54 research outputs found
Jupiter Environment Tool
The Jupiter Environment Tool (JET) is a custom UI plug-in for STK that provides an interface to Jupiter environment models for visualization and analysis. Users can visualize the different magnetic field models of Jupiter through various rendering methods, which are fully integrated within STK s 3D Window. This allows users to take snapshots and make animations of their scenarios with magnetic field visualizations. Analytical data can be accessed in the form of custom vectors. Given these custom vectors, users have access to magnetic field data in custom reports, graphs, access constraints, coverage analysis, and anywhere else vectors are used within STK
Glory Oscillations in the Index of Refraction for Matter-Waves
We have measured the index of refraction for sodium de Broglie waves in gases
of Ar, Kr, Xe, and nitrogen over a wide range of sodium velocities. We observe
glory oscillations -- a velocity-dependent oscillation in the forward
scattering amplitude. An atom interferometer was used to observe glory
oscillations in the phase shift caused by the collision, which are larger than
glory oscillations observed in the cross section. The glory oscillations depend
sensitively on the shape of the interatomic potential, allowing us to
discriminate among various predictions for these potentials, none of which
completely agrees with our measurements
Single spontaneous photon as a coherent beamsplitter for an atomic matterwave
In spontaneous emission an atom in an excited state undergoes a transition to
the ground state and emits a single photon. Associated with the emission is a
change of the atomic momentum due to photon recoil. Photon emission can be
modified close to surfaces and in cavities. For an ion, localized in front of a
mirror, coherence of the emitted resonance fluorescence has been reported. In
free space experiments demonstrated that spontaneous emission destroys motional
coherence. Here we report on motional coherence created by a single spontaneous
emission event close to a mirror surface. The coherence in the free atomic
motion is verified by atom interferometry. The photon can be regarded as a
beamsplitter for an atomic matterwave and consequently our experiment extends
the original recoiling slit Gedanken experiment by Einstein to the case where
the slit is in a robust coherent superposition of the two recoils associated
with the two paths of the quanta.Comment: main text: 5 pages, 4 figure; supplementary information: 8 pages, 1
figur
Decoherence of matter waves by thermal emission of radiation
Emergent quantum technologies have led to increasing interest in decoherence
- the processes that limit the appearance of quantum effects and turn them into
classical phenomena. One important cause of decoherence is the interaction of a
quantum system with its environment, which 'entangles' the two and distributes
the quantum coherence over so many degrees of freedom as to render it
unobservable. Decoherence theory has been complemented by experiments using
matter waves coupled to external photons or molecules, and by investigations
using coherent photon states, trapped ions and electron interferometers. Large
molecules are particularly suitable for the investigation of the
quantum-classical transition because they can store much energy in numerous
internal degrees of freedom; the internal energy can be converted into thermal
radiation and thus induce decoherence. Here we report matter wave
interferometer experiments in which C70 molecules lose their quantum behaviour
by thermal emission of radiation. We find good quantitative agreement between
our experimental observations and microscopic decoherence theory. Decoherence
by emission of thermal radiation is a general mechanism that should be relevant
to all macroscopic bodies.Comment: 5 pages, 4 figure
Planck's scale dissipative effects in atom interferometry
Atom interferometers can be used to study phenomena leading to
irreversibility and dissipation, induced by the dynamics of fundamental objects
(strings and branes) at a large mass scale. Using an effective, but physically
consistent description in terms of a master equation of Lindblad form, the
modifications of the interferometric pattern induced by the new phenomena are
analyzed in detail. We find that present experimental devices can in principle
provide stringent bounds on the new effects.Comment: 12 pages, plain-Te
A Very Active Sprite-Producing Storm Observed Over Argentina
