167 research outputs found
Collective Two-Atom Effects and Trapping States in the Micromaser
We investigate signals of trapping states in the micromaser system in terms
of the average number of cavity photons as well as a suitably defined
correlation length of atoms leaving the cavity. In the description of
collective two-atom effects we allow the mean number of pump atoms inside the
cavity during the characteristic atomic cavity transit time to be as large as
of order one. The master equation we consider, which describes the micromaser
including collective two-atom effects, still exhibits trapping states for even
for a mean number of atoms inside the cavity close to one. We, however, argue
more importantly that the trapping states are more pronounced in terms of the
correlation length as compared to the average number of cavity photons, i.e. we
suggest that trapping states can be more clearly revealed experimentally in
terms of the atom correlation length. For axion detection in the micromaser
this observable may therefore be an essential ingredient.Comment: 5 figure
Single microwave photon detection in the micromaser
High efficiency single photon detection is an interesting problem for many
areas of physics, including low temperature measurement, quantum information
science and particle physics. For optical photons, there are many examples of
devices capable of detecting single photons with high efficiency. However
reliable single photon detection of microwaves is very difficult, principally
due to their low energy. In this paper we present the theory of a cascade
amplifier operating in the microwave regime that has an optimal quantum
efficiency of 93%. The device uses a microwave photon to trigger the stimulated
emission of a sequence of atoms where the energy transition is readily
detectable. A detailed description of the detector's operation and some
discussion of the potential limitations of the detector are presented.Comment: 8 pages, 5 figure
Theory of spectroscopy in an optically pumped effusive vapor
We present a theoretical framework for studying spatially dependent absorption in a thermal vapor of multilevel atoms, of arbitrary optical thickness. The atomic state dynamics, governed by a standard atom-optical master equation, are self-consistently coupled to the axial evolution of the probe beam intensity and the effusive gas dynamics. We derive steady-state equations for the spatially varying distributions of atomic populations and the probe beam intensity. From the latter, absorption coefficients in both the saturated and unsaturated regimes can be calculated. We present solutions to the resulting equations at various levels of approximation, including an example of the full numerical solution of a saturated, optically thick vapor of three-level atoms, demonstrating a breakdown of Beer's law, among other measurable effects. © 2010 The American Physical Society
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
Absolute frequency measurements of 85Rb nF7/2 Rydberg states using purely optical detection
A three-step laser excitation scheme is used to make absolute frequency
measurements of highly excited nF7/2 Rydberg states in 85Rb for principal
quantum numbers n=33-100. This work demonstrates the first absolute frequency
measurements of rubidium Rydberg levels using a purely optical detection
scheme. The Rydberg states are excited in a heated Rb vapour cell and Doppler
free signals are detected via purely optical means. All of the frequency
measurements are made using a wavemeter which is calibrated against a GPS
disciplined self-referenced optical frequency comb. We find that the measured
levels have a very high frequency stability, and are especially robust to
electric fields. The apparatus has allowed measurements of the states to an
accuracy of 8.0MHz. The new measurements are analysed by extracting the
modified Rydberg-Ritz series parameters.Comment: 12 pages, 5 figures, submitted to New. J. Phy
Creating and observing N-partite entanglement with atoms
The Mermin inequality provides a criterion for experimentally ruling out
local-realistic descriptions of multiparticle systems. A violation of this
inequality means that the particles must be entangled, but does not, in
general, indicate whether N-partite entanglement is present. For this, a
stricter bound is required. Here we discuss this bound and use it to propose
two different schemes for demonstrating N-partite entanglement with atoms. The
first scheme involves Bose-Einstein condensates trapped in an optical lattice
and the second uses Rydberg atoms in microwave cavities.Comment: 12 pages, 4 figure
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