1,627 research outputs found
Tunable Entanglement, Antibunching and Saturation effects in Dipole Blockade
We report a model that makes it possible to analyze quantitatively the dipole
blockade effect on the dynamical evolution of a two two-level atom system
driven by an external laser field. The multiple excitations of the atomic
sample are taken into account. We find very large concurrence in the dipole
blockade regime. We further find that entanglement can be tuned by changing the
intensity of the exciting laser. We also report a way to lift the dipole
blockade paving the way to manipulate in a controllable way the blockade
effects. We finally report how a continuous monitoring of the dipole blockade
would be possible using photon-photon correlations of the scattered light in a
regime where the spontaneous emission would dominate dissipation in the sample.Comment: 5 pages, 5 figure
Generation of Symmetric Dicke States of Remote Qubits with Linear Optics
We propose a method for generating all symmetric Dicke states, either in the
long-lived internal levels of N massive particles or in the polarization
degrees of freedom of photonic qubits, using linear optical tools only. By
means of a suitable multiphoton detection technique, erasing Welcher-Weg
information, our proposed scheme allows the generation and measurement of an
important class of entangled multiqubit states.Comment: New version, a few modifications and a new figure, accepted in
Physical Review Letter
Traffic modeling and state feedback control for metro lines
Abstract-This paper deals with traffic modeling and control design for high-frequency metro lines. A complete discrete-event traffic model pointing out the natural instability of metro lines is presented. The traffic stability properties are analyzed and easyto-implement state feedback traffic control algorithms are designed, which guarantee the system stability. Simulations illustrate the methodology. I
Operational determination of multi-qubit entanglement classes via tuning of local operations
We present a physical setup with which it is possible to produce arbitrary
symmetric long-lived multiqubit entangled states in the internal ground levels
of photon emitters, including the paradigmatic GHZ and W states. In the case of
three emitters, where each tripartite entangled state belongs to one of two
well-defined entanglement classes, we prove a one-to-one correspondence between
well-defined sets of experimental parameters, i.e., locally tunable polarizer
orientations, and multiqubit entanglement classes inside the symmetric
subspace.Comment: Improved version. Accepted in Physical Review Letter
Quantum Imaging with Incoherent Photons
We propose a technique to obtain sub-wavelength resolution in quantum imaging
with potentially 100% contrast using incoherent light. Our method requires
neither path-entangled number states nor multi-photon absorption. The scheme
makes use of N photons spontaneously emitted by N atoms and registered by N
detectors. It is shown that for coincident detection at particular detector
positions a resolution of \lambda / N can be achieved.Comment: 4 pages, 3 figures, improved presentation. Accepted in Physical
Review Letter
Indicators of Sustainability for Production and Biodiversity Conservation in Australian Rangelands
Measure of phonon-number moments and motional quadratures through infinitesimal-time probing of trapped ions
A method for gaining information about the phonon-number moments and the
generalized nonlinear and linear quadratures in the motion of trapped ions (in
particular, position and momentum) is proposed, valid inside and outside the
Lamb-Dicke regime. It is based on the measurement of first time derivatives of
electronic populations, evaluated at the motion-probe interaction time t=0. In
contrast to other state-reconstruction proposals, based on measuring Rabi
oscillations or dispersive interactions, the present scheme can be performed
resonantly at infinitesimal short motion-probe interaction times, remaining
thus insensitive to decoherence processes.Comment: 10 pages. Accepted in JPhys
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