4,297 research outputs found
Entangled and disentangled evolution for a single atom in a driven cavity
For an atom in an externally driven cavity, we show that special initial
states lead to near-disentangled atom-field evolution, and superpositions of
these can lead to near maximally-entangled states. Somewhat counterintutively,
we find that (moderate) spontaneous emission in this system actually leads to a
transient increase in entanglement beyond the steady-state value. We also show
that a particular field correlation function could be used, in an experimental
setting, to track the time evolution of this entanglement
Non-Hermitian description of a superconducting phase qubit measurement
We present an approach based on a non-Hermitian Hamiltonian to describe the
process of measurement by tunneling of a phase qubit state. We derive simple
analytical expressions which describe the dynamics of measurement, and compare
our results with those experimentally available.Comment: 8 pages, 4 figure
Measured Quantum Dynamics of a Trapped Ion
The measurement process is taken into account in the dynamics of trapped ions
prepared in nonclassical motional states. The induced decoherence is shown to
manifest itself both in the inhibition of the internal population dynamics and
in a damping of the vibrational motion without classical counterpart.
Quantitative comparison with present experimental capabilities is discussed,
leading to a proposal for the verification of the predicted effects.Comment: 5 Pages, no figures; Plain REVTeX; to be published in the 1st May
issue of Phys. Rev. A, Rap. Commun. (1997
Petrographic and crystallographic study of silicate minerals in lunar rocks
Optical U-stage measurements, chemical microprobe data, and X-ray procession photographs of a bytownite twin group from rock 12032,44 are compared. Sharp but weak b and no c-reflections were observed for this An89 bytownite indicating a partly disordered structure. Euler angles, used to characterize the orientation of the optical indicatrix, compare better with values for plutonic than for volcanic plagioclase. This indicates that structural and optical properties cannot be directly correlated
An open systems approach to calculating time dependent spectra
A new method to calculate the spectrum using cascaded open systems and master
equations is presented. The method uses two state analyzer atoms which are
coupled to the system of interest, whose spectrum of radiation is read from the
excitation of these analyzer atoms. The ordinary definitions of a spectrum uses
two-time averages and Fourier-transforms. The present method uses only one-time
averages. The method can be used to calculate time dependent as well as
stationary spectra.Comment: 8 pages, revtex, 18 figures, to be published in J.Mod.Op
Non-classical photon pair generation in atomic vapours
A scheme for the generation of non-classical pairs of photons in atomic
vapours is proposed. The scheme exploits the fact that the cross correlation of
the emission of photons from the extreme transitions of a four-level cascade
system shows anti-bunching which has not been reported earlier and which is
unlike the case of the three level cascade emission which shows bunching. The
Cauchy-Schwarz inequality which is the ratio of cross-correlation to the auto
correlation function in this case is estimated to be for
controllable time delay, and is one to four orders of magnitude larger compared
to previous experiments. The choice of Doppler free geometry in addition to the
fact that at three photon resonance the excitation/deexcitation processes occur
in a very narrow frequency band, ensures cleaner signals.Comment: 18 pages, 7 figure
Time evolution and squeezing of the field amplitude in cavity QED
We present the conditional time evolution of the electromagnetic field
produced by a cavity QED system in the strongly coupled regime. We obtain the
conditional evolution through a wave-particle correlation function that
measures the time evolution of the field after the detection of a photon. A
connection exists between this correlation function and the spectrum of
squeezing which permits the study of squeezed states in the time domain. We
calculate the spectrum of squeezing from the master equation for the reduced
density matrix using both the quantum regression theorem and quantum
trajectories. Our calculations not only show that spontaneous emission degrades
the squeezing signal, but they also point to the dynamical processes that cause
this degradation.Comment: 12 pages. Submitted to JOSA
Nonclassical effects in a driven atoms/cavity system in the presence of arbitrary driving field and dephasing
We investigate the photon statistics of light transmitted from a driven
optical cavity containing one or two atoms interacting with a single mode of
the cavity field. We treat arbitrary driving fields with emphasis on departure
from previous weak field results. In addition effects of dephasing due to
atomic transit through the cavity mode are included using two different models.
We find that both models show the nonclassical correlations are quite sensitive
to dephasing. The effect of multiple atoms on the system dynamics is
investigated by placing two atoms in the cavity mode at different positions,
therefore having different coupling strengths.Comment: 8 pages, 10 figures, minor typographical errors corrected, submitted
to Phys Rev
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