756 research outputs found
Compact Source of EPR Entanglement and Squeezing at Very Low Noise Frequencies
We report on the experimental demonstration of strong quadrature EPR
entanglement and squeezing at very low noise sideband frequencies produced by a
single type-II, self-phase-locked, frequency degenerate optical parametric
oscillator below threshold. The generated two-mode squeezed vacuum state is
preserved for noise frequencies as low as 50 kHz. Designing simple setups able
to generate non-classical states of light in the kHz regime is a key challenge
for high sensitivity detection of ultra-weak physical effects such as
gravitational wave or small beam displacement
Report of the ultraviolet and visible sensors panel
In order to meet the science objectives of the Astrotech 21 mission set the Ultraviolet (UV) and Visible Sensors Panel made a number of recommendations. In the UV wavelength range of 0.01 to 0.3 micro-m the focus is on the need for large format high quantum efficiency, radiation hard 'solar-blind' detectors. Options recommended for support include Si and non-Si charge coupled devices (CCDs) as well as photocathodes with improved microchannel plate readouts. For the 0.3 to 0.9 micro-m range, it was felt that Si CCDs offer the best option for high quantum efficiencies at these wavelengths. In the 0.9 to 2.5 micro-m the panel recommended support for the investigation of monolithic arrays. Finally, the panel noted that the implementation of very large arrays will require new data transmission, data recording, and data handling technologies
Cooling to the Ground State of Axial Motion for One Atom Strongly Coupled to an Optical Cavity
Localization to the ground state of axial motion is demonstrated for a
single, trapped atom strongly coupled to the field of a high finesse optical
resonator. The axial atomic motion is cooled by way of coherent Raman
transitions on the red vibrational sideband. An efficient state detection
scheme enabled by strong coupling in cavity QED is used to record the Raman
spectrum, from which the state of atomic motion is inferred. We find that the
lowest vibrational level of the axial potential with zero-point energy 13uK is
occupied with probability P0~0.95.Comment: 5 pages, 4 figure
Non-symmetric entanglement of atomic ensembles
The entanglement of multi-atom quantum states is considered. In order to
cancel noise due to inhomogeneous light atom coupling, the concept of matched
multi-atom observables is proposed. As a means to eliminate an important form
of decoherence this idea should be of broad relevance for quantum information
processing with atomic ensembles. The general approach is illustrated on the
example of rotation angle measurement, and it is shown that the multi-atom
states that were thought to be only weakly entangled can exhibit near-maximum
entanglement.Comment: to appear in Physical Review Letter
Non-Markovian Dynamics of Entanglement for Multipartite Systems
Entanglement dynamics for a couple of two-level atoms interacting with
independent structured reservoirs is studied using a non-perturbative approach.
It is shown that the revival of atom entanglement is not necessarily
accompanied by the sudden death of reservoir entanglement, and vice versa. In
fact, atom entanglement can revive before, simultaneously or even after the
disentanglement of reservoirs. Using a novel method based on the population
analysis for the excited atomic state, we present the quantitative criteria for
the revival and death phenomena. For giving a more physically intuitive
insight, the quasimode Hamiltonian method is applied. Our quantitative analysis
is helpful for the practical engineering of entanglement.Comment: 10 pages and 4 figure
Simulations of atomic trajectories near a dielectric surface
We present a semiclassical model of an atom moving in the evanescent field of
a microtoroidal resonator. Atoms falling through whispering-gallery modes can
achieve strong, coherent coupling with the cavity at distances of approximately
100 nanometers from the surface; in this regime, surface-induced Casmir-Polder
level shifts become significant for atomic motion and detection. Atomic transit
events detected in recent experiments are analyzed with our simulation, which
is extended to consider atom trapping in the evanescent field of a microtoroid.Comment: 29 pages, 10 figure
Quantum jumps in hydrogen-like systems
In this paper it is shown that the Lyman- transition of a single
hydrogen-like system driven by a laser exhibits macroscopic dark periods,
provided there exists an additional constant electric field. We describe the
photon-counting process under the condition that the polarization of the laser
coincides with the direction of the constant electric field. The theoretical
results are given for the example of . We show that the emission
behavior depends sensitively on the Lamb shift (W.E. Lamb, R.C. Retherford,
Phys. Rev. 72, 241 (1947)) between the and energy levels.
A possibly realizable measurement of the mean duration of the dark periods
should give quantitative information about the above energy difference by using
the proposed photon-counting process.Comment: 7 pages RevTeX + 2 figures Phys. Rev A accepte
Conditional large Fock state preparation and field state reconstruction in Cavity QED
We propose a scheme for producing large Fock states in Cavity QED via the
implementation of a highly selective atom-field interaction. It is based on
Raman excitation of a three-level atom by a classical field and a quantized
field mode. Selectivity appears when one tunes to resonance a specific
transition inside a chosen atom-field subspace, while other transitions remain
dispersive, as a consequence of the field dependent electronic energy shifts.
We show that this scheme can be also employed for reconstructing, in a new and
efficient way, the Wigner function of the cavity field state.Comment: 4 Revtex pages with 3 postscript figures. Submitted for publicatio
Nonclassical Interference Effects In The Radiation From Coherently Driven Uncorrelated Atoms
We demonstrate the existence of new nonclassical correlations in the
radiation of two atoms, which are coherently driven by a continuous laser
source. The photon-photon-correlations of the fluorescence light show a spatial
interferene pattern not present in a classical treatment. A feature of the new
phenomenon is, that bunched and antibunched light is emitted in different
spatial directions. The calculations are performed analytically. It is pointed
out, that the correlations are induced by state reduction due to the
measurement process when the detection of the photons does not distinguish
between the atoms. It is interesting to note, that the phenomena show up even
without any interatomic interaction.Comment: 4 pages, 6 Figure
Trapping of single atoms in cavity QED
By integrating the techniques of laser cooling and trapping with those of
cavity quantum electrodynamics (QED), single Cesium atoms have been trapped
within the mode of a small, high finesse optical cavity in a regime of strong
coupling. The observed lifetime for individual atoms trapped within the cavity
mode is ms, and is limited by fluctuations of light forces
arising from the far-detuned intracavity field. This initial realization of
trapped atoms in cavity QED should enable diverse protocols in quantum
information science.Comment: 4 pages, 4 figure
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