6,838 research outputs found
Spectral properties of the largest asteroids associated with Taurid Complex
We obtained spectra of six of the largest asteroids (2201, 4183, 4486, 5143,
6063, and 269690) associated with Taurid complex. The observations were made
with the IRTF telescope equipped with the spectro-imager SpeX. Their taxonomic
classification is made using Bus-DeMeo taxonomy. The asteroid spectra are
compared with the meteorite spectra from the Relab database. Mineralogical
models were applied to determine their surface composition. All the spectral
analysis is made in the context of the already published physical data.
  Five of the objects studied in this paper present spectral characteristics
similar to the S taxonomic complex. The spectra of ordinary chondrites
(spanning H, L, and LL subtypes) are the best matches for these asteroid
spectra. {\bf The asteroid} (269690) 1996 RG3 presents a flat featureless
spectrum which could be associated to a primitive C-type object. The increased
reflectance above 2.1 microns constrains its geometrical albedo to a value
around 0.03.
  While there is an important dynamical grouping among the Taurid Complex
asteroids, the spectral data of the largest objects do not support a common
cometary origin. Furthermore, there are significant variations between the
spectra acquired until now.Comment: Accepted for publication in A&
Recovery of entanglement lost in entanglement manipulation
When an entangled state is transformed into another one with probability one
by local operations and classical communication, the quantity of entanglement
decreases. This letter shows that entanglement lost in the manipulation can be
partially recovered by an auxiliary entangled pair. As an application, a
maximally entangled pair can be obtained from two partially entangled pairs
with probability one. Finally, this recovery scheme reveals a fundamental
property of entanglement relevant to the existence of incomparable states.Comment: 4 pages, 2 figures, REVTeX; minor correction
Weak Equivalence Principle Test on a Sounding Rocket
SR-POEM, our principle of equivalence measurement on a sounding rocket, will
compare the free fall rate of two substances yielding an uncertainty of E-16 in
the estimate of \eta. During the past two years, the design concept has matured
and we have been working on the required technology, including a laser gauge
that is self aligning and able to reach 0.1 pm per root hertz for periods up to
40 s. We describe the status and plans for this project.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
  Bloomington, Indiana, June 28-July 2, 201
Near-infrared colors of minor planets recovered from VISTA - VHS survey (MOVIS)
The Sloan Digital Sky Survey (SDSS) and Wide-field Infrared Survey Explorer
(WISE) provide information about the surface composition of about 100,000 minor
planets. The resulting visible colors and albedos enabled us to group them in
several major classes, which are a simplified view of the diversity shown by
the few existing spectra. We performed a serendipitous search in VISTA-VHS
observations using a pipeline developed to retrieve and process the data that
corresponds to solar system objects (SSo). The colors and the magnitudes of the
minor planets observed by the VISTA survey are compiled into three catalogs
that are available online: the detections catalog (MOVIS-D), the magnitudes
catalog (MOVIS-M), and the colors catalog (MOVIS-C). They were built using the
third data release of the survey (VISTA VHS-DR3). A total of 39,947 objects
were detected, including 52 NEAs, 325 Mars Crossers, 515 Hungaria asteroids,
38,428 main-belt asteroids, 146 Cybele asteroids, 147 Hilda asteroids, 270
Trojans, 13 comets, 12 Kuiper Belt objects and Neptune with its four
satellites. The colors found for asteroids with known spectral properties
reveal well-defined patterns corresponding to different mineralogies. The
distributions of MOVIS-C data in color-color plots shows clusters identified
with different taxonomic types. All the diagrams that use (Y-J) color separate
the spectral classes more effectively than the (J-H) and (H-Ks) plots used
until now: even for large color errors (<0.1), the plots (Y-J) vs (Y-Ks) and
(Y-J) vs (J-Ks) provide the separation between S-complex and C-complex. The end
members A, D, R, and V-types occupy well-defined regions.Comment: 19 pages, 16 figure
Fast light, slow light, and phase singularities: a connection to generalized weak values
We demonstrate that Aharonov-Albert-Vaidman (AAV) weak values have a direct
relationship with the response function of a system, and have a much wider
range of applicability in both the classical and quantum domains than
previously thought. Using this idea, we have built an optical system, based on
a birefringent photonic crystal, with an infinite number of weak values. In
this system, the propagation speed of a polarized light pulse displays both
superluminal and slow light behavior with a sharp transition between the two
regimes. We show that this system's response possesses two-dimensional,
vortex-antivortex phase singularities. Important consequences for optical
signal processing are discussed.Comment: 9 pages, 4 figures, accepted in Physical Review Letters (2003
Sufficient conditions for three-particle entanglement and their tests in recent experiments
We point out a loophole problem in some recent experimental claims to produce
three-particle entanglement. The problem consists in the question whether
mixtures of two-particle entangled states might suffice to explain the
experimental data.
