2,671 research outputs found
Dynamics of two atoms coupled to a cavity field
We investigate the interaction of two two-level atoms with a single mode
cavity field. One of the atoms is exactly at resonance with the field, while
the other is well far from resonance and hence is treated in the dispersive
limit. We find that the presence of the non-resonant atom produces a shift in
the Rabi frequency of the resonant atom, as if it was detuned from the field.
We focus on the discussion of the evolution of the state purity of each atom.Comment: LaTex, 2 figure
Modeling one-dimensional island growth with mass-dependent detachment rates
We study one-dimensional models of particle diffusion and
attachment/detachment from islands where the detachment rates gamma(m) of
particles at the cluster edges increase with cluster mass m. They are expected
to mimic the effects of lattice mismatch with the substrate and/or long-range
repulsive interactions that work against the formation of long islands.
Short-range attraction is represented by an overall factor epsilon<<1 in the
detachment rates relatively to isolated particle hopping rates [epsilon ~
exp(-E/T), with binding energy E and temperature T]. We consider various
gamma(m), from rapidly increasing forms such as gamma(m) ~ m to slowly
increasing ones, such as gamma(m) ~ [m/(m+1)]^b. A mapping onto a column
problem shows that these systems are zero-range processes, whose steady states
properties are exactly calculated under the assumption of independent column
heights in the Master equation. Simulation provides island size distributions
which confirm analytic reductions and are useful whenever the analytical tools
cannot provide results in closed form. The shape of island size distributions
can be changed from monomodal to monotonically decreasing by tuning the
temperature or changing the particle density rho. Small values of the scaling
variable X=epsilon^{-1}rho/(1-rho) favour the monotonically decreasing ones.
However, for large X, rapidly increasing gamma(m) lead to distributions with
peaks very close to and rapidly decreasing tails, while slowly increasing
gamma(m) provide peaks close to /2$ and fat right tails.Comment: 16 pages, 6 figure
Complications After Laparoscopic and Conventional Cholecystectomy: A Comparative Study
The growing popularity of laparoscopic cholecystectomy (LC) has made extensive series
comparing laparoscopic and conventional cholecystectomy in a prospective, randomized way
nearly impossible. To evaluate LC we compared retrospectively 800 laparoscopic with 748
conventional cholecystectomies (CC). Of the 800 LC, 10 (1.2%) were converted to laparotomy.
6 conversions were related to aberrant anatomical features or features making dissection very
difficult, 4 conversions were due to complications. There were 5 (0, 6%) intraoperative complications
during LC and 4 (0.5%) during CC. Postoperative morbidity was 2.1% (n = 17) after LC
and 3.7% (n = 28) after CC. Particularly the incidence of wound problems was only 0.5% (n = 4)
after LC while it was 1.3% (n = 10) after CC. Overall morbidity was 2.7% (n = 22) for LC and
4.2% (n = 32) for CC. Mortality rate after CC was 0.4% (n = 3), there were no deaths after LC.
Common bile duct-injury rate was 0.2% (n = 2) for both groups. Complication rates after LC
have been rapidly decreasing with growing experience. Laparoscopic cholecystectomy can safely
be performed by appropriately trained surgeons in more than 90% of patients suffering from
gallbladder disease. The low morbidity and mortality together with the significant advantages to
patient recovery makes laparoscopic cholecystectomy the treatment of choice for symptomatic
cholecystolithiasis
Quantum bit detector
We propose and analyze an experimental scheme of quantum nondemolition
detection of monophotonic and vacuum states in a superconductive toroidal
cavity by means of Rydberg atoms.Comment: 4 pages, 3 figure
Generating and probing a two-photon Fock state with a single atom in a cavity
A two-photon Fock state is prepared in a cavity sustaining a "source mode "
and a "target mode", with a single circular Rydberg atom. In a third-order
Raman process, the atom emits a photon in the target while scattering one
photon from the source into the target. The final two-photon state is probed by
measuring by Ramsey interferometry the cavity light shifts induced by the
target field on the same atom. Extensions to other multi-photon processes and
to a new type of micromaser are briefly discussed
Test of quantum nonlocality for cavity fields
There have been studies on formation of quantum-nonlocal states in spatially
separate two cavities. We suggest a nonlocal test for the field prepared in the
two cavities. We couple classical driving fields with the cavities where a
nonlocal state is prepared. Two independent two-level atoms are then sent
through respective cavities to interact off-resonantly with the cavity fields.
The atomic states are measured after the interaction. Bell's inequality can be
tested by the joint probabilities of two-level atoms being in their excited or
ground states. We find that quantum nonlocality can also be tested using a
single atom sequentially interacting with the two cavities. Potential
experimental errors are also considered. We show that with the present
experimental condition of 5% error in the atomic velocity distribution, the
violation of Bell's inequality can be measured.Comment: 14pages, 2figures. accepted to Phys. Rev.
Reply to Comment by J. Zhang and N. Makris on “Estimates of the Ground Accelerations at Point Reyes Station during the 1906 San Francisco Earthquake” by A. Anooshehpoor, T. H. Heaton, B. Shi, and J. N. Brune
Contrary to the comments by Zhang and Makris (hereafter, ZM), our equations of motion governing the rocking response of a rectangular block subjected to a full-sine acceleration pulse are correct. Therefore, the first part of ZM's discussion, which is based primarily upon the assumption that the equations of motion in our article were incorrect, is inappropriate. In the second part of the discussion, ZM present new results for mode 2, toppling without impact. We did not consider this mode because it was not relevant to the Point Reyes train, which by eyewitness accounts, had overturned after experiencing one impact. However, as explained in this reply, toppling with no impact is never the minimum condition for overturning, and would in general involve very large horizontal accelerations, especially at frequencies where mode 2 is the only overturning mode
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