963 research outputs found
Proposal for teleportation of the wave function of a massive particle
We propose a scheme for teleporting an atomic center-of-mass wave function
between distant locations. The scheme uses interactions in cavity quantum
electrodynamics to facilitate a coupling between the motion of an atom trapped
inside a cavity and external propagating light fields. This enables the
distribution of quantum entanglement and the realization of the required
motional Bell-state analysis.Comment: 4 pages, 3 figure
Supervisors\u27 Perceptions of Specified Competencies in Selected Southeastern States
The problem of this study was to determine if differences existed in the supervisors\u27 perceptions of the importance of specified supervisory competencies. A list of thirty-six competencies which had been developed and validated by Ben M. Harris was adopted. Competencies were defined as any combination of knowledge and skill that is adequate for accomplishing some specified outcome. Included in the study were supervisors at the state department level in nine Southeastern states which were as follows: Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, South Carolina, Tennessee, and Virginia. Forty supervisors at the state department level were randomly selected from each state. Thirty-six null hypotheses were formulated to be tested at the .05 level of significance. Each hypothesis concerned a specific competency. Competencies were grouped according to task area. The analysis of variance was used as the first step in data analysis. This yielded an F ratio which indicated whether or not a significant difference existed. If a significant difference was revealed a follow-up test was conducted to determine where specific differences lay. The Newman-Keuls procedure was used for this purpose. Significant differences were revealed in only eight of the thirty-six hypotheses tested which were concerned with the following competencies: (A-3) Developing and adapting curricula; (C-2) Recruiting and selecting personnel; (C-3) Assigning personnel; (F-3) Designing in-service training sessions; (F-4) Conducting in-service training sessions; (G-1) Informing the public; (H-1) Developing educational specifications; (I-4) Analyzing and interpreting data. Thus, the null hypothesis was rejected for hypotheses 3, 8, 9, 19, 20, 27, 30, and 36. Major conclusions indicated that generally supervisors from the nine states did not differ significantly. This was not consistent with the diversity of roles and perceptions of supervisors as proclaimed by the literature. Even when significant differences existed specific differences between states were minimal. The F probability in seventeen competencies exceeded the 0.2500 level which indicated little difference and possibly some correlation existed. Recommendations included future research in supervision, clarification of supervisory roles and job descriptions, and implications for universities with graduate programs in supervision
Proposed realization of the Dicke-model quantum phase transition in an optical cavity QED system
The Dicke model describing an ensemble of two-state atoms interacting with a single quantized mode of the electromagnetic field (with omission of the Â^2 term) exhibits a zero-temperature phase transition at a critical value of the dipole coupling strength. We propose a scheme based on multilevel atoms and cavity-mediated Raman transitions to realize an effective Dicke model operating in the phase transition regime. Optical light from the cavity carries signatures of the critical behavior, which is analyzed for the thermodynamic limit where the number of atoms is very large
Deviations from early--time quasilinear behaviour for the quantum kicked rotor near the classical limit
We present experimental measurements of the mean energy for the atom optics
kicked rotor after just two kicks. The energy is found to deviate from the
quasi--linear value for small kicking periods. The observed deviation is
explained by recent theoretical results which include the effect of a
non--uniform initial momentum distribution, previously applied only to systems
using much colder atoms than ours
Mimicking a Squeezed Bath Interaction: Quantum Reservoir Engineering with Atoms
The interaction of an atomic two-level system and a squeezed vacuum leads to
interesting novel effects in atomic dynamics, including line narrowing in
resonance fluorescence and absorption spectra, and a suppressed (enhanced)
decay of the in-phase and out-of phase component of the atomic polarization. On
the experimental side these predictions have so far eluded observation,
essentially due to the difficulty of embedding atoms in a 4 pi squeezed vacuum.
In this paper we show how to ``engineer'' a squeezed-bath-type interaction for
an effective two-level system. In the simplest example, our two-level atom is
represented by the two ground levels of an atom with angular momentum J=1/2 ->
J=1/2 transition (a four level system) which is driven by (weak) laser fields
and coupled to the vacuum reservoir of radiation modes. Interference between
the spontaneous emission channels in optical pumping leads to a squeezed bath
type coupling, and thus to symmetry breaking of decay on the Bloch sphere. With
this system it should be possible to observe the effects predicted in the
context of squeezed bath - atom interactions. The laser parameters allow one to
choose properties of the squeezed bath interaction, such as the (effective)
photon number expectation number N and the squeezing phase phi. We present
results of a detailed analytical and numerical study.Comment: 24 pages, 8 figure
Coupling of effective one-dimensional two-level atoms to squeezed light
A cavity QED system is analyzed which duplicates the dynamics of a two-level
atom in free space interacting exclusively with broadband squeezed light. We
consider atoms in a three or four-level Lambda-configuration coupled to a
high-finesse optical cavity which is driven by a squeezed light field. Raman
transitions are induced between a pair of stable atomic ground states via the
squeezed cavity mode and coherent driving fields. An analysis of the reduced
master equation for the atomic ground states shows that a three-level atomic
system has insufficient parameter flexibility to act as an effective two-level
atom interacting exclusively with a squeezed reservoir. However, the inclusion
of a fourth atomic level, coupled dispersively to one of the two ground states
by an auxiliary laser field, introduces an extra degree of freedom and enables
the desired interaction to be realised. As a means of detecting the reduced
quadrature decay rate of the effective two-level system, we examine the
transmission spectrum of a weak coherent probe field incident upon the cavity
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