Wigner Molecules in Nanostructures

The one-- and two-- particle densities of up to four interacting electrons with spin, confined within a quasi one--dimensional ``quantum dot'' are calculated by numerical diagonalization. The transition from a dense homogeneous charge distribution to a dilute localized Wigner--type electron arrangement is investigated. The influence of the long range part of the Coulomb interaction is studied. When the interaction is exponentially cut off the ``crystallized'' Wigner molecule is destroyed in favor of an inhomogeneous charge distribution similar to a charge density wave .Comment: 10 pages (excl. Figures), Figures available on request LaTe

Radar and rocket comparison of UHF radar scattering from auroral electrojet irregularities: Implications for a nanosatellite radar

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95174/1/jgra19910.pd

Deterministic nano-assembly of a coupled quantum emitter - photonic crystal cavity system

The interaction of a single quantum emitter with its environment is a central theme in quantum optics. When placed in highly confined optical fields, such as those created in optical cavities or plasmonic structures, the optical properties of the emitter can change drastically. In particular, photonic crystal (PC) cavities show high quality factors combined with an extremely small mode volume. Efficiently coupling a single quantum emitter to a PC cavity is challenging because of the required positioning accuracy. Here, we demonstrate deterministic coupling of single Nitrogen-Vacancy (NV) centers to high-quality gallium phosphide PC cavities, by deterministically positioning their 50 nm-sized host nanocrystals into the cavity mode maximum with few-nanometer accuracy. The coupling results in a 25-fold enhancement of NV center emission at the cavity wavelength. With this technique, the NV center photoluminescence spectrum can be reshaped allowing for efficient generation of coherent photons, providing new opportunities for quantum science.Comment: 13 pages, 4 figure

Engineered arrays of NV color centers in diamond based on implantation of CN- molecules through nanoapertures

We report a versatile method to engineer arrays of nitrogen-vacancy (NV) color centers in dia- mond at the nanoscale. The defects were produced in parallel by ion implantation through 80 nm diameter apertures patterned using electron beam lithography in a PMMA layer deposited on a diamond surface. The implantation was performed with CN- molecules which increased the NV defect formation yield. This method could enable the realization of a solid-state coupled-spin array and could be used for positioning an optically active NV center on a photonic microstructure.Comment: 12 pages, 3 figure

Spin dynamics in the optical cycle of single nitrogen-vacancy centres in diamond

We investigate spin-dependent decay and intersystem crossing in the optical cycle of single negatively-charged nitrogen-vacancy (NV) centres in diamond. We use spin control and pulsed optical excitation to extract both the spin-resolved lifetimes of the excited states and the degree of optically-induced spin polarization. By optically exciting the centre with a series of picosecond pulses, we determine the spin-flip probabilities per optical cycle, as well as the spin-dependent probability for intersystem crossing. This information, together with the indepedently measured decay rate of singlet population provides a full description of spin dynamics in the optical cycle of NV centres. The temperature dependence of the singlet population decay rate provides information on the number of singlet states involved in the optical cycle.Comment: 11 pages, 5 figure

DISTO data on Kpp

The data from the DISTO Collaboration on the exclusive pp -> p K+ Lambda production acquired at T_p = 2.85 GeV have been re-analysed in order to search for a deeply bound K- pp (= X) state, to be formed in the binary process pp -> K+ X. The preliminary spectra of the DeltaM_{K+} missing-mass and of the M_{p Lambda} invariant-mass show, for large transverse-momenta of protons and kaons, a distinct broad peak with a mass M_X = 2265 +- 2 MeV/c^2 and a width Gamma_X = 118 +- 8 MeV/c^2.Comment: 8 pages, 4 figures. Talk presented at the "10th International Conference on Hypernuclear and Strange Particle Physics" (HYP-X), Tokai, Ibaraki, Japan, September 14th-18th, 2009. To appear in the proceeding

Proton Drip-Line Calculations and the Rp-process

One-proton and two-proton separation energies are calculated for proton-rich nuclei in the region $A=41-75$. The method is based on Skyrme Hartree-Fock calculations of Coulomb displacement energies of mirror nuclei in combination with the experimental masses of the neutron-rich nuclei. The implications for the proton drip line and the astrophysical rp-process are discussed. This is done within the framework of a detailed analysis of the sensitivity of rp process calculations in type I X-ray burst models on nuclear masses. We find that the remaining mass uncertainties, in particular for some nuclei with $N=Z$, still lead to large uncertainties in calculations of X-ray burst light curves. Further experimental or theoretical improvements of nuclear mass data are necessary before observed X-ray burst light curves can be used to obtain quantitative constraints on ignition conditions and neutron star properties. We identify a list of nuclei for which improved mass data would be most important.Comment: 20 pages, 9 figures, 2 table

High Energy Gamma Ray Production from Proton Induced Reactions on D, C, Zn, Pb at Incident Energies of 104, 145, and 195 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY-931478