During the night of 22–23 February 2006, more than 400 middle- atmospheric optical discharges were observed above one large thunderstorm system over northeastern Argentina. These transient luminous events (TLEs) were imaged during the Southern Brazil Sprite Campaign, the first campaign to focus on TLEs over southern Brazil, northeastern Argentina, and Uruguay. All of the TLEs were imaged from the Brazilian Southern Space Observatory (SSO) near Santa Maria, which is nearly in the center of the southernmost Brazilian state of Rio Grande do Sul. Although the fields of view of the imaging cameras were too narrow to view the entire storm, the more than 400 confirmed TLEs imaged indicate that this storm ranks as the third most active TLE producer ever reported. Hence, storms in this region of South America might be some of the leading TLE generators on Earth
Phase-space formulation of quantum mechanics and quantum state reconstruction for physical systems with Lie-group symmetries
We present a detailed discussion of a general theory of phase-space
distributions, introduced recently by the authors [J. Phys. A {\bf 31}, L9
(1998)]. This theory provides a unified phase-space formulation of quantum
mechanics for physical systems possessing Lie-group symmetries. The concept of
generalized coherent states and the method of harmonic analysis are used to
construct explicitly a family of phase-space functions which are postulated to
satisfy the Stratonovich-Weyl correspondence with a generalized traciality
condition. The symbol calculus for the phase-space functions is given by means
of the generalized twisted product. The phase-space formalism is used to study
the problem of the reconstruction of quantum states. In particular, we consider
the reconstruction method based on measurements of displaced projectors, which
comprises a number of recently proposed quantum-optical schemes and is also
related to the standard methods of signal processing. A general group-theoretic
description of this method is developed using the technique of harmonic
expansions on the phase space.Comment: REVTeX, 18 pages, no figure
Decoherence, einselection, and the quantum origins of the classical
Decoherence is caused by the interaction with the environment. Environment
monitors certain observables of the system, destroying interference between the
pointer states corresponding to their eigenvalues. This leads to
environment-induced superselection or einselection, a quantum process
associated with selective loss of information. Einselected pointer states are
stable. They can retain correlations with the rest of the Universe in spite of
the environment. Einselection enforces classicality by imposing an effective
ban on the vast majority of the Hilbert space, eliminating especially the
flagrantly non-local "Schr\"odinger cat" states. Classical structure of phase
space emerges from the quantum Hilbert space in the appropriate macroscopic
limit: Combination of einselection with dynamics leads to the idealizations of
a point and of a classical trajectory. In measurements, einselection replaces
quantum entanglement between the apparatus and the measured system with the
classical correlation.Comment: Final version of the review, with brutally compressed figures. Apart
from the changes introduced in the editorial process the text is identical
with that in the Rev. Mod. Phys. July issue. Also available from
http://www.vjquantuminfo.or
Basic Atomic Physics
Contains reports on five research projects.National Science Foundation Grant PHY 96-024740National Science Foundation Grant PHY 92-21489U.S. Navy - Office of Naval Research Contract N00014-96-1-0484Joint Services Electronics Program Grant DAAHO4-95-1-0038National Science Foundation Grant PHY95-14795U.S. Army Research Office Contract DAAHO4-94-G-0170U.S. Army Research Office Contract DAAG55-97-1-0236U.S. Army Research Office Contract DAAH04-95-1-0533U.S. Navy - Office of Naval Research Contract N00014-96-1-0432National Science Foundation Contract PHY92-22768David and Lucile Packard Foundation Grant 96-5158National Science Foundation Grant PHY 95-01984U.S. Army Research OfficeU.S. Navy - Office of Naval Research Contract N00014-96-1-0485AASERT N00014-94-1-080
Basic Atomic Physics
Contains reports on five research projects.Joint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Grant PHY 92-21489U.S. Navy - Office of Naval Research Grant N00014-90-J-1322National Science Foundation Grant PHY95-14795Charles S. Draper Laboratory Contract DL-H-484775U.S. Army Research Office Contract DAAH04-94-G-0170U.S. Army Research Office Contract DAAH04-95-1-0533U.S. Navy - Office of Naval Research Contract N00014-89-J-1207U.S. Navy - Office of Naval Research Contract N000014-96-1-0432David and Lucile Packard Foundation Grant 96-5158National Science Foundation Grant PHY95-01984U.S. Army - Office of ResearchU.S. Navy - Office of Naval Research Contract N00014-96-1-0485U.S. Navy - Office of Naval Research AASERT N00014-94-1-080
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