Diamond chemical vapor deposition on optical fibers for fluorescence waveguiding

A technique has been developed for depositing diamond crystals on the endfaces of optical fibers and capturing the fluorescence generated by optically active defects in the diamond into the fiber. This letter details the diamond growth on optical fibers and transmission of fluorescence through the fiber from the nitrogen-vacancy (N-V) color center in diamond. Control of the concentration of defects incorporated during the chemical vapor deposition (CVD) growth process is also demonstrated. These are the first critical steps in developing a fiber coupled single photon source based on optically active defect centers in diamond.Comment: 10 pages, 3 figure

Imaging and quantum efficiency measurement of chromium emitters in diamond

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 that the emission dipole is oriented nearly orthogonal to the diamond-air interface. Employing ion implantation techniques, the emitters were engineered with various proximities from the diamond-air interface. By comparing the decay rates from the single chromium emitters at different depths in the diamond crystal, an average quantum efficiency of 28% was measured.Comment: 11 pages and 4 figure

Photophysics of chromium-related diamond single-photon emitters

A detailed study of the photophysical properties of several chromium-related color centers produced within chemical vapor deposition diamond is presented. These emitters show narrow luminescence lines in the range of 740-770nm. Single-photon emission was verified with continuous and pulsed excitation with detected emission rates at saturation in the range of (2-3)×106 counts/s, while direct lifetime measurements reveal excited state lifetimes for the distinct centers ranging 1-14 ns. In addition, a number of quantum emitters demonstrate two-level behavior with no bunching present in the second-order correlation function. The three-level systems revealed typically photoluminescence lines with width half-maximum of ~4nm while the two-level emitters have full width half-maximum of ~10nm at room temperature. In addition, the quantum efficiency of the two-level system was measured to be four times higher than that of the three-level syste

Reply on the comment on the paper "Superconducting transition in Nb nanowires fabricated using focused ion beam"

In this communication we present our response to the recent comment of A. Engel regarding our paper on FIB- fabricated Nb nanowires (see Vol. 20 (2009) Pag. 465302). After further analysis and additional experimental evidence, we conclude that our interpretation of the experimental results in light of QPS theory is still valid when compared with the alternative proximity-based model as proposed by A. Engel.Comment: 3 pages, 1 figure, accepted by Nanotechnolog

Phonon-induced dephasing of chromium colour centres in diamond

We report on the coherence properties of single photons from chromium-based colour centres in diamond. We use field-correlation and spectral lineshape measurements to reveal the interplay between slow spectral wandering and fast dephasing mechanisms as a function of temperature. We show that the zero-phonon transition frequency and its linewidth follow a power-law dependence on temperature indicating that the dominant fast dephasing mechanisms for these centres are direct electron-phonon coupling and phonon-modulated Coulomb coupling to nearby impurities. Further, the observed reduction in the quantum yield for photon emission as a function of temperature is consistent with the opening of additional nonradiative channels through thermal activation to higher energy states predominantly and indicates a near-unity quantum efficiency at 4 K

Single-photon emitting diode in silicon carbide

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 (SiC) 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.Comment: Main: 10 pages, 6 figures. Supplementary Information: 6 pages, 6 figure

Ion-beam modification of fullerene

The response of thin films of fullerene (C60) to energetic ion impact is investigated. The diagnostics employed include Fourier-transform infrared and Raman spectroscopies, cross-sectional transmission electron microscopy, and atomic force microscopy. By combining the information obtained from these diagnostics with that from the dependence of the conductivity on ion dose, it is concluded that each C60 molecule completely disintegrates when hit by an energetic ion. The cross section for the destruction is about 6×10-13 cm2 for irradiation with 620-keV Xe ions. The disintegration occurs when C atoms are knocked out of the molecule either directly by the impinging ion or by an energetic knock-on C atom within the damage cascade. This process is quite different from the Coulomb-explosion mechanism previously proposed in the literature. For very low ion doses