1,212 research outputs found
The spectroscopic orbits and the geometrical configuration of the symbiotic binary AR Pavonis
We analyze optical and near infrared spectra of intermediate and high
resolution of the eclipsing symbiotic system AR Pavonis. We have obtained the
radial velocity curves for the red and the hot component from the M-giant
absorption lines and from the wings of Halpha, H and He II4686 emission
profiles, respectively. From the orbital elements we have derived the masses,
Mgiant=2.5 and Mhot =1.0 solar masses, for the red giant and the hot component,
respectively. We also present and discuss radial velocity patterns in the blue
cF absorption spectrum as well as various emission lines. In particular, we
confirm that the blue absorption lines are associated with the hot component.
The radial velocity curve of the blue absorption system, however, does not
track the hot companion's orbital motion in a straightforward way, and its
departures from an expected circular orbit are particularly strong when the hot
component is active. We suggest that the cF-type absorption system is formed in
material streaming from the giant presumably in a region where the stream
encounters an accretion disk or an extended envelope around the hot component.
The broad emission wings originate from the inner accretion disk or the
envelope around the hot star.We also suggest that the central absorption in H
profiles is formed in a neutral portion of the cool giant's wind which is
strongly concentrated towards the orbital plane. The nebula in AR Pav seems to
be bounded by significant amount of neutral material in the orbital plane. The
forbidden emission lines are probably formed in low density ionized regions
extended in polar directions and/or the wind-wind interaction zone.Comment: 12 pages, 5 figures, accepted by A&
New dynamical scaling universality for quantum networks across adiabatic quantum phase transitions
We reveal universal dynamical scaling behavior across adiabatic quantum phase
transitions (QPTs) in networks ranging from traditional spatial systems (Ising
model) to fully connected ones (Dicke and Lipkin-Meshkov-Glick models). Our
findings, which lie beyond traditional critical exponent analysis and adiabatic
perturbation approximations, are applicable even where excitations have not yet
stabilized and hence provide a time-resolved understanding of QPTs encompassing
a wide range of adiabatic regimes. We show explicitly that even though two
systems may traditionally belong to the same universality class, they can have
very different adiabatic evolutions. This implies more stringent conditions
need to be imposed than at present, both for quantum simulations where one
system is used to simulate the other, and for adiabatic quantum computing
schemes.Comment: 5 pages, 3 figures, plus supplementary material (6 pages, 1 figure
Large dynamic light-matter entanglement from driving neither too fast nor too slow
A significant problem facing next-generation quantum technologies is how to
generate and manipulate macroscopic entanglement in light and matter systems.
Here we report a new regime of dynamical light-matter behavior in which a
giant, system-wide entanglement is generated by varying the light-matter
coupling at \emph{intermediate} velocities. This enhancement is far larger and
broader-ranged than that occurring near the quantum phase transition of the
same model under adiabatic conditions. By appropriate choices of the coupling
within this intermediate regime, the enhanced entanglement can be made to
spread system-wide or to reside in each subsystem separately.Comment: 7 pages, 7 figure
Robust quantum correlations in out-of-equilibrium matter-light systems
High precision macroscopic quantum control in interacting light-matter
systems remains a significant goal toward novel information processing and
ultra-precise metrology. We show that the out-of-equilibrium behavior of a
paradigmatic light-matter system (Dicke model) reveals two successive stages of
enhanced quantum correlations beyond the traditional schemes of near-adiabatic
and sudden quenches. The first stage features magnification of matter-only and
light-only entanglement and squeezing due to effective non-linear
self-interactions. The second stage results from a highly entangled
light-matter state, with enhanced superradiance and signatures of chaotic and
highly quantum states. We show that these new effects scale up consistently
with matter system size, and are reliable even in dissipative environments.Comment: 14 pages, 6 figure
Quantum Hysteresis in Coupled Light-Matter Systems
We investigate the non-equilibrium quantum dynamics of a canonical
light-matter system, namely the Dicke model, when the light-matter interaction
is ramped up and down through a cycle across the quantum phase transition. Our
calculations reveal a rich set of dynamical behaviors determined by the cycle
times, ranging from the slow, near adiabatic regime through to the fast, sudden
quench regime. As the cycle time decreases, we uncover a crossover from an
oscillatory exchange of quantum information between light and matter that
approaches a reversible adiabatic process, to a dispersive regime that
generates large values of light-matter entanglement. The phenomena uncovered in
this work have implications in quantum control, quantum interferometry, as well
as in quantum information theory.Comment: 9 pages and 4 figure
Functional advantages offered by many-body coherences in biochemical systems
Quantum coherence phenomena driven by electronic-vibrational (vibronic)
interactions, are being reported in many pulse (e.g. laser) driven chemical and
biophysical systems. But what systems-level advantage(s) do such many-body
coherences offer to future technologies? We address this question for pulsed
systems of general size N, akin to the LHCII aggregates found in green plants.
