11,501 research outputs found
Stellar Population Challenge: analysis of M67 with the VO
In this poster we present the analysis of the CMD of M67 (proposed in the
Stellar Population Challenge) performed with VO applications. We found that,
although the VO environment is still not ready to perform a complete analysis,
its use provides highly useful additional information for the analysis. Thanks
to the current VO framework, we are able to identify stars in the provided CMD
that are not suitable for isochrone fitting. Additionally, we can complete our
knowledge of this cluster extending the analysis to IR colors, which were not
provided in the original data but that are available thanks to the VO. On the
negative side, we find it difficult to access theoretical data from VO
applications, so, currently, it is not possible to perform completely the
analysis of the cluster inside the VO framework. However it is expected that
the situation will improve in a near future.Comment: Stellar Populations as Building Blocks of Galaxies, Proceedings of
IAU Symposium #241. Edited by A. Vazdekis and R. F. Peletier. Cambridge:
Cambridge University Press, 2007, pp. 173-17
Generation and purification of maximally-entangled atomic states in optical cavities
We present a probabilistic scheme for generating and purifying
maximally-entangled states of two atoms inside an optical cavity via no-photon
detection in the output cavity mode, where ideal detectors may not be required.
The intermediate mixed states can be continuously "filtered" so as to violate
Bell inequalities in a parametrized manner. The scheme relies on an additional
strong-driving field that yields unusual dynamics in cavity QED experiments,
simultaneously realizing Jaynes-Cummings and anti-Jaynes-Cummings interactions.Comment: 4 pages and 3 figure
Tavis-Cummings model and collective multi-qubit entanglement in trapped ions
We present a method of generating collective multi-qubit entanglement via
global addressing of an ion chain following the guidelines of the
Tavis-Cummings model, where several qubits are coupled to a collective motional
mode. We show that a wide family of Dicke states and irradiant states can be
generated by single global laser pulses, unitarily or helped with suitable
postselection techniques.Comment: 6 pages, 3 figures. Accepted for publication in Physical Review
Quantum Memristors in Quantum Photonics
We propose a method to build quantum memristors in quantum photonic
platforms. We firstly design an effective beam splitter, which is tunable in
real-time, by means of a Mach-Zehnder-type array with two equal 50:50 beam
splitters and a tunable retarder, which allows us to control its reflectivity.
Then, we show that this tunable beam splitter, when equipped with weak
measurements and classical feedback, behaves as a quantum memristor. Indeed, in
order to prove its quantumness, we show how to codify quantum information in
the coherent beams. Moreover, we estimate the memory capability of the quantum
memristor. Finally, we show the feasibility of the proposed setup in integrated
quantum photonics
Instantaneous Measurement of field quadrature moments and entanglement
We present a method of measuring expectation values of quadrature moments of
a multimode field through two-level probe ``homodyning''. Our approach is based
on an integral transform formalism of measurable probe observables, where
analytically derived kernels unravel efficiently the required field information
at zero interaction time, minimizing decoherence effects. The proposed scheme
is suitable for fields that, while inaccessible to a direct measurement, enjoy
one and two-photon Jaynes-Cummings interactions with a two-level probe, like
spin, phonon, or cavity fields. Available data from previous experiments are
used to confirm our predictions.Comment: 4 pages, no figures, modified version with experimental estimation
Selective interactions in trapped ions: state reconstruction and quantum logic
We propose the implementation of selective interactions of atom-motion
subspaces in trapped ions. These interactions yield resonant exchange of
population inside a selected subspace, leaving the others in a highly
dispersive regime. Selectivity allows us to generate motional Fock (and other
nonclassical) states with high purity out of a wide class of initial states,
and becomes an unconventional cooling mechanism when the ground state is
chosen. Individual population of number states can be distinctively measured,
as well as the motional Wigner function. Furthermore, a protocol for
implementing quantum logic through a suitable control of selective subspaces is
presented.Comment: 4 revtex4 pages and 2 eps figures. Submitted for publicatio
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