We describe how a quantum non-demolition device based on electromagnetically-induced transparency in solidstate atom-like systems could be realized. Such a resource, requiring only weak optical nonlinearities, could potentially enable photonic quantum information processing (QIP) that is much more efficient than QIP based on linear optics alone. As an example, we show how a parity gate could be constructed. A particularly interesting physical system for constructing devices is the nitrogen-vacancy defect in diamond, but the excited-state structure for this system is unclear in the existing literature. We include some of our latest spectroscopic results that indicate that the optical transitions are generally not spin-preserving, even at zero magnetic field, which allows the realization of a Λ-type system.
In the last decade, the synthesis and characterization of nanometer sized carbon clusters have attracted growing interest within the scientific community. This is due to both scientific interest in the process of diamond nucleation and growth, and to the promising technological applications in nanoelectronics and quantum communications and computing. Our research group has demonstrated that MeV carbon ion implantation in fused silica followed by thermal annealing in the presence of hydrogen leads to the formation of nanocrystalline diamond, with cluster size ranging from 5 to 40 nm. In the present paper, we report the synthesis of carbon nanoclusters by the implantation into fused silica of keV carbon ions using the Plasma Immersion Ion Implantation (PIII) technique, followed by thermal annealing in forming gas (4% 2H in Ar). The present study is aimed at evaluating this implantation technique that has the advantage of allowing high fluence-rates on large substrates. The carbon nanostructures have been characterized with optical absorption and Raman spectroscopies, cross sectional Transmission Electron Microscopy (TEM), and Parallel Electron Energy Loss Spectroscopy (PEELS). Nuclear Reaction Analysis (NRA) has been employed to evaluate the deuterium incorporation during the annealing process, as a key mechanism to stabilize the formation of the clusters.
Although sub-micron structures have been fabricated with ion beam lithography using focused MeV ions, the best resolution of the method has not yet been approached. The best resolution is potentially around 10 nm which is the diameter of latent damage produced by the passage of a single fast ion through sensitive materials where the ion range could be tens of micrometres. In principle, the latent damage can be developed to create very high aspect ratio nanostructures. We call this technique single ion nanolithography. In order to approach the ultimate resolution of lithography with single ions we investigate the resist material, the exposure as a function of ion type and development parameters. To implement the technique we have developed a novel strategy that employs a resist film on an active substrate that functions as a detector sensitive to single ion impacts. Together with a focused microbeam, the precise control of ion fluence attained by counting ion impacts allows us to perform a convenient systematic study of the track formation and seek conditions where single ion tracks can be produced. We report here the current status of the investigations using PMMA and CR-39 resists which are shown to be sensitive to single ions. A key issue is also the post-development imaging method.