We show that external pulses generate vibronic states containing particular
multipartite entanglements, and that such collective vibronic states increase
the excitonic transfer efficiency. The strength of these many-body coherences
and their robustness to decoherence, increase with aggregate size N and do not
require strong electronic-vibrational coupling. The implications for energy and
information transport are discussed.Comment: arXiv admin note: text overlap with arXiv:1706.0776
Pulsed Generation of Quantum Coherences and Non-classicality in Light-Matter Systems
We show that a pulsed stimulus can be used to generate many-body quantum
coherences in light-matter systems of general size. Specifically, we calculate
the exact real-time evolution of a driven, generic out-of-equilibrium system
comprising an arbitrary number N qubits coupled to a global boson field. A
novel form of dynamically-driven quantum coherence emerges for general N and
without having to access the empirically challenging strong-coupling regime.
Its properties depend on the speed of the changes in the stimulus.
Non-classicalities arise within each subsystem that have eluded previous
analyses. Our findings show robustness to losses and noise, and have potential
functional implications at the systems level for a variety of nanosystems,
including collections of N atoms, molecules, spins, or superconducting qubits
in cavities -- and possibly even vibration-enhanced light harvesting processes
in macromolecules.Comment: 9 pages, 4 figure
Finding evolved stars in the inner Galactic disk with Gaia
The Bulge Asymmetries and Dynamical Evolution (BAaDE) survey will provide
positions and line-of-sight velocities of ~20,000 evolved, maser bearing stars
in the Galactic plane. Although this Galactic region is affected by optical
extinction, BAaDE targets may have Gaia cross-matches, eventually providing
additional stellar information. In an initial attempt to cross-match BAaDE
targets with Gaia, we have found more than 5,000 candidates. Of these, we may
expect half to show SiO emission, which will allow us to obtain velocity
information. The cross-match is being refined to avoid false positives using
different criteria based on distance analysis, flux variability, and color
assessment in the mid- and near-IR. Once the cross-matches can be confirmed, we
will have a unique sample to characterize the stellar population of evolved
stars in the Galactic bulge, which can be considered fossils of the Milky Way
formation.Comment: To appear in the Proceedings of the IAU Symposium No. 330:
"Astrometry and Astrophysics in the Gaia sky
Management discriminant properties in semiarid soils
The physical properties of coarse - textured soils in semiarid regions often deteriorate with use. We hypostatized that the changes in the physical properties of the soil were related to the cropping sistem employed. 5urface sampled of 52 Entic Haplustolls under three diferents uses (24 under continuous cultivation), 18 under rotation wuth grass Ieys (R), and 10 virgin soils M were analyzed for c1ay, silt, organic malter anrd water content, bulk density, compaction and aggregate stability. Data were analyzed statistically using principal components, canonical variables, and discriminant functions. A satisfactory segregation of the soils according to discriminant properties (coarse organic matter, aggregate stability, and suceptibility lo compaction) was obtained. The model developed satisfactory classified the soils under different uses (100% R, 83% e, and 88% V). Principal component analysis also showed that bulck density, compaction, and wet aggregate salability are related lo organic matter content. We conclude that, in the studied region, the lower the ratio of organic matter lo clay + soil content, the more severe the physical deterioration of the soils.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.)Publicado en Soil Science, Vol 163 N°7
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