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-Λb\Lambda_b interaction

In this work we study the low energy pion-$\Lambda_b$ interaction considering effecective chiral Lagrangians that include pions, baryons and the corresponding resonances. Interactions mediated by a $\sigma$ 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