L Marseglia

Multiple intrinsically identical single-photon emitters in the solid state

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(-)) 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.

Nanofabricated solid immersion lenses registered to single emitters in diamond

We describe a technique for fabricating micro- and nanostructures incorporating fluorescent defects in diamond with a positional accuracy better than hundreds of nanometers. Using confocal fluorescence microscopy and focused ion beam etching, we initially locate a suitable defect with respect to registration marks on the diamond surface then etch a structure using these coordinates. We demonstrate the technique by etching an 8 μm diameter hemisphere positioned with single negatively charged nitrogen-vacancy defect lies at its origin. Direct comparison of the fluorescence photon count rate before and after fabrication shows an eightfold increase due to the presence of the hemisphere.

Precise qubit control beyond the rotating wave approximation

Fast and accurate quantum operations of a single spin in room-temperature solids are required in many modern scientific areas, for instance in quantum information, quantum metrology, and magnetometry. However, the accuracy is limited if the Rabi frequency of the control is comparable with the transition frequency of the qubit due to the breakdown of the rotating wave approximation (RWA). We report here an experimental implementation of a control method based on quantum optimal control theory which does not suffer from such restriction. We demonstrate the most commonly used single qubit rotations, i.e. - and ?-pulses, beyond the RWA regime with high fidelity and , respectively. They are in excellent agreement with the theoretical predictions, and . Furthermore, we perform two basic magnetic resonance experiments both in the rotating and the laboratory frames, where we are able to deliberately ?switch? between the frames, to confirm the robustness of our control method. Our method is general, hence it may immediately find its wide applications in magnetic resonance, quantum computing, quantum optics, and broadband magnetometry.Jochen Scheuer, Xi Kong, Ressa S. Said, Jeson Chen, Andrea Kurz, Luca Marseglia, Jiangfeng Du, Philip R. Hemmer, Simone Montangero, Tommaso Calarco, Boris Naydenov, and Fedor Jelezko Institut für Quantenoptik, Albert-Einstein-Allee 11, Universität Ulm, 89069 Ulm, Germany Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China Institut für Quanteninformationsverarbeitung, Albert-Einstein-Allee 11, Universität Ulm, 89069 Ulm, Germany Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA

On-Chip Manipulation of Single Photons from a Diamond Defect

Operating reconfigurable quantum circuits with single photon sources is a key goal of photonic quantum information science and technology. We use an integrated waveguide device containing directional couplers and a reconfigurable thermal phase controller to manipulate single photons emitted from a chromium related color center in diamond. Observation of both a wavelike interference pattern and particlelike sub-Poissionian autocorrelation functions demonstrates coherent manipulation of single photons emitted from the chromium related center and verifies wave particle duality.