250 research outputs found
Phenomenon of the time-reversal-violating photon polarization plane rotation by a gas placed to an electric field
T-odd P-odd phenomenon of the photon polarization plane rotation (circular
dichroism) is considered for an atomic (molecules) gas placed to an electric
field. The expression for the T non-invariant polarizability of an atom
(molecule) placed to an electric field is obtained. It is shown that the T-odd
plane rotation angle increases when the interaction energy of an atom
(molecule) with an electric field is the same order as the opposite parity
levels spacing.Comment: 9 pages, Late
Simplified quantum logic with trapped ions
We describe a simplified scheme for quantum logic with a collection of
laser-cooled trapped atomic ions. Building on the scheme of Cirac and Zoller,
we show how the fundamental controlled-NOT gate between a collective mode of
ion motion and the internal states of a single ion can be reduced to a single
laser pulse, and the need for a third auxiliary internal electronic state can
be eliminated.Comment: 8 pages, PostScript, submitted to Physical Review A, Rapid
Communication
Decoherence in ion traps due to laser intensity and phase fluctuations
We consider one source of decoherence for a single trapped ion due to
intensity and phase fluctuations in the exciting laser pulses. For simplicity
we assume that the stochastic processes involved are white noise processes,
which enables us to give a simple master equation description of this source of
decoherence. This master equation is averaged over the noise, and is sufficient
to describe the results of experiments that probe the oscillations in the
electronic populations as energy is exchanged between the internal and
electronic motion. Our results are in good qualitative agreement with recent
experiments and predict that the decoherence rate will depend on vibrational
quantum number in different ways depending on which vibrational excitation
sideband is used.Comment: 2 figures, submitted to PR
Realization of a space reversal operator
In this paper we propose the realization of a bosonic-fermionic interaction
in the context of trapped ions whose effect upon the ion center of mass degrees
of freedom is properly speaking a spatial inversion. The physical system and
its features are accurately described and some applications are briefly
discussed.Comment: 9 pages; to appear in Rep. Math. Phys., in summer 200
Quantum harmonic oscillator state synthesis and analysis
Experiments are described in which a single, harmonically bound, beryllium
ion in a Paul trap is put into Fock, thermal, coherent, squeezed, and
Schroedinger cat states. Experimental determinations of the density matrix and
the Wigner function are described. A simple calculation of the decoherence of a
superposition of coherent states due to an external electric field is given.Comment: 13 pages, LaTeX2e, special style file spie.sty included, 11 eps
figures included using epsfig, graphicx, subfigure, floatflt macros. To
appear in Proc. Conf. on Atom Optics, San Jose, CA, Feb. 1997, edited by M.
G. Prentiss and W. D. Phillips, SPIE Proc. # 299
Counterfactual Statements and Weak Measurements: an Experimental Proposal
A recent analysis [quant-ph/0104062] suggests that weak measurements can be
used to give observational meaning to counterfactual reasoning in quantum
physics. A weak measurement is predicted to assign a negative unit population
to a specific state in an interferometric Gedankenexperiment proposed by Hardy.
We propose an experimental implementation with trapped ions of the
Gedankenexperiment and of the weak measurement. In our standard quantum
mechanical analysis of the proposal no states have negative population, but we
identify the registration of a negative population by particles being displaced
on average in the direction opposite to a force acting upon them
On Collective Effects in Cavity Quantum Electrodynamics
We investigate the role of collective effects in the micromaser system as
used in various studies of the physics of cavity electrodynamics. We focus our
attention on the effect on large-time correlations due to multi-atom
interactions. The influence of detection efficiencies and collective effects on
the appearance of trapping states at low temperatures is also found to be of
particular importance.Comment: 10 pages, 7 figures, 36 reference
Two-photon interaction between trapped ions and cavity fields
In this paper, we generalize the ordinary two-photon Jaynes-Cummings model
(TPJCM) by considering the atom (or ion) to be trapped in a simple harmonic
well. A typical setup would be an optical cavity containing a single ion in a
Paul trap. Due to the inclusion of atomic vibrational motion, the atom-field
coupling becomes highly nonlinear what brings out quite different behaviors for
the system dynamics when compared to the ordinary TPJCM. In particular, we
derive an effective two-photon Hamiltonian with dependence on the number
operator of the ion's center-of-mass motion. This dependence occurs both in the
cavity induced Stark-shifs and in the ion-field coupling, and its role in the
dynamics is illustrated by showing the time evolution of the probability of
occupation of the electronic levels for simple initial preparations of the
state of the system.Comment: 9 pages, 10 figure
Quantum signatures of chaos in the dynamics of a trapped ion
We show how a nonlinear chaotic system, the parametrically kicked nonlinear
oscillator, may be realised in the dynamics of a trapped, laser-cooled ion,
interacting with a sequence of standing wave pulses. Unlike the original
optical scheme [G.J.Milburn and C.A.Holmes, Phys. Rev A, 44, p4704, (1991)],
the trapped ion enables strongly quantum dynamics with minimal dissipation.
This should permit an experimental test of one of the quantum signatures of
chaos; irregular collapse and revival dynamics of the average vibrational
energy.Comment: 9 pages, 9 Postscript figures, Revtex, submitted to Phys. Rev.
Stof in Pluimveestallen
Het PP doet onderzoek naar het verminderen van stofconcentraties in de stallucht. Het doel van het hier beschreven vooronderzoek was het verkrijgen van meer inzicht in stofconcentraties in de stallucht bij kalkoenen- en vleeskuikenstallen en het opstellen van een meetprotocol voor stofmetingen in pluimveestallen
- …