7,506 research outputs found
Combined quantum state preparation and laser cooling of a continuous beam of cold atoms
We use two-laser optical pumping on a continuous atomic fountain in order to
prepare cold cesium atoms in the same quantum ground state. A first laser
excites the F=4 ground state to pump the atoms toward F=3 while a second
pi-polarized laser excites the F=3 -> F'=3 transition of the D2 line to produce
Zeeman pumping toward m=0. To avoid trap states, we implement the first laser
in a 2D optical lattice geometry, thereby creating polarization gradients. This
configuration has the advantage of simultaneously producing Sisyphus cooling
when the optical lattice laser is tuned between the F=4 -> F'=4 and F=4 -> F'=5
transitions of the D2 line, which is important to remove the heat produced by
optical pumping. Detuning the frequency of the second pi-polarized laser
reveals the action of a new mechanism improving both laser cooling and state
preparation efficiency. A physical interpretation of this mechanism is
discussed.Comment: Minor changes according to the recommendations of the referee: -
Corrected Fig.1. - Split the graph of Fig.6 for clarity. - Added one
reference. - Added two remarks in the conclusion. - Results unchange
La valutazione del merito creditizio in agricoltura alla luce dell’Accordo Basilea 2: un applicazione ad un’impresa floricola
The markets’ globalisation induces the national agriculture sector to improve its competitiveness by structural adjustment of the farms. This process requires financial resources so that new and more intensive relations will be necessary between bank and farm. From this point of view the new agreement named Basilea 2 is seen as a potential threat that may reduce the capability to credit access for the agricultural entrepreneurs. For this reason this study has verified the principal aspects that will influence the assessment of the farms’ rating by applying the procedure in a floricultural farm. A sensitive analysis has been developed in order to evaluate if the new agreement constitutes a threat or an opportunity for the farm in receiving funds from the bank
Strongly correlated double Dirac fermions
Double Dirac fermions have recently been identified as possible
quasiparticles hosted by three-dimensional crystals with particular
non-symmorphic point group symmetries. Applying a combined approach of
ab-initio methods and dynamical mean field theory, we investigate how
interactions and double Dirac band topology conspire to form the electronic
quantum state of BiCuO. We derive a downfolded eight-band model of the
pristine material at low energies around the Fermi level. By tuning the model
parameters from the free band structure to the realistic strongly correlated
regime, we find a persistence of the double Dirac dispersion until its
constituting time reveral symmetry is broken due to the onset of magnetic
ordering at the Mott transition. We analyze pressure as a promising route to
realize a double-Dirac metal in BiCuO
Hamilton-Jacobi approach to Potential Functions in Information Geometry
The search for a potential function allowing to reconstruct a given
metric tensor and a given symmetric covariant tensor on a manifold
is formulated as the Hamilton-Jacobi problem associated with a
canonically defined Lagrangian on . The connection between this
problem, the geometric structure of the space of pure states of quantum
mechanics, and the theory of contrast functions of classical information
geometry is outlined.Comment: 16 pages. A discussion on the Kullback-Leibler divergence has been
added. To appear in Journal of Mathematical Physic
Caccia alle “cimici” aliene: il ruolo del disinfestatore
Vengono descritte le linee guida sul comportamento da tenere da parte di cittadini e disinfestatori nel caso di infestazioni da cimici asiatiche Halyomorpha halys dentro alle abitazion
Commentary: primary emotional systems and personality: an evolutionary perspective
In Primary emotional systems and personality Christian Montag and Jaak Panksepp analyze how emotional systems are involved into the development of basic personality into an evolutionary framework. They also stress the importance of such investigation for the promotion of human welfare in the context of psychiatric research and practic
Nonlocal and nonlinear effects in hyperbolic heat transfer in a two-temperature model
AbstractThe correct analysis of heat transport at nanoscale is one of the main reasons of new developments in physics and nonequilibrium thermodynamic theories beyond the classical Fourier law. In this paper, we provide a two-temperature model which allows to describe the different regimes which electrons and phonons can undergo in the heat transfer phenomenon. The physical admissibility of that model is showed in view of second law of thermodynamics. The above model is applied to study the propagation of heat waves in order to point out the special role played by nonlocal and nonlinear effects
Are collapse models testable with quantum oscillating systems? The case of neutrinos, kaons, chiral molecules
Collapse models provide a theoretical framework for understanding how
classical world emerges from quantum mechanics. Their dynamics preserves
(practically) quantum linearity for microscopic systems, while it becomes
strongly nonlinear when moving towards macroscopic scale. The conventional
approach to test collapse models is to create spatial superpositions of
mesoscopic systems and then examine the loss of interference, while
environmental noises are engineered carefully. Here we investigate a different
approach: We study systems that naturally oscillate --creating quantum
superpositions-- and thus represent a natural case-study for testing quantum
linearity: neutrinos, neutral mesons, and chiral molecules. We will show how
spontaneous collapses affect their oscillatory behavior, and will compare them
with environmental decoherence effects. We will show that, contrary to what
previously predicted, collapse models cannot be tested with neutrinos. The
effect is stronger for neutral mesons, but still beyond experimental reach.
Instead, chiral molecules can offer promising candidates for testing collapse
models.Comment: accepted by NATURE Scientific Reports, 12 pages, 1 figures, 2 table
Aspects of geodesical motion with Fisher-Rao metric: classical and quantum
The purpose of this article is to exploit the geometric structure of Quantum
Mechanics and of statistical manifolds to study the qualitative effect that the
quantum properties have in the statistical description of a system. We show
that the end points of geodesics in the classical setting coincide with the
probability distributions that minimise Shannon's Entropy, i.e. with
distributions of zero dispersion. In the quantum setting this happens only for
particular initial conditions, which in turn correspond to classical
submanifolds. This result can be interpreted as a geometric manifestation of
the uncertainty principle.Comment: 15 pages, 5 figure
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