5,157 research outputs found
Few photon transport in a waveguide coupled to a pair of collocated two-level atoms
We calculate the one- and two-photon scattering matrices of a pair of
collocated non-identical two-level atoms coupled to a waveguide. We show that
by proper choice of a two-photon input, the background fluorescence by the
atoms may be completely quenched, as a result of quantum interference, and that
when the atoms' detuning is smaller than their linewidths, extremely narrow
fluorescence features emerge. Furthermore, the system emits a two-photon bound
state which can display spatial oscillations/quantum beats, and can be tuned
from bunched to anti-bunched statistics as the total photon energy is varied
Life History Characteristics Of Daphnia Lumholtzi And Its Susceptibility To An Invertebrate Predator
Is It Constitutional and Will It be Effective: An Analysis of Mandatory HIV Testing of Pregnant Women
Is It Constitutional and Will It be Effective: An Analysis of Mandatory HIV Testing of Pregnant Women
Microscopic model of diffusion limited aggregation and electrodeposition in the presence of levelling molecules
A microscopic model of the effect of unbinding in diffusion limited
aggregation based on a cellular automata approach is presented. The geometry
resembles electrochemical deposition - ``ions'' diffuse at random from the top
of a container until encountering a cluster in contact with the bottom, to
which they stick. The model exhibits dendritic (fractal) growth in the
diffusion limited case. The addition of a field eliminates the fractal nature
but the density remains low. The addition of molecules which unbind atoms from
the aggregate transforms the deposit to a 100% dense one (in 3D). The molecules
are remarkably adept at avoiding being trapped. This mimics the effect of
so-called ``leveller'' molecules which are used in electrochemical deposition
Trident pair production in strong laser pulses
We calculate the trident pair production amplitude in a strong laser
background. We allow for finite pulse duration, while still treating the laser
fields nonperturbatively in strong-field QED. Our approach reveals explicitly
the individual contributions of the one-step and two-step processes. We also
expose the role gauge invariance plays in the amplitudes and discuss the
relation between our results and the optical theorem.Comment: 4 pages, 1 .eps figure. Version 2: reference added, published versio
The box diagram in Yukawa theory
We present a light-front calculation of the box diagram in Yukawa theory. The
covariant box diagram is finite for the case of spin-1/2 constituents
exchanging spin-0 particles. In light-front dynamics, however, individual
time-ordered diagrams are divergent. We analyze the corresponding light-front
singularities and show the equivalence between the light-front and covariant
results by taming the singularities.Comment: 21 pages, 17 figures. submittes to Phys. Rev.
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