres with spin properties like those of the NV − centre [10]. The high refractive index of diamond causes refraction of the emitted light at the diamond-air interface, reducing the possible angular collection of a microscope objective. Thus the NV − photon collection efficiency is severely reduced. This is a problem regardless of the application, or of the particular defect centre of interest. Here we report on the fabrication and measurement of hemispherical integrated solid immersion lenses (SILs) etched directly into the surface of diamond. These structures eliminate surface refraction, thus increasing the numerical aperture (NA) of the microscope system. This allows a substantial increase in the resolution and background rejection of our system, along with a strong enhancement in NV − photon collection efficiency. Moreover, this geometrical solution can easily be applied to other defect centres in bulk diamond which emit at different wavelengths [11].The photon collection efficiency from NV − centres in diamond has previously been improved by using NV − centres located within nanocrystals small enough that the centres effectively emit into free space [2,12], or nanophotonic structures such as nanowires which guide emission towards collection [13]. Photon collection is increased by a factor of up to about 5 in the former case and 10 in the latter. However with the NV − centres positioned so close to the surface, local strain, impurities and other surface effects have been shown to degrade the stability, and spin coherence time of the NV − centre [14,15], so a solution which improves the p...
Until recently, quantum photonic architecture comprised of large-scale (bulk) optical elements, leading to severe limitations in miniaturization, scalability and stability. The development of the first integrated quantum optical circuitry removes this bottleneck and allows realization of quantum optical schemes whose greatly increased capacity for circuit complexity is crucial to the progress of experimental quantum information science and the development of practical quantum technologies.Integrated quantum photonic circuits within Silica-on-Silicon waveguide chips were simulated, designed and tested. Hundreds of devices have been fabricated with the core components found to be robust and highly repeatable. Amongst these demonstrations, all the basic components required for quantum information applications are shown. The first integrated quantum metrology experiments are demonstrated by beating the standard quantum limit with twoand four-photon entangled states while providing the first re-configurable integrated quantum circuit capable of adaptively controlling levels of non-classical interference of photons. The tested integrated devices show no limitations to obtain high quality performances. It is reported near-unity visibility of two-photon non-classical interference and a Controlled-NOT gate that could in principle work in the fault tolerant regime.It is demonstrated the realization of a compiled version of Shors quantum factoring algorithm on an integrated waveguide chip. This demonstration serves as an illustration to the importance of using integrated optics for quantum optical experiments.
Exploring the maximum spatial resolution achievable in far‐field optical imaging, we show that applying solid immersion lenses (SIL) in stimulated emission depletion (STED) microscopy addresses single spins with a resolution down to 2.4 ± 0.3 nm and with a localization precision of 0.09 nm.
applications in magnetic resonance, quantum computing, quantum optics, and broadband magnetometry., we apply a magnetic field 2 New J. Phys. 16 (2014) 093022 J Scheuer et al 7 New J. Phys. 16 (2014) 093022 J Scheuer et al
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