65,600 research outputs found
Resolving single molecule structures with Nitrogen-vacancy centers in diamond.
We present theoretical proposals for two-dimensional nuclear magnetic resonance spectroscopy protocols based on Nitrogen-vacancy (NV) centers in diamond that are strongly coupled to the target nuclei. Continuous microwave and radio-frequency driving fields together with magnetic field gradients achieve Hartmann-Hahn resonances between NV spin sensor and selected nuclei for control of nuclear spins and subsequent measurement of their polarization dynamics. The strong coupling between the NV sensor and the nuclei facilitates coherence control of nuclear spins and relaxes the requirement of nuclear spin polarization to achieve strong signals and therefore reduced measurement times. Additionally, we employ a singular value thresholding matrix completion algorithm to further reduce the amount of data required to permit the identification of key features in the spectra of strongly sub-sampled data. We illustrate the potential of this combined approach by applying the protocol to a shallowly implanted NV center addressing a small amino acid, alanine, to target specific hydrogen nuclei and to identify the corresponding peaks in their spectra
Null particle solutions in three-dimensional (anti-) de Sitter spaces
We obtain a class of exact solutions representing null particles moving in
three-dimensional (anti-) de Sitter spaces by boosting the corresponding static
point source solutions given by Deser and Jackiw. In de Sitter space the
resulting solution describes two null particles moving on the (circular)
cosmological horizon, while in anti-de Sitter space it describes a single null
particle propagating from one side of the universe to the other. We also boost
the BTZ black hole solution to the ultrarelativistic limit and obtain the
solution for a spinning null particle moving in anti-de Sitter space. We find
that the ultrarelativistic geometry of the black hole is exactly the same as
that resulting from boosting the Deser-Jackiw solution when the angular
momentum of the hole vanishes. A general class of solutions is also obtained
which represents several null particles propagating in the Deser-Jackiw
background. The differences between the three-dimensional and four-dimensional
cases are also discussed.Comment: 11 pages, LaTeX, To appear in J. Math. Phy
The Cardy-Verlinde Formula and Charged Topological AdS Black Holes
We consider the brane universe in the bulk background of the charged
topological AdS black holes. The evolution of the brane universe is described
by the Friedmann equations for a flat or an open FRW-universe containing
radiation and stiff matter. We find that the temperature and entropy of the
dual CFT are simply expressed in terms of the Hubble parameter and its time
derivative, and the Friedmann equations coincide with thermodynamic formulas of
the dual CFT at the moment when the brane crosses the black hole horizon. We
obtain the generalized Cardy-Verlinde formula for the CFT with an R-charge, for
any values of the curvature parameter k in the Friedmann equations.Comment: 10 pages, LaTeX, references adde
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