437 research outputs found
Photon Bunching at TeV Energies
Harwit, Protheroe, and Biermann (1999) recently proposed that Bose-Einstein
photon bunching might significantly affect the interpretation of Cerenkov
counts of TeV gamma photons. Here, we show that a combination of two recent
results of Aharonian et al. (2000) and Aharonian et al. (2001) permits us to
set new, more stringent upper limits of on the fractional amount
of photon bunching in the 7-10 TeV radiation from Markarian 501. Potential
bunching at even higher energies should nevertheless continue to be
investigated for this and other TeV sources, since a clear understanding of TeV
energy spectra is required to unambiguously determine the spectral energy
density of the mid-infrared extragalactic background
Revisiting the Hanbury Brown-Twiss set-up for fractional statistics
The Hanbury Brown-Twiss experiment has proved to be an effective means of
probing statistics of particles. Here, in a set-up involving edge-state
quasiparticles in a fractional quantum Hall system, we show that a variant of
the experiment composed of two sources and two sinks can be used to unearth
fractional statistics. We find a clear cut signature of the statistics in the
equal-time current-current correlation function for quasiparticle currents
emerging from the two sources and collected at the sinks.Comment: 4 pages, 3 figure
Quantum atom optics with fermions from molecular dissociation
We study a fermionic atom optics counterpart of parametric down-conversion
with photons. This can be realized through dissociation of a Bose-Einstein
condensate of molecular dimers consisting of fermionic atoms. We present a
theoretical model describing the quantum dynamics of dissociation and find
analytic solutions for mode occupancies and atomic pair correlations, valid in
the short time limit. The solutions are used to identify upper bounds for the
correlation functions, which are applicable to any fermionic system and
correspond to ideal particle number-difference squeezingComment: Changes in response to referees' comments, updated reference
Exploring Lifetime Effects in Femtoscopy
We investigate the role of lifetime effects from resonances and emission
duration tails in femtoscopy at RHIC in two Blast-Wave models. We find the
non-Gaussian components compare well with published source imaged data, but the
value of R_out obtained from Gaussian fits is not insensitive to the
non-Gaussian contributions when realistic acceptance cuts are applied to
models.Comment: 5 pages, 2 figure
Rescattering Effects on Intensity Interferometry
We derive a general formula for the correlation function of two identical
particles with the inclusion of multiple elastic scatterings in the medium in
which the two particles are produced. This formula involves the propagator of
the particle in the medium. As illustration of the effect we apply the formula
to the special case where the scatterers are static, localized 2-body
potentials. In this illustration both and are
increased by an amount proportional to the square of the spatial density of
scatterers and to the differential cross section. Specific numbers are used to
show the expected magnitude of the rescattering effect on kaon interferometry.Comment: 15 pages, 4 figure
Multiparticle Interference, GHZ Entanglement, and Full Counting Statistics
We investigate the quantum transport in a generalized N-particle Hanbury
Brown--Twiss setup enclosing magnetic flux, and demonstrate that the Nth-order
cumulant of current cross correlations exhibits Aharonov-Bohm oscillations,
while there is no such oscillation in all the lower-order cumulants. The
multiparticle interference results from the orbital Greenberger-Horne-Zeilinger
entanglement of N indistinguishable particles. For sufficiently strong
Aharonov-Bohm oscillations the generalized Bell inequalities may be violated,
proving the N-particle quantum nonlocality.Comment: 4 pages, 1 figure, published versio
Transition from antibunching to bunching in cavity QED
The photon statistics of the light emitted from an atomic ensemble into a
single field mode of an optical cavity is investigated as a function of the
number of atoms. The light is produced in a Raman transition driven by a pump
laser and the cavity vacuum [M.Hennrich et al., Phys. Rev. Lett. 85, 4672
(2000)], and a recycling laser is employed to repeat this process continuously.
For weak driving, a smooth transition from antibunching to bunching is found
for about one intra-cavity atom. Remarkably, the bunching peak develops within
the antibunching dip. For saturated driving and a growing number of atoms, the
bunching amplitude decreases and the bunching duration increases, indicating
the onset of Raman lasing.Comment: 4 pages, 4 figure
Universal measurement of quantum correlations of radiation
A measurement technique is proposed which, in principle, allows one to
observe the general space-time correlation properties of a quantized radiation
field. Our method, called balanced homodyne correlation measurement, unifies
the advantages of balanced homodyne detection with those of homodyne
correlation measurements.Comment: 4 pages, 4 figures, small misprints were corrected, accepted to Phys.
Rev. Let
Instrumental and Analytic Methods for Bolometric Polarimetry
We discuss instrumental and analytic methods that have been developed for the
first generation of bolometric cosmic microwave background (CMB) polarimeters.
The design, characterization, and analysis of data obtained using Polarization
Sensitive Bolometers (PSBs) are described in detail. This is followed by a
brief study of the effect of various polarization modulation techniques on the
recovery of sky polarization from scanning polarimeter data. Having been
successfully implemented on the sub-orbital Boomerang experiment, PSBs are
currently operational in two terrestrial CMB polarization experiments (QUaD and
the Robinson Telescope). We investigate two approaches to the analysis of data
from these experiments, using realistic simulations of time ordered data to
illustrate the impact of instrumental effects on the fidelity of the recovered
polarization signal. We find that the analysis of difference time streams takes
full advantage of the high degree of common mode rejection afforded by the PSB
design. In addition to the observational efforts currently underway, this
discussion is directly applicable to the PSBs that constitute the polarized
capability of the Planck HFI instrument.Comment: 23 pages, 11 figures. for submission to A&
Small size boundary effects on two-pion interferometry
The Bose-Einstein correlations of two identically charged pions are derived
when these particles, the most abundantly produced in relativistic heavy ion
collisions, are confined in finite volumes. Boundary effects on single pion
spectrum are also studied. Numerical results emphasize that conventional
formulation usually adopted to describe two-pion interferometry should not be
used when the source size is small, since this is the most sensitive case to
boundary effects. Specific examples are considered for better illustration.Comment: more discussion on Figure4 and diffuse boundar
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