Influence of the pair coherence on the charge tunneling through a quantum dot connected to a superconducting lead

We analyze the charge transport through a single level quantum dot coupled to a normal (N) and superconducting (S) leads where the electron pairs exist either as the coherent (for temperatures below T_c) or incoherent objects (in a region T_c < T < T*). This situation can be achieved in practice if one uses the high T_c superconducting material where various precursor effects have been observed upon approaching $T_{c}$ from above. Without restricting to any particular microscopic mechanism we investigate some qualitative changes of the nonequilibrium charge current caused by the electron pair coherence.Comment: 7 pages, 9 figure

Quantum MERA Channels

Tensor networks representations of many-body quantum systems can be described in terms of quantum channels. We focus on channels associated with the Multi-scale Entanglement Renormalization Ansatz (MERA) tensor network that has been recently introduced to efficiently describe critical systems. Our approach allows us to compute the MERA correspondent to the thermodynamic limit of a critical system introducing a transfer matrix formalism, and to relate the system critical exponents to the convergence rates of the associated channels.Comment: 4 pages, 2 figure

Entanglement Content of Quantum Particle Excitations II. Disconnected Regions and Logarithmic Negativity

In this paper we study the increment of the entanglement entropy and of the (replica) logarithmic negativity in a zero-density excited state of a free massive bosonic theory, compared to the ground state. This extends the work of two previous publications by the same authors. We consider the case of two disconnected regions and find that the change in the entanglement entropy depends only on the combined size of the regions and is independent of their connectivity. We subsequently generalize this result to any number of disconnected regions. For the replica negativity we find that its increment is a polynomial with integer coefficients depending only on the sizes of the two regions. The logarithmic negativity turns out to have a more complicated functional structure than its replica version, typically involving roots of polynomials on the sizes of the regions. We obtain our results by two methods already employed in previous work: from a qubit picture and by computing four-point functions of branch point twist fields in finite volume. We test our results against numerical simulations on a harmonic chain and find excellent agreement

Proposal for a Precision Measurement of |Vub|

A new method for a precision measurement of the CKM matrix element |Vub| is discussed, which combines good theoretical control with high efficiency and a powerful discrimination against charm background. The resulting combined theoretical uncertainty on |Vub| is estimated to be 10%.Comment: 4 pages, 2 figures, RevTe

Signatures of the super fluid-insulator phase transition in laser driven dissipative nonlinear cavity arrays

We analyze the non-equilibrium dynamics of a gas of interacting photons in an array of coupled dissipative nonlinear cavities driven by a pulsed external coherent field. Using a mean-field approach, we show that the system exhibits a phase transition from a Mott-insulator-like to a superfluid regime. For a given single-photon nonlinearity, the critical value of the photon tunneling rate at which the phase transition occurs increases with the increasing photon loss rate. We checked the robustness of the transition by showing its insensitivity to the initial state prepared by the the pulsed excitation. We find that the second-order coherence of cavity emission can be used to determine the phase diagram of an optical many-body system without the need for thermalization.Comment: 4 pages, 4 figure

Crossed Andreev reflection-induced magnetoresistance

We show that very large negative magnetoresistance can be obtained in magnetic trilayers in a current-in-plane geometry owing to the existence of crossed Andreev reflection. This spin-valve consists of a thin superconducting film sandwiched between two ferromagnetic layers whose magnetization is allowed to be either parallelly or antiparallelly aligned. For a suitable choice of structure parameters and nearly fully spin-polarized ferromagnets the magnetoresistance can exceed -80%. Our results are relevant for the design and implementation of spintronic devices exploiting ferromagnet-superconductor structures.Comment: 5 pages, 4 figures, final published versio

Antibiotic susceptibility of bacterial isolates from probiotic products available in Italy

Objective: An emerging issue of probiotic products is the antibiotic resistance of the strains used. The aim of this study was to determine the susceptibility of the isolates of 10 probiotic products available in Italy. Materials and methods: The susceptibility of 15 strains of Lactobacillus spp., 5 Streptococcus salivarius ssp. thermophilus, 1 Enterococcus faecium and 8 Bifidobacterium spp. to several groups of antibacterial agents was determined by E-test using MRS agar for Lactobacillus spp. and E. faecium and MH agar+5% sheep blood for S. thermophilus, with different conditions of incubation. For Lactobacillus, S. thermophilus and E. faecium the MICs obtained by E-test were compared to the MICs by broth microdilution test obtained following CLSI M45-A (2006) and CLSI M100-S17 (2007) guidelines. Results: The broth microdilution test resulted in MICs identical to those obtained with the E-test or in MICs with differences of 1 or 2 log dilution steps. All the strains of Lactobacillus were susceptible to ampicillin. Species-dependent antibiotic susceptibility was detected for cephalosporins; gentamicin and ciprofloxacin had variable activity. Intrinsic resistance to vancomycin was confirmed for L. paracasei, L. salivarius and L. plantarum. Atypical resistance to erythromycin was detected in one strain of L. salivarius. The strains of Bifidobacterium were susceptible to ampicillin, cefotaxime and erythromycin. The strains of E. faecium were susceptible to the tested antibiotics; the strain of S. thermophilus was resistant only to ciprofloxacin. The observed resistance in the strains used in the Italian probiotic products tested seemed to be intrinsic except for erythromycin in one L. salivarius strain.Key words: antibiotic susceptibility, probiotic, lactic acid bacteria, bifidobacteri

Attitude Accessiblity as a Determinant of Object Construal and Evaluation

Attitude accessibility, the ease with which a given attitude comes to mind, has been demonstrated to affect attention. The current experiments focus on the construal of multiply-categorizable objects. They seek to provide evidence that (a) construals toward which individuals have more accessible attitudes, i.e., those that are more attitude-evoking, are more likely to influence the evaluation of related objects and that (b) this effect of attitude accessibility on construal processes can be extended to a whole series of objects which vary along multiple dimensions. Experiment 1 provides evidence that construals whose related attitudes were made more accessible via attitude rehearsal were more likely to influence the evaluation of a related target. Experiments 2 and 3 extend these findings to the domain of foods, which vary along two potential construal continua (healthiness versus tastiness), and demonstrate that if participant attitudes toward fitness are made more accessible, participants’ judgments about eating a variety of specific foods are guided more by the healthiness of the foods

Angular anisotropy of the fusion-fission and quasifission fragments

The anisotropy in the angular distribution of the fusion-fission and quasifission fragments for the $^{16}$O+$^{238}$U, $^{19}$F+$^{208}$Pb and $^{32}$S+$^{208}$Pb reactions is studied by analyzing the angular momentum distributions of the dinuclear system and compound nucleus which are formed after capture and complete fusion, respectively. The orientation angles of axial symmetry axes of colliding nuclei to the beam direction are taken into account for the calculation of the variance of the projection of the total spin onto the fission axis. It is shown that the deviation of the experimental angular anisotropy from the statistical model picture is connected with the contribution of the quasifission fragments which is dominant in the $^{32}$S+$^{208}$Pb reaction. Enhancement of anisotropy at low energies in the $^{16}$O+$^{238}$U reaction is connected with quasifission of the dinuclear system having low temperature and effective moment of inertia.Comment: 17 pages 8 figures. Submitted to Euro. Phys. Jour.

Adiabatic pumping through interacting quantum dots

We present a general formalism to study adiabatic pumping through interacting quantum dots. We derive a formula that relates the pumped charge to the local, instantaneous Green function of the dot. This formula is then applied to the infinite-U Anderson model both for weak and strong tunnel-coupling strengths.Comment: 4 pages, 3 figure