4,265 research outputs found
Tables of two-sided tolerance factors for normal distributions
Tables of two-sided tolerance factors for normal distribution
A Technique to Derive Improved Proper Motions for Kepler Objects of Interest
We outline an approach yielding proper motions with higher precision than
exists in present catalogs for a sample of stars in the Kepler field. To
increase proper motion precision we combine first moment centroids of Kepler
pixel data from a single Season with existing catalog positions and proper
motions. We use this astrometry to produce improved reduced proper motion
diagrams, analogous to a Hertzsprung-Russell diagram, for stars identified as
Kepler Objects of Interest. The more precise the relative proper motions, the
better the discrimination between stellar luminosity classes. With UCAC4 and
PPMXL epoch 2000 positions (and proper motions from those catalogs as
quasi-bayesian priors) astrometry for a single test Channel (21) and Season (0)
spanning two years yields proper motions with an average per-coordinate proper
motion error of 1.0 millisecond of arc per year, over a factor of three better
than existing catalogs. We apply a mapping between a reduced proper motion
diagram and an HR diagram, both constructed using HST parallaxes and proper
motions, to estimate Kepler Object of Interest K-band absolute magnitudes. The
techniques discussed apply to any future small-field astrometry as well as the
rest of the Kepler field.Comment: Accepted to The Astronomical Journal 15 August 201
Passage-time statistics of superradiant light pulses from Bose-Einstein condensates
We discuss the passage-time statistics of superradiant light pulses generated
during the scattering of laser light from an elongated atomic Bose-Einstein
condensate. Focusing on the early-stage of the phenomenon, we analyze the
corresponding probability distributions and their scaling behaviour with
respect to the threshold photon number and the coupling strength. With respect
to these parameters, we find quantities which only vary significantly during
the transition between the Kapitza Dirac and the Bragg regimes. A possible
connection of the present observations to Brownian motion is also discussed.Comment: Close to the version published in J. Phys.
Quantum interference initiated super- and subradiant emission from entangled atoms
We calculate the radiative characteristics of emission from a system of
entangled atoms which can have a relative distance larger than the emission
wavelength. We develop a quantum multipath interference approach which explains
both super- and subradiance though the entangled states have zero dipole
moment. We derive a formula for the radiated intensity in terms of different
interfering pathways. We further show how the interferences lead to directional
emission from atoms prepared in symmetric W-states. As a byproduct of our work
we show how Dicke's classic result can be understood in terms of interfering
pathways. In contrast to the previous works on ensembles of atoms, we focus on
finite numbers of atoms prepared in well characterized states.Comment: 10 pages, 8 figures, 2 Table
Coherent control of collective spontaneous emission in an extended atomic ensemble and quantum storage
Coherent control of collective spontaneous emission in an extended atomic
ensemble resonantly interacting with single-photon wave packets is analyzed. A
scheme for coherent manipulation of collective atomic states is developed such
that superradiant states of the atomic system can be converted into subradiant
ones and vice versa. Possible applications of such a scheme for optical quantum
state storage and single-photon wave packet shaping are discussed. It is shown
that also in the absence of inhomogeneous broadening of the resonant line,
single-photon wave packets with arbitrary pulse shape may be recorded as a
subradiant state and reconstructed even although the duration of the wave
packets is larger than the superradiant life-time. Specifically the
applicability for storing time-bin qubits, which are used in quantum
cryptography is analyzed.Comment: 11 pages, 4 figures, submitted to PR
Excitonic Effects and Optical Spectra of Single-Walled Carbon Nanotubes
Many-electron effects often dramatically modify the properties of reduced
dimensional systems. We report calculations, based on an many-electron Green's
function approach, of electron-hole interaction effects on the optical spectra
of small-diameter single-walled carbon nanotubes. Excitonic effects
qualitatively alter the optical spectra of both semiconducting and metallic
tubes. Excitons are bound by ~ 1 eV in the semiconducting (8,0) tube and by ~
100 meV in the metallic (3,3) tube. These large many-electron effects explain
the discrepancies between previous theories and experiments.Comment: 6 pages, 3 figures, 2 table
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