302 research outputs found
Ensemble versus individual system in quantum optics
Modern techniques allow experiments on a single atom or system, with new
phenomena and new challenges for the theoretician. We discuss what quantum
mechanics has to say about a single system. The quantum jump approach as well
as the role of quantum trajectories are outlined and a rather sophisticated
example is given.Comment: Fundamental problems in quantum theory workshop, invited lecture. 11
pages Latex + 7 figures. To appear in Fortschr. d. Physi
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
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
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