12 research outputs found
General boundary conditions for the envelope function in multiband k.p model
We have derived general boundary conditions (BC) for the multiband envelope
functions (which do not contain spurious solutions) in semiconductor
heterostructures with abrupt heterointerfaces. These BC require the
conservation of the probability flux density normal to the interface and
guarantee that the multiband Hamiltonian be self--adjoint. The BC are energy
independent and are characteristic properties of the interface. Calculations
have been performed of the effect of the general BC on the electron energy
levels in a potential well with infinite potential barriers using a coupled two
band model. The connection with other approaches to determining BC for the
envelope function and to the spurious solution problem in the multiband k.p
model are discussed.Comment: 15 pages, 2 figures; to be published in Phys. Rev. B 65, March 15
issue 200
Quantum radiation pressure on a moving mirror at finite temperature
We compute the radiation pressure force on a moving mirror, in the
nonrelativistic approximation, assuming the field to be at temperature At
high temperature, the force has a dissipative component proportional to the
mirror velocity, which results from Doppler shift of the reflected thermal
photons. In the case of a scalar field, the force has also a dispersive
component associated to a mass correction. In the electromagnetic case, the
separate contributions to the mass correction from the two polarizations
cancel. We also derive explicit results in the low temperature regime, and
present numerical results for the general case. As an application, we compute
the dissipation and decoherence rates for a mirror in a harmonic potential
well.Comment: Figure 3 replaced, changes mainly in Sections IV and V, new appendix
introduced. To appear in Physical Review
New Upper Limit of Terrestrial Equivalence Principle Test for Rotating Extended Bodies
Improved terrestrial experiment to test the equivalence principle for
rotating extended bodies is presented, and a new upper limit for the violation
of the equivalence principle is obtained at the level of 1.6, which is limited by the friction of the rotating gyroscope. It
means the spin-gravity interaction between the extended bodies has not been
observed at this level.Comment: 4 page
Effect of the Surface on the Electron Quantum Size Levels and Electron g-Factor in Spherical Semiconductor Nanocrystals
The structure of the electron quantum size levels in spherical nanocrystals
is studied in the framework of an eight--band effective mass model at zero and
weak magnetic fields. The effect of the nanocrystal surface is modeled through
the boundary condition imposed on the envelope wave function at the surface. We
show that the spin--orbit splitting of the valence band leads to the
surface--induced spin--orbit splitting of the excited conduction band states
and to the additional surface--induced magnetic moment for electrons in bare
nanocrystals. This additional magnetic moment manifests itself in a nonzero
surface contribution to the linear Zeeman splitting of all quantum size energy
levels including the ground 1S electron state. The fitting of the size
dependence of the ground state electron g factor in CdSe nanocrystals has
allowed us to determine the appropriate surface parameter of the boundary
conditions. The structure of the excited electron states is considered in the
limits of weak and strong magnetic fields.Comment: 11 pages, 4 figures, submitted to Phys. Rev.
Comparison of advanced gravitational-wave detectors
We compare two advanced designs for gravitational-wave antennas in terms of
their ability to detect two possible gravitational wave sources. Spherical,
resonant mass antennas and interferometers incorporating resonant sideband
extraction (RSE) were modeled using experimentally measurable parameters. The
signal-to-noise ratio of each detector for a binary neutron star system and a
rapidly rotating stellar core were calculated. For a range of plausible
parameters we found that the advanced LIGO interferometer incorporating RSE
gave higher signal-to-noise ratios than a spherical detector resonant at the
same frequency for both sources. Spheres were found to be sensitive to these
sources at distances beyond our galaxy. Interferometers were sensitive to these
sources at far enough distances that several events per year would be expected
Detector Description and Performance for the First Coincidence Observations between LIGO and GEO
For 17 days in August and September 2002, the LIGO and GEO interferometer
gravitational wave detectors were operated in coincidence to produce their
first data for scientific analysis. Although the detectors were still far from
their design sensitivity levels, the data can be used to place better upper
limits on the flux of gravitational waves incident on the earth than previous
direct measurements. This paper describes the instruments and the data in some
detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial
change
Analysis of LIGO data for gravitational waves from binary neutron stars
We report on a search for gravitational waves from coalescing compact binary
systems in the Milky Way and the Magellanic Clouds. The analysis uses data
taken by two of the three LIGO interferometers during the first LIGO science
run and illustrates a method of setting upper limits on inspiral event rates
using interferometer data. The analysis pipeline is described with particular
attention to data selection and coincidence between the two interferometers. We
establish an observational upper limit of 1.7 \times 10^{2}M_\odot$.Comment: 17 pages, 9 figure