334 research outputs found
Non-Gaussian states by conditional measurements
We address realistic schemes for the generation of non-Gaussian states of
light based on conditional intensity measurements performed on correlated
bipartite states. We consider both quantum and classically correlated states
and different kind of detection, comparing the resulting non Gaussianity
parameters upon varying the input energy and the detection efficiency. We find
that quantum correlations generally lead to higher non Gaussianity, at least in
the low energy regime. An experimental implementation feasible with current
technology is also suggested.Comment: 8 pages, 3 figure
Conditional measurements on multimode pairwise entangled states from spontaneous parametric downconversion
We address the intrinsic multimode nature of the quantum state of light
obtained by pulsed spontaneous parametric downconversion and develop a
theoretical model based only on experimentally accessible quantities. We
exploit the pairwise entanglement as a resource for conditional multimode
measurements and derive closed formulas for the detection probability and the
density matrix of the conditional states. We present a set of experiments
performed to validate our model in different conditions that are in excellent
agreement with experimental data. Finally, we evaluate nonGaussianity of the
conditional states obtained from our source with the aim of discussing the
effects of the different experimental parameters on the efficacy of this type
of conditional state preparation
Robust generation of entanglement in Bose-Einstein condensates by collective atomic recoil
We address the dynamics induced by collective atomic recoil in a
Bose-Einstein condensate in presence of radiation losses and atomic
decoherence. In particular, we focus on the linear regime of the lasing
mechanism, and analyze the effects of losses and decoherence on the generation
of entanglement. The dynamics is that of three bosons, two atomic modes
interacting with a single-mode radiation field, coupled with a bath of
oscillators. The resulting three-mode dissipative Master equation is solved
analytically in terms of the Wigner function. We examine in details the two
complementary limits of {\em high-Q cavity} and {\em bad-cavity}, the latter
corresponding to the so-called superradiant regime, both in the quasi-classical
and quantum regimes. We found that three-mode entanglement as well as two-mode
atom-atom and atom-radiation entanglement is generally robust against losses
and decoherence,thus making the present system a good candidate for the
experimental observation of entanglement in condensate systems. In particular,
steady-state entanglement may be obtained both between atoms with opposite
momenta and between atoms and photons
Reliable source of conditional non-Gaussian states from single-mode thermal fields
We address both theoretically and experimentally the generation of pulsed
non-Gaussian states from classical Gaussian ones by means of conditional
measurements. The setup relies on a beam splitter and a pair of linear
photodetectors able to resolve up to tens of photons in the two outputs. We
show the reliability of the setup and the good agreement with the theory for a
single-mode thermal field entering the beam splitter and present a thorough
characterization of the photon statistics of the conditional states.Comment: 18 pages, 12 figure
State reconstruction by on/off measurements
We demonstrate a state reconstruction technique which provides either the
Wigner function or the density matrix of a field mode and requires only
avalanche photodetectors, without any phase or amplitude discrimination power.
It represents an alternative, of simpler implementation, to quantum homodyne
tomography.Comment: 6 pages, 4 figures, revised and enlarged versio
Generalized Nash Equilibrium and Market Coupling in the European Power System
Market Coupling'' is currently seen as the most advanced market design in the restructuring of the European electricity market. Market coupling, by construction, introduces what is generally referred to as an incomplete market: it leaves several constraints out of the market and hence avoids pricing them. This may or may not have important consequences in practice depending on the case on hand. QuasiVariational Inequality problems. We apply one of these methods to a subproblem of market coupling namely the coordination of counter-trading. This problem is an illustration of a more general question encountered for instance in hierarchical planning in production management. We first discuss the economic interpretation of the Quasi-Variational Inequality problem. We then apply the algorithmic approach to a set of stylized case studies in order to illustrate the impact of different organizations of counter-trading. The paper emphazises the structuring of the problem. A companion paper considers the full problem of market coupling and counter-trading and presents a more extensive numerical analysis
Role and Management of a Head and Neck Department during the COVID-19 Outbreak in Lombardy
The recent Italian outbreak of coronavirus disease 2019 led to an unprecedented burden on our health care system. Despite head and neck\u2013otolaryngology not being a front-line specialty in dealing with this disease, our department had to face several specific issues. Despite a massive reallocation of resources in the hospital, we managed to keep the service active, improving safety measures for our personnel, specifically during common otolaryngologic maneuvers known to produce aerosols. Furthermore, we strived to maintain our teaching role, giving residents an inclusive role in managing the response to the emergency state, and we progressively integrated our inactive specialists into other service rotations to relieve front-line colleagues\u2019 burden. Specific issues and management decisions are discussed in detail in the article
Sub-shot-noise photon-number correlation in mesoscopic twin-beam of light
We demonstrate sub-shot-noise photon-number correlations in a (temporal)
multimode mesoscopic ( detected photons) twin-beam produced by
ps-pulsed spontaneous non-degenerate parametric downconversion. We have
separately detected the signal and idler distributions of photons collected in
twin coherence areas and found that the variance of the photon-count difference
goes below the shot-noise limit by 3.25 dB. The number of temporal modes
contained in the twin-beam, as well as the size of the twin coherence areas,
depends on the pump intensity. Our scheme is based on spontaneous
downconversion and thus does not suffer from limitations due to the finite gain
of the parametric process. Twin-beams are also used to demonstrate the
conditional preparation of a nonclassical (sub-Poissonian) state.Comment: 5 pages, 5 (low-res) figures, to appear on PR
The balance of quantum correlations for a class of feasible tripartite continuous variable states
We address the balance of quantum correlations for continuous variable (CV)
states. In particular, we consider a class of feasible tripartite CV pure
states and explicitly prove two Koashi-Winter-like conservation laws involving
Gaussian entanglement of formation, Gaussian quantum discord and sub-system Von
Neumann entropies. We also address the class of tripartite CV mixed states
resulting from the propagation in a noisy environment, and discuss how the
previous equalities evolve into inequalities.Comment: Special issue "Classical Vs Quantum correlations in composite
systems" edited by L. Amico, S. Bose, V. Korepin and V. Vedral, published
versio
Demonstration of a bright and compact source of tripartite nonclassical light
We experimentally demonstrate the nonclassical photon number correlations
expected in tripartite continuous variable states obtained by parametric
processes. Our scheme involves a single nonlinear crystal, where two
interlinked parametric interactions take place simultaneously, and represents a
bright and compact source of a sub-shot-noise tripartite light field. We
analyze the effects of the pump intensities on the numbers of detected photons
and on the amount of noise reduction in some details, thus demonstrating a good
agreement between the experimental data and a single-mode theoretical
description.Comment: submitted to "Physical Review A
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