3,784 research outputs found
Photon noise in a random laser amplifier with fluctuating properties
We study fluctuations of the number of photocounts measured by an ideal
photodetector illuminated by light scattered in an amplifying disordered
medium, below the threshold for random lasing. We show that the variance of
fluctuations and their correlation function carry information about fluctuating
properties of the medium. A direct link is established between the fluctuations
of the number of photocounts due to the amplified spontaneous emission (ASE)
and the dimensionless conductance g of the medium. Our results suggest a
possibility of probing amplifying disordered media by analyzing statistics of
their ASE, without illuminating them from outside by a probe beam.Comment: 14 pages, 9 figure
Square-well solution to the three-body problem
The angular part of the Faddeev equations is solved analytically for s-states
for two-body square-well potentials. The results are, still analytically,
generalized to arbitrary short-range potentials for both small and large
distances. We consider systems with three identical bosons, three non-identical
particles and two identical spin-1/2 fermions plus a third particle with
arbitrary spin. The angular wave functions are in general linear combinations
of trigonometric and exponential functions. The Efimov conditions are obtained
at large distances. General properties and applications to arbitrary potentials
are discussed. Gaussian potentials are used for illustrations. The results are
useful for numerical calculations, where for example large distances can be
treated analytically and matched to the numerical solutions at smaller
distances. The saving is substantial.Comment: 34 pages, LaTeX file, 9 postscript figures included using epsf.st
Efimov effect in nuclear three-body resonance decays
We investigate the effects of the nearly fulfilled Efimov conditions on the
properties of three-body resonances. Using the hyper-spheric adiabatic
expansion method we compute energy distributions of fragments in a three-body
decay of a nuclear resonance. As a realistic example we investigate the 1-
state in the halo nucleus 11Li within a three-body 9Li+n+n model.
Characteristic features appear as sharp peaks in the energy distributions.
Their origin, as in the Efimov effect, is in the large two-body s-wave
scattering lengths between the pairs of fragments
Complex scaling of the hyper-spheric coordinates and Faddeev equations
We implement complex scaling of Faddeev equations using hyper-spheric
coordinates and adiabatic expansion. Complex scaling of coordinates allows
convenient calculations of three-body resonances. We derive the necessary
equations and investigate the adiabatic spectrum at large distances. We
illustrate the viability of the implementation by calculations of several
three-body resonances: a resonance in a model benchmark system of three
identical bosons; the resonance in the He nucleus within the
model; and the two resonances in C within the
three- model.Comment: 20 pages, 10 figure
- …