P. Olivero

Coherent population trapping of single spins in diamond under optical excitation

Coherent population trapping is demonstrated in single nitrogen-vacancy centers in diamond under optical excitation. For sufficient excitation power, the fluorescence intensity drops almost to the background level when the laser modulation frequency matches the 2.88 GHz splitting of the ground states. The results are well described theoretically by a four-level model, allowing the relative transition strengths to be determined for individual centers. The results show that all-optical control of single spins is possible in diamond.

Fabrication of Ultrathin Single-Crystal Diamond Membranes†

A method for preparing ultrathin single-crystal diamond membranes suitable for post-processing and liftout, is reported. The proposed method used single-crystal diamond substrates and two-energy ion implant process for the fabrication of thin diamond membranes. Two ion-implant process was used in this method to prepare two different damage layers within diamond sample. This method can be used for preparing integrated quantum-photonic structure based on color center in diamond. This method can also be used for fabricating various structures including Bragg gratings and whispering gallery mode resonators. A significant application of the diamond nanostructures is to fabricate the micro- and nanoscale cantilevers. It was also observed that the fabricated single-crystal diamond are suitable for another FIB processing.

Characterization of three-dimensional microstructures in single-crystal diamond

We report on the Raman and photoluminescence characterization of three-dimensional microstructures fabricated in single crystal diamond with a Focused Ion Beam (FIB) assisted lift-off technique. The fabrication method is based on MeV ion implantation, followed by FIB micropatterning and selective chemical etching. In a previous publication we reported on the fabrication of a micro-bridge structure exhibiting waveguiding behavior [P. Olivero, S. Rubanov, P. Reichart, B. Gibson, S. Huntington, J. Rabeau, Andrew D. Greentree, J. Salzman, D. Moore, D. N. Jamieson, S. Prawer, Adv. Mater., 17 (20) (2005) 2427]. In the present work, Raman and photoluminescence spectroscopies are employed to characterize the structural quality of such microstructures, particularly as regards the removal of residual damage created during the machining process. Three-dimensional microstructures in high quality single crystal diamond have many applications, ranging from integrated quantum-optical devices to micro-electromechanical assemblies.

Micromachining structured optical fibers using focused ion beam milling

A focused ion beam is used to mill side holes in air-silica structured fibers. By way of example, side holes are introduced in two types of air-structured fiber, (1) a photonic crystal four-ring fiber and (2) a six-hole single-ring step-index structured fiber.

Coherent population trapping in diamond N-V centers at zero magnetic field.

All-optical coherent population trapping is possible in nitrogen-vacancy centers in diamond at zero magnetic field. This should allow for simpler implementations of potential devices involving optical manipulation of electron spins.

Critical components for diamond-based quantum coherent devices

The necessary elements for practical devices exploiting quantum coherence in diamond materials are summarized, and progress towards their realization documented. A brief review of future prospects for diamond-based devices is also provided.

Evidence of light guiding in ion-implanted diamond.

We demonstrate the feasibility of fabricating light-waveguiding microstructures in bulk single-crystal diamond by means of direct ion implantation with a scanning microbeam, resulting in the modulation of the refractive index of the ion-beam damaged crystal. Direct evidence of waveguiding through such buried microchannels is obtained with a phase-shift micro-interferometric method allowing the study of the multimodal structure of the propagating electromagnetic field. The possibility of defining optical and photonic structures by direct ion writing opens a range of new possibilities in the design of quantum-optical devices in bulk single-crystal diamond.

Fabrication and electrical characterization of three-dimensional graphitic microchannels in single crystal diamond

We report on the systematic characterization of conductive micro-channels fabricated in single-crystal diamond with direct ion microbeam writing. Focused high-energy ( MeV) helium ions are employed to selectively convert diamond with micrometric spatial accuracy to a stable graphitic phase upon thermal annealing, due to the induced structural damage occurring at the end-of-range. A variable-thickness mask allows the accurate modulation of the depth at which the microchannels are formed, from several µm deep up to the very surface of the sample. By means of cross-sectional transmission electron microscopy (TEM), we demonstrate that the technique allows the direct writing of amorphous (and graphitic, upon suitable thermal annealing) microstructures extending within the insulating diamond matrix in the three spatial directions, and in particular, that buried channels embedded in a highly insulating matrix emerge and electrically connect to the sample surface at specific locations. Moreover, by means of electrical characterization at both

Direct fabrication of three-dimensional buried conductive channels in single crystal diamond with ion microbeam induced graphitization

Abstract We report on a novel method for the fabrication of three-dimensional buried graphitic micropaths in single crystal diamond with the employment of focused MeV ions. The use of implantation masks with graded thickness at the sub-micrometer scale allows the formation of conductive channels which are embedded in the insulating matrix at controllable depths. In particular, the modulation of the channels depth at their endpoints allows the surface contacting of the channel terminations with no need of further fabrication stages. In the present work we describe the sample masking, which includes the deposition of semi-spherical gold contacts on the sample surface, followed by MeV ion implantation. Because of the significant difference between the densities of pristine and amorphous or graphitized diamond, the formation of buried channels has a relevant mechanical effect on the diamond structure, causing localized surface swelling, which has been measured both with interferometric profilometry and atomic force microscopy. The electrical properties of the buried channels are then measured with a two point probe station: clear evidence is given that only the terminal points of the channels are electrically connected with the surface, while the rest of the channels extends below the surface. IV measurements are employed also to qualitatively investigate the electrical properties of the channels as a function of implantation fluence and annealing.

Beating the Abbe diffraction limit in confocal microscopy via nonclassical photon statistics.

We experimentally demonstrate quantum enhanced resolution in confocal fluorescence microscopy exploiting the nonclassical photon statistics of single nitrogen-vacancy color centers in diamond. By developing a general model of superresolution based on the direct sampling of the kth-order autocorrelation function of the photoluminescence signal, we show the possibility to resolve, in principle, arbitrarily close emitting centers.