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1.
Nat Mater ; 21(1): 8-9, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34795401
2.
Opt Lett ; 43(24): 6077-6080, 2018 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-30548008

RESUMEN

Direct femtosecond laser writing has been used to produce localized regions of photo-luminescent emission in 4H- and 6H-silicon carbide (SiC). Arrays of active color centers were fabricated by different pulse laser energies in the sites of square grids at various depths (from surface level to 10 µm below surface). We optically characterized the fabricated color centers using confocal imaging with 532 and 780 nm excitation, photo-luminescence spectroscopy, and lifetime decay at room temperature. We show that the technique can produce specifically the silicon vacancy color center emitting in the range 850-950 nm and other emitters in the 700 nm. This method can be adopted to engineer color centers in (SiC) at different depths in the material for single-photon generation, sensing, display fabrication, and light emitting diodes.

3.
Opt Express ; 26(6): 7056-7065, 2018 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-29609391

RESUMEN

We report progress in the development of tunable room temperature triggered single photon sources based on single nitrogen-vacancy (NV) centres in nanodiamond coupled to open access optical micro-cavities. The feeding of fluorescence from an NV centre into the cavity mode increases the spectral density of the emission and results in an output stream of triggered single photons with spectral line width of order 1 nm, tunable in the range 640 - 700 nm. We record single photon purities exceeding 96% and estimated device efficiencies up to 3%. We compare performance using plano-concave microcavities with radii of curvature from 25 µm to 4 µm and show that up to 17% of the total emission is fed into the TEM00 mode. Pulsed Hanbury-Brown Twiss (HBT) interferometry shows that an improvement in single photon purity is facilitated due to the increased spectral density.

4.
Opt Lett ; 42(7): 1297-1300, 2017 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-28362753

RESUMEN

Nanostructured and bulk silicon carbide (SiC) has recently emerged as a novel platform for quantum nanophotonics due to its harboring of paramagnetic color centers, having immediate applications as a single photon source and spin optical probes. Here, using ultra-short pulsed laser ablation, we fabricated from electron irradiated bulk 4H-SiC, 40-50 nm diameter SiC nanoparticles, fluorescent at 850-950 nm. This photoluminescence is attributed to the silicon vacancy color centers. We demonstrate that the original silicon vacancy color centers from the target sample were retained in the final nanoparticles solution, exhibiting excellent colloidal stability in water over several months. Our work is relevant for quantum nanophotonics, magnetic sensing, and biomedical imaging applications.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Rayos Láser , Microscopía Fluorescente/métodos , Nanopartículas/química , Compuestos de Silicona/química , Color
5.
Rep Prog Phys ; 80(3): 034502, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-28139468

RESUMEN

This paper summarizes key findings in single-photon generation from deep level defects in silicon carbide (SiC) and highlights the significance of these individually addressable centers for emerging quantum applications. Single photon emission from various defect centers in both bulk and nanostructured SiC are discussed as well as their formation and possible integration into optical and electrical devices. The related measurement protocols, the building blocks of quantum communication and computation network architectures in solid state systems, are also summarized. This includes experimental methodologies developed for spin control of different paramagnetic defects, including the measurement of spin coherence times. Well established doping, and micro- and nanofabrication procedures for SiC may allow the quantum properties of paramagnetic defects to be electrically and mechanically controlled efficiently. The integration of single defects into SiC devices is crucial for applications in quantum technologies and we will review progress in this direction.

6.
Nat Commun ; 6: 7783, 2015 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-26205309

RESUMEN

Electrically driven single-photon emitting devices have immediate applications in quantum cryptography, quantum computation and single-photon metrology. Mature device fabrication protocols and the recent observations of single defect systems with quantum functionalities make silicon carbide an ideal material to build such devices. Here, we demonstrate the fabrication of bright single-photon emitting diodes. The electrically driven emitters display fully polarized output, superior photon statistics (with a count rate of >300 kHz) and stability in both continuous and pulsed modes, all at room temperature. The atomic origin of the single-photon source is proposed. These results provide a foundation for the large scale integration of single-photon sources into a broad range of applications, such as quantum cryptography or linear optics quantum computing.

7.
Nat Mater ; 13(2): 151-6, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24240243

RESUMEN

Over the past few years, single-photon generation has been realized in numerous systems: single molecules, quantum dots, diamond colour centres and others. The generation and detection of single photons play a central role in the experimental foundation of quantum mechanics and measurement theory. An efficient and high-quality single-photon source is needed to implement quantum key distribution, quantum repeaters and photonic quantum information processing. Here we report the identification and formation of ultrabright, room-temperature, photostable single-photon sources in a device-friendly material, silicon carbide (SiC). The source is composed of an intrinsic defect, known as the carbon antisite-vacancy pair, created by carefully optimized electron irradiation and annealing of ultrapure SiC. An extreme brightness (2×10(6) counts s(-1)) resulting from polarization rules and a high quantum efficiency is obtained in the bulk without resorting to the use of a cavity or plasmonic structure. This may benefit future integrated quantum photonic devices.

8.
Phys Rev Lett ; 111(21): 213603, 2013 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-24313488

RESUMEN

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.

9.
Opt Lett ; 36(21): 4224-6, 2011 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-22048372

RESUMEN

We address for the first time the measurement of nonradiative decay rates in Cr-related centers in nanodiamonds. Compared to our previous quantum efficiency measurement of Cr centers created in bulk diamond, separate measurements of radiative and nonradiative decay rates in grown nanodiamonds prove more challenging due to size dependence effects. We demonstrate in this Letter that, using defocused dipole imaging and collection efficiency calculation via finite-difference time-domain (FDTD), a quantum efficiency up to 0.9 can be inferred to Cr-related centers showing a 2-level system photon statistics.

10.
Phys Rev Lett ; 105(21): 217403, 2010 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-21231353

RESUMEN

We present direct imaging of the emission pattern of individual chromium-based single photon emitters in diamond and measure their quantum efficiency. By imaging the excited state transition dipole intensity distribution in the back focal plane of high numerical aperture objective, we determined its 3D orientation. Employing ion implantation techniques, the emitters were placed at various distances from the diamond-air interface. By comparing the decay rates from the single chromium emitters at different depths in the diamond crystal, we measured an average quantum efficiency of 28%.

11.
Opt Express ; 13(18): 6709-22, 2005 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-19498688

RESUMEN

We describe an experiment in which photon pairs from a pulsed parametric down-conversion (PDC) source were coupled into single-mode fibers with heralding efficiencies as high as 70%. Heralding efficiency or mode preparation efficiency is defined as the probability of finding a photon in a fiber in a definite state, given the detection of its twin. Heralding efficiencies were obtained for a range of down-conversion beam-size configurations. Analysis of spatial and spectral mode selection, and their mutual correlation, provides a practical guide for engineering PDC-produced single photons in a definite mode and spectral emission band. The spectrum of the heralded photons were measured for each beam configuration, to determine the interplay between transverse momentum and spectral entanglement on the preparation efficiency.

12.
Phys Rev Lett ; 92(6): 060404, 2004 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-14995222

RESUMEN

We implemented the experiment proposed by Cabello in the preceding Letter to test the bounds of quantum correlation. As expected from the theory we found that, for certain choices of local observables, Tsirelson's bound of the Clauser-Horne-Shimony-Holt inequality (2 x square root of 2) is not reached by any quantum states.

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