22,248 research outputs found
Detection and control of individual nuclear spins using a weakly coupled electron spin
We experimentally isolate, characterize and coherently control up to six
individual nuclear spins that are weakly coupled to an electron spin in
diamond. Our method employs multi-pulse sequences on the electron spin that
resonantly amplify the interaction with a selected nuclear spin and at the same
time dynamically suppress decoherence caused by the rest of the spin bath. We
are able to address nuclear spins with interaction strengths that are an order
of magnitude smaller than the electron spin dephasing rate. Our results provide
a route towards tomography with single-nuclear-spin sensitivity and greatly
extend the number of available quantum bits for quantum information processing
in diamond
Basic linear algebra subprograms for FORTRAN usage
A package of 38 low level subprograms for many of the basic operations of numerical linear algebra is presented. The package is intended to be used with FORTRAN. The operations in the package are dot products, elementary vector operations, Givens transformations, vector copy and swap, vector norms, vector scaling, and the indices of components of largest magnitude. The subprograms and a test driver are available in portable FORTRAN. Versions of the subprograms are also provided in assembly language for the IBM 360/67, the CDC 6600 and CDC 7600, and the Univac 1108
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
Spotting the diffusion of New Psychoactive Substances over the Internet
Online availability and diffusion of New Psychoactive Substances (NPS)
represent an emerging threat to healthcare systems. In this work, we analyse
drugs forums, online shops, and Twitter. By mining the data from these sources,
it is possible to understand the dynamics of drugs diffusion and their
endorsement, as well as timely detecting new substances. We propose a set of
visual analytics tools to support analysts in tackling NPS spreading and
provide a better insight about drugs market and analysis
Ultra-fine beryllium powder by amalgam process Progress report, period ending 31 Oct. 1966
Metallurgical evaluation of beryllium powdered metal, and electron microscope studies of agglomerate particle size
Path Integral Approach to Residual Gauge Fixing
In this paper we study the question of residual gauge fixing in the path
integral approach for a general class of axial-type gauges including the
light-cone gauge. We show that the two cases -- axial-type gauges and the
light-cone gauge -- lead to very different structures for the explicit forms of
the propagator. In the case of the axial-type gauges, fixing the residual
symmetry determines the propagator of the theory completely. On the other hand,
in the light-cone gauge there is still a prescription dependence even after
fixing the residual gauge symmetry, which is related to the existence of an
underlying global symmetry.Comment: revtex 13pages, slightly expanded discussion, version to be published
in Physical Review
Evaluation of the application of ERTS-1 data to the regional land use planning process
The author has identified the following significant results. Employing simple and economical extraction methods, ERTS can provide valuable data to the planners at the state or regional level with a frequency never before possible. Interactive computer methods of working directly with ERTS digital information show much promise for providing land use information at a more specific level, since the data format production rate of ERTS justifies improved methods of analysis
Probing dynamics of an electron-spin ensemble via a superconducting resonator
We study spin relaxation and diffusion in an electron-spin ensemble of
nitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing
magnetic field (80-300 mT). Measurements exploit mode- and
temperature-dependent coupling of hyperfine-split sub-ensembles to the
resonator. Temperature-independent spin linewidth and relaxation time suggest
that spin diffusion limits spin relaxation. Depolarization of one sub-ensemble
by resonant pumping of another indicates fast cross-relaxation compared to spin
diffusion, with implications on use of sub-ensembles as independent quantum
memories.Comment: 5 pages, 5 figures, and Supplementary Information (2 figures
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