1,730 research outputs found
Photon blockade induced Mott transitions and XY spin models in coupled cavity arrays
As photons do not interact with each other, it is interesting to ask whether
photonic systems can be modified to exhibit the phases characteristic of
strongly coupled many-body systems. We demonstrate how a Mott insulator type of
phase of excitations can arise in an array of coupled electromagnetic cavities,
each of which is coupled resonantly to a {\em single} two level system
(atom/quantum dot/Cooper pair) and can be individually addressed from outside.
In the Mott phase each atom-cavity system has the same integral number of net
polaritonic (atomic plus photonic) excitations with photon blockade providing
the required repulsion between the excitations in each site. Detuning the
atomic and photonic frequencies suppresses this effect and induces a transition
to a photonic superfluid. We also show that for zero detuning, the system can
simulate the dynamics of many body spin systems.Comment: 4 pages, 3 figure
Geometric phase induced by a cyclically evolving squeezed vacuum reservoir
We propose a new way to generate an observable geometric phase by means of a
completely incoherent phenomenon. We show how to imprint a geometric phase to a
system by "adiabatically" manipulating the environment with which it interacts.
As a specific scheme we analyse a multilevel atom interacting with a broad-band
squeezed vacuum bosonic bath. As the squeezing parameters are smoothly changed
in time along a closed loop, the ground state of the system acquires a
geometric phase. We propose also a scheme to measure such geometric phase by
means of a suitable polarization detection.Comment: 4 pages, 1 figur
Low energy pion- interaction
In this work we study the low energy pion- interaction considering
effecective chiral Lagrangians that include pions, baryons and the
corresponding resonances. Interactions mediated by a meson exchange
are also considered. The scattering amplitudes are calculated and then we
determine the angular distributions and polarizations.Comment: 8 pages, 7 figure
Coherent evolution via reservoir driven holonomy
We show that in the limit of strongly interacting environment a system
initially prepared in a Decoherence Free Subspace (DFS) coherently evolves in
time, adiabatically following the changes of the DFS. If the reservoir cyclicly
evolves in time, the DFS states acquire an holonomy.Comment: 4 page
Equilibrium and Disorder-induced behavior in Quantum Light-Matter Systems
We analyze equilibrium properties of coupled-doped cavities described by the
Jaynes-Cummings- Hubbard Hamiltonian. In particular, we characterize the
entanglement of the system in relation to the insulating-superfluid phase
transition. We point out the existence of a crossover inside the superfluid
phase of the system when the excitations change from polaritonic to purely
photonic. Using an ensemble statistical approach for small systems and
stochastic-mean-field theory for large systems we analyze static disorder of
the characteristic parameters of the system and explore the ground state
induced statistics. We report on a variety of glassy phases deriving from the
hybrid statistics of the system. On-site strong disorder induces insulating
behavior through two different mechanisms. For disorder in the light-matter
detuning, low energy cavities dominate the statistics allowing the excitations
to localize and bunch in such cavities. In the case of disorder in the light-
matter coupling, sites with strong coupling between light and matter become
very significant, which enhances the Mott-like insulating behavior. Inter-site
(hopping) disorder induces fluidity and the dominant sites are strongly coupled
to each other.Comment: about 10 pages, 12 figure
Not every edible orange milkcap is Lactarius deliciosus: first record of Lactarius quieticolor (sect. Deliciosi) from Brazil
The natural distribution of species of Lactarius sect. Deliciosi is mainly in the northern hemisphere, where they grow in ectomycor-rhizal symbiosis mainly with conifers. Several species in this sec-tion are regionally well known and appreciated due to their culinary use. In South America, there is limited knowledge of their presence and harvesting, while their culinary value remains underexploited. Recently, field campaigns in pine plantations in southern Brazil revealed wide presence of Lactarius sect. Deliciosi species. Morpho-logical and molecular identification approaches confirmed that all Brazilian collections correspond to one European species, Lactarius quieticolor. Fruiting bodies occurred in plantations of Pinus taeda and/or P. elliottii, on acidic soils, and under humid climate with mild to hot summers. A review of edibility and organoleptic properties confirmed both L. quieticolor and its commonly misapplied name, L. deliciosus, in South America as edible and of high quality. Several other L. sect. Deliciosi species are less appreciated or with unknown palatability. Due to low potential for long-distance dispersal, an ecto-mycorrhizal partner switch from European to North American pine species is proposed, which may have happened in South America for both allochthonous symbiotic partners. There is still a possibility that other combinations were established, including combinations with less valuable species from L. sect. Deliciosi
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