Superconducting charge qubits from a microscopic many-body perspective

The quantised Josephson junction equation that underpins the behaviour of charge qubits and other tunnel devices is usually derived through cannonical quantisation of the classical macroscopic Josephson relations. However, this approach may neglect effects due to the fact that the charge qubit consists of a superconducting island of finite size connected to a large superconductor. We show that the well known quantised Josephson equation can be derived directly and simply from a microscopic many-body Hamiltonian. By choosing the appropriate strong coupling limit we produce a highly simplified Hamiltonian that nevertheless allows us to go beyond the mean field limit and predict further finite-size terms in addition to the basic equation.Comment: Accepted for J Phys Condensed Matte

Produção e composição química de aveia não irrigada em quatro épocas de corte.

A aveia preta e os cultivadores UPF2, UPF3 e UPF7 de aveia amarela foram avaliados durante o período de inverno, sem irrigação em Jaboticabal-SP. As plantas foram colhidas aos 51, 64, 77 e 90 dias após a semeadura. A produção de MS variou de 931,6 a 2378,3 kg/ha para aveia preta, de 903,4 a 3135,2 kg/ha para a cv. UPF2 de 439,7 a 3920,9 kg/ha para a cv. UPF3 e de 1003,7 a 4351.1 kg/ha para a cv. UPF7. Dos 51 aos 90 dias após a semeadura os teores de PB na folha decresceram, de 18,0% para 10,2%, e os de FDN aumentaram de 41,6% para 47,9%.Resumo expandid

Effect of Sowing Time on Phytomass Production during Early Growth of Two Varieties of \u3ci\u3eStylosanthes guianensis (Aubl.) Sw.\u3c/i\u3e

The objective of this research was to determine the effect of two sowing times on phytomass production of two varieties of Stylosanthes guianensis (var. pauciflora and var. vulgaris). Two experimental periods were studied (1: January - May/1998 and 2: November/1998 - March/1999) using a completely randomized factorial design 2 x 2 x 14 (two periods, two varieties and fourteen ages of evaluation), with four replications. The results showed a difference between the periods concerning the growth and development of Stylosanthes, and that period 2 was the most favourable to this forage plant. There was, also, different adaptability between the two varieties concerning the sowing times. The var. pauciflora was more adapted in period 1, and the var. vulgaris, in period 2. The data showed the possibility of selecting Stylosanthes cultivars adapted to different seasonal conditions

Allelopathy of \u3ci\u3ePanicum maximum\u3c/i\u3e Jacq. Cultivars on Tree and Shrub Forage Legumes: Greenhouse Estimate

The available information about allelopathic effects of the genus Panicum on tropical forage legumes is scarce and inconclusive. Based on this fact this research was carried out, under greenhouse conditions to evaluate potential allelopathic effects of aqueous extracts (0,10 and 20%) of three cultivars of Panicum maximum Jacq. cv. Mombaça, cv. Aruana and cv. Tanzânia-1 on three forage legumes, Leucaena leucocephala (Lam.) de Wit. (leucaena), Cajanus cajan (L.) Millsp. cv. Kaki (pigeon pea) and Sesbania sesban (L.) Merr. (sesbania) seeking for mixed grasses and legumes pastures. The following characteristics were evaluated: emergence porcentage, speed of germination index, root density, dry mass of roots, nodules, leaves and stems and leaf/stem ratio. At weekly intervals the height and leaf number of the plants were evaluated, totalising six evaluations. The results indicated that: a) the P. maximum cultivars presented allelopathic potential, that varied depending on the species of forage legume evaluated; b) the cv.Mombaça was more allelopathic to the legumes

Allelopathy of \u3ci\u3ePanicum maximum\u3c/i\u3e Jacq. Cultivars on Tree and Shrub Forage Legumes: Tolerance Index

The objective of this work was to evaluate the tolerance of three forage legumes (Leucaena leucocephala (Lam.) de Wit., Cajanus cajan (L.) Millsp. cv. Kaki and Sesbania sesban (L.) Merr.) to the allelopathic effects of three cultivars of Panicum maximum Jacq. (cv. Mombaça, cv. Aruana and cv. Tanzânia-1), under greenhouse conditions. The root and shoot tolerance indexes were calculated using the data of dry mass of roots and shoots of plants cultivated in pots and moistened with water or aqueous extracts (0,10 and 20%) of the cultivars of P. maximum. The results indicated that: a) the root tolerance index of the forage legumes was an indicator more sensitive than the shoot tolerance index, since the strongest allelopathic effects were observed in the roots; b) Sesbania was more tolerant to the grass extracts, followed by pigeon pea and leucaena, being the last the more susceptible to the grass extracts

Hydrodynamics and two-dimensional dark lump solitons for polariton superfluids

We study a two-dimensional incoherently pumped exciton-polariton condensate described by an open-dissipative Gross-Pitaevskii equation for the polariton dynamics coupled to a rate equation for the exciton density. Adopting a hydrodynamic approach, we use multiscale expansion methods to derive several models appearing in the context of shallow water waves with viscosity. In particular, we derive a Boussinesq/Benney-Luke–type equation and its far-field expansion in terms of Kadomtsev-Petviashvili-I (KP-I) equations for right- and left-going waves. From the KP-I model, we predict the existence of vorticity-free, weakly (algebraically) localized two-dimensional dark-lump solitons. We find that, in the presence of dissipation, dark lumps exhibit a lifetime three times larger than that of planar dark solitons. Direct numerical simulations show that dark lumps do exist, and their dissipative dynamics is well captured by our analytical approximation. It is also shown that lumplike and vortexlike structures can spontaneously be formed as a result of the transverse “snaking” instability of dark soliton stripes.Europe Union project AEI/FEDER: MAT2016-79866-