113,744 research outputs found
Entanglement in atomic resonance fluorescence
The resonance fluorescence from regular atomic systems is shown to represent
a continuous source of non-Gaussian entangled radiation propagating in two
different directions. For a single atom entanglement occurs under the same
conditions as squeezing. For more atoms, the entanglement can be more robust
against dephasing than squeezing, hence providing a useful continuous source
for various applications of entangled radiation.Comment: 4 pages, 1 figur
Multi-mode density matrices of light via amplitude and phase control
A new method is described for determining the quantum state of correlated
multimode radiation by interfering the modes and measuring the statistics of
the superimposed fields in four-port balanced homodyne detection. The full
information on the -mode quantum state is obtained by controlling both the
relative amplitudes and the phases of the modes, which simplifies the
reconstruction of density matrices to only Fourier transforms. In
particular, this method yields time-correlated multimode density matrices of
optical pulses by superimposing the signal by a sequence of short
local-oscillator pulses.Comment: 6 pages, late
Reconstructing and mesons from non-leptonic decays in C+C at 2AGeV
We predict transverse and longitudinal momentum spectra and yields of
and mesons reconstructed from hadron correlations in C+C
reactions at 2~AGeV. The rapidity and distributions for reconstructable
mesons differs strongly from the primary distribution, while the
's distributions are only weakly modified. We discuss the temporal and
spatial distributions of the particles emitted in the hadron channel. Finally,
we report on the mass shift of the due to its coupling to the
, which is observable in both the di-lepton and channel.
Our calculations can be tested with the Hades experiment at GSI, Darmstadt
Optimal Squeezing in Resonance Fluorescence via Atomic-State Purification
Squeezing of atomic resonance fluorescence is shown to be optimized by a
properly designed environment, which can be realized by a quasi-resonant
cavity. Optimal squeezing is achieved if the atomic coherence is maximized,
corresponding to a pure atomic quantum state. The atomic-state purification is
achieved by the backaction of the cavity field on the atom, which increases the
atomic coherence and decreases the atomic excitation. For realistic cavities,
the coupling of the atom to the cavity field yields a purity of the atomic
state of more than 99%. The fragility of squeezing against dephasing is
substantially reduced in this scenario, which may be important for various
applications.Comment: 6 pages including supplemental information, 3 figures. Accepted for
PR
Circular sets of primes of imaginary quadratic number fields
Let p be an odd prime number and let K be an imaginary
quadratic number field whose class number is not divisible by p. For a set S of primes of K whose norm is congruent to 1 modulo p, we introduce the notion of strict circularity. We show that if S is strictly circular, then the group G(KS(p)=K) is of cohomological dimension 2 and give some explicit examples
Free relative constructions in OT syntax
This paper is part of a research project on OT Syntax and the typology of the free relative (FR) construction. It concentrates on the details of an OT analysis and some of its consequences for OT syntax. I will not present a general discussion of the phenomenon and the many controversial issues it is famous for in generative syntax
Analysis of the antineutrino capture on protons
Corrections to the zeroth-approximation cross-section formula for antineutrino capture on protons at nuclear reactors are evaluated. They include recoil corrections 1/M of three kinds. The true recoil correction to the cross section is negligible. The weak-magnetism—axial-vector interference is sizable, decreasing the cross section by ∼2% for 5-MeV positrons. One also has to include the recoil-neutron energy in relating the positron and antineutrino energies in order to evaluate the antineutrino flux. That effect decreases the positron yield by as much as 6% for 5-MeV positrons. The radiative corrections of order α have been also evaluated; they increase the cross section by ∼1.5% near threshold and by ∼0.7% at 5MeV. Formulas and a table of numerical values of all corrections are presented
Neutrinoless double beta decay
The status of the search for neutrinoless double beta decay is reviewed. The
effort to reach the sensitivity needed to cover the effective Majorana neutrino
mass corresponding to the degenerate and inverted mass hierarchy is described.
Various issues concerning the theory (and phenomenology) of the relation
between the decay rate and the absolute neutrino mass scale
are discussed, in particular the issue of mechanism of the
decay. Finally, the relation between the neutrino magnetic moments and the
charge conjugation property (Dirac vs. Majorana) is described.Comment: Lecture notes at TASI2006, Boulder, CO, June 2006; to be published in
proceeding
A complete identification of lithium sites in a model of LiPO glass: effects of the local structure and energy landscape on ionic jump dynamics
We perform molecular dynamics simulations to study lithium dynamics in a
model of LiPO glass at temperatures below the glass transition. A
straightforward analysis of the ionic trajectories shows that lithium diffusion
results from jumps between sites that are basically unmodified on the time
scale of the lithium ionic relaxation. This allows us a detailed identification
and characterization of the sites. The results indicate that the number of
lithium sites is only slightly bigger than the number of lithium ions so that
the fraction of vacant sites is very limited at every instant. Mapping the
ionic trajectories onto series of jumps between the sites provides direct
access to lithium jump dynamics. For each site, we determine the mean residence
time and the probability that a jump from this site to another
site is followed by a direct backjump. While a broad distribution shows that different sites feature diverse lithium dynamics, high
values of give direct evidence for back-and-forth jumps. We further
study how the local glass structure and the local energy landscape affect
lithium jump dynamics. We observe substantial effects due to the energy
landscape, which are difficult to capture within single-particle approaches.Comment: 10 pages, 8 figure
Nuclear structure and double beta decay
Study of the neutrinoless double beta decay, , includes a
variety of problems of nuclear structure theory. They are reviewed here. The
problems range from the mechanism of the decay, i.e. exchange of the light
Majorana neutrino neutrino versus the exchange of some heavy, so far unobserved
particle. Next, the proper expressions for the corresponding operator are
described that should include the effects of the nucleon size and of the recoil
order terms in the hadronic current. The issue of proper treatment of the short
range correlations, in particular for the case of the heavy particle exchange,
is discussed also. The variety of methods employed these days in the
theoretical evaluation of the nuclear matrix elements is briefly
described and the difficulties causing the spread and hence uncertainty in the
values of are discussed. Finally, the issue of the axial current
quenching, and of the resonance enhancement in the case of double electron
capture are described.Comment: Review paper accepted for publication in the special issue of J.
Phys. G: Nucl. Phys. devoted to the double beta deca
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