  In an attempt to close this loophole, we review two sufficient conditions
that distinguish between N-particle states in which all N particles are
entangled to each other and states in which only M particles are entangled
(with M<N). It is shown that three recent experiments to obtain three-particle
entangled states (Bouwmeester et al., Pan et al., and Rauschenbeutel et al.) do
not meet these conditions. We conclude that the question whether these
experiments provide confirmation of three-particle entanglement remains
unresolved. We also propose modifications of the experiments that would make
such confirmation feasible.Comment: 16 page
New HErschel Multi-wavelength Extragalactic Survey of Edge-on Spirals (NHEMESES)
Edge-on spiral galaxies offer a unique perspective on the vertical structure
of spiral disks, both stars and the iconic dark dustlanes. The thickness of
these dustlanes can now be resolved for the first time with Herschel in
far-infrared and sub-mm emission. We present NHEMESES, an ongoing project that
targets 12 edge-on spiral galaxies with the PACS and SPIRE instruments on
Herschel. These vertically resolved observations of edge-on spirals will impact
on several current topics.
  First and foremost, these Herschel observations will settle whether or not
there is a phase change in the vertical structure of the ISM with disk mass.
Previously, a dramatic change in dustlane morphology was observed as in massive
disks the dust collapses into a thin lane. If this is the case, the vertical
balance between turbulence and gravity dictates the ISM structure and
consequently star-formation and related phenomena (spiral arms, bars etc.). We
specifically target lower mass nearby edge-ons to complement existing Herschel
observations of high-mass edge-on spirals (the HEROES project).
  Secondly, the combined data-set, together with existing Spitzer observations,
will drive a new generation of spiral disk Spectral Energy Distribution models.
These model how dust reprocesses starlight to thermal emission but the dust
geometry remains the critical unknown.
  And thirdly, the observations will provide an accurate and unbiased census of
the cold dusty structures occasionally seen extending out of the plane of the
disk, when backlit by the stellar disk. To illustrate the NHEMESES project, we
present early results on NGC 4244 and NGC 891, two well studies examples of a
low and high-mass edge-on spiral.Comment: 3 pages, 4 figures, to appear in the proceedings of IAU 284, "The
  Spectral Energy Distribution of Galaxies", (SED2011), 5-9 September 2011,
  Preston, UK, editors, R.J. Tuffs & C.C.Popescu (v2 updated metadata
On the volume of the set of mixed entangled states
A natural measure in the space of density matrices describing N-dimensional
quantum systems is proposed. We study the probability P that a quantum state
chosen randomly with respect to the natural measure is not entangled (is
separable). We find analytical lower and upper bounds for this quantity.
Numerical calculations give P = 0.632 for N=4 and P=0.384 for N=6, and indicate
that P decreases exponentially with N. Analysis of a conditional measure of
separability under the condition of fixed purity shows a clear dualism between
purity and separability: entanglement is typical for pure states, while
separability is connected with quantum mixtures. In particular, states of
sufficiently low purity are necessarily separable.Comment: 10 pages in LaTex - RevTex + 4 figures in eps. submitted to Phys.
  Rev. 
Mining the ESO WFI and INT WFC archives for known Near Earth Asteroids. Mega-Precovery software
The ESO/MPG WFI and the INT WFC wide field archives comprising 330,000 images
were mined to search for serendipitous encounters of known Near Earth Asteroids
(NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 asteroids (44
PHAs and 108 other NEAs) were identified using the PRECOVERY software, their
astrometry being measured on 761 images and sent to the Minor Planet Centre.
Both recoveries and precoveries were reported, including prolonged orbital arcs
for 18 precovered objects and 10 recoveries. We analyze all new opposition data
by comparing the orbits fitted before and after including our contributions. We
conclude the paper presenting Mega-Precovery, a new online service focused on
data mining of many instrument archives simultaneously for one or a few given
asteroids. A total of 28 instrument archives have been made available for
mining using this tool, adding together about 2.5 million images forming the
Mega-Archive.Comment: Accepted for publication in Astronomische Nachrichten (Sep 2012
Mixed-state entanglement and distillation: is there a ``bound'' entanglement in nature?
It is shown that if a mixed state can be distilled to the singlet form, it
must violate partial transposition criterion [A. Peres, Phys. Rev. Lett. 76,
1413 (1996)]. It implies that there are two qualitatively different types of
entanglement: ``free'' entanglement which is distillable, and ``bound''
entanglement which cannot be brought to the singlet form useful for quantum
communication purposes. Possible physical meaning of the result is discussed.Comment: RevTeX, 4 page
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