Dissipation of System and Atom in Two-Photon Jaynes–Cummings Model with Degenerate Atomic Levels

A method of perturbative expansion of master equation is employed to study the dissipative properties of system and of atom in the two-photon Jaynes–Cummings model (JCM) with degenerate atomic levels. The numerical results show that the degeneracy of atomic levels prolongs the period of entanglement between the atom and the field. The asymptotic value of atomic linear entropy is apparently increased by the degeneration. The amplitude of local entanglement and disentanglement is suppressed. The better the initial coherence property of the degenerate atom, the larger the coherence loss.     

Compensation for pixel-mismatch errors in shift-multiplexed holographic data storage

To read out correct data from shift-multiplexed holographic data storage, we propose a novel method of pixel matching by use of a tiny plane-parallel refraction plate placed in the path of converging readout beams. Tilting the refraction plate produces a shift in the lateral position of the readout beam incident upon the holographic storage disk, leading to compensation for pixel-mismatch errors by an improvement in bit-error rate of 3 orders of magnitude.     

Long optically controlled delays in optical fibers

Optically controlled delay lines in optical fibers are demonstrated by use of the group-velocity control of signal pulses based on stimulated Brillouin scattering. We achieve continuous time delay within the range of 150 ns, much larger than the width of the 40 ns signal pulse, using cascaded fiber segments joined by unidirectional optical attenuators. In the meantime, we also observe a large amount of pulse broadening, which agrees well with a theoretical prediction based on linear theory.     

Performance analysis of very-small-aperture lasers

The fabrication of very-small-aperture lasers is demonstrated, and their performance is analyzed. Because of strong optical feedback caused by a gold film on the front facet of the laser, its behavior changes: The threshold current decreases, the density of light inside the laser diode and the redshift effect of the spectra are enhanced, and the laser diode's lifetime is shorter than that of common laser diodes with large driving current.     

Time-of-flight flow imaging using NMR remote detection

A time-of-flight imaging technique is introduced to visualize fluid flow and dispersion through porous media using NMR. As the fluid flows through a sample, the nuclear spin magnetization is modulated by rf pulses and magnetic field gradients to encode the spatial coordinates of the fluid. When the fluid leaves the sample, its magnetization is recorded by a second rf coil. This scheme not only facilitates a time-dependent imaging of fluid flow, it also allows a separate optimization of encoding and detection subsystems to enhance overall sensitivity. The technique is demonstrated by imaging gas flow through a porous rock.     

Synthesis of peptide-nanotube platinum-nanoparticle composites

Nanotubes prepared by the self-assembly of D-Phe-D-Phe molecules are investigated by electron microscopy and Monte Carlo simulations; the nanotubes appear to be porous and are capable of forming novel peptide-nanotube platinum-nanoparticle composites.     

Assay of histamine by nano-liquid chromatography/tandem mass spectrometry with a packed nanoelectrospray emitter

A nano-liquid chromatographic /tandem mass spectrometric (nanoHPLC/MS/MS) method has been developed for the sensitive determination of histamine, a vital neurotransmitter. The method involved pre-column derivatization of histamine with 7-fluoro-4-nitrobenzoxadiazole (NBD-F), thus increasing the hydrophobicity of the analyte and allowing it to be retained and stacked on a nanoelectrospay emitter packed with C18 reversed-phase particles. Sodium 1-heptanesulfonate, added as an ion-pairing reagent in the mobile phase for sample loading, was found to facilitate greatly the analyte retention. The packed nanoelectrospray emitter was easily prepared using fused-silica capillary of 75 microm i.d., and included creating an electrospray emitter tip and then slurry-packing a 5 cm long column with 5 microm silica-based particles. After sample loading, the mobile phase was changed for separation and a characteristic precursor-to-product ion transition, m/z 275 --> 258, was used for the quantification. A linear calibration curve in the range from 1.0-100 ng/mL histamine with an r2 value of 0.9995 was obtained. The detection limit was estimated to be 0.1 ng/mL histamine in water. In a preliminary validation, the method was applied to determine histamine in alcoholic beverages and rat brain tissues.     

Spectroscopic Study on the Photophysical Properties of Lanthanide Complexes with 2, 2′-Bipyridine-N, N′-dioxide

Five novel lanthanide (Eu3+, Tb3+, Gd3+, Sm3+ and Dy3+) complexes with 2, 2'-bipyridine-N, N'-dioxide (bipyO2) were synthesized and characterized by elemental analysis, IR spectrum. The triplet state energy of bipy O2 was determined to be 22275 cm(-1) with the phosphorescence spectrum of bipy O2 and its gadolinium complex. The photophysical properties of these complexes indicated that the triplet state energy of the ligand is suitable for the sensitization of the luminescence of Eu3+, Tb3+, Sm3+ and Dy3+, especially of Tb3+.