Interqubit coupling mediated by a high-excitation-energy quantum object

We consider a system composed of two qubits and a high-excitation-energy quantum object used to mediate coupling between the qubits. We treat the entire system quantum mechanically and analyze the properties of the eigenvalues and eigenstates of the total Hamiltonian. After reproducing well-known results concerning the leading term in the mediated coupling, we obtain an expression for the residual coupling between the qubits in the off state. We also analyze the entanglement between the three objects, i.e. the two qubits and the coupler, in the eigenstates of the total Hamiltonian. Although we focus on the application of our results to the recently realized parametric-coupling scheme with two qubits, we also discuss extensions of our results to harmonic-oscillator couplers, couplers that are near resonance with the qubits and multi-qubit systems. In particular, we find that certain errors that are absent for a two-qubit system arise when dealing with multi-qubit systems.Comment: 15 pages (two-column

Phase transition in a chain of quantum vortices

We consider interacting vortices in a quasi-one-dimensional array of Josephson junctions with small capacitance. If the charging energy of a junction is of the order of the Josephson energy, the fluctuations of the superconducting order parameter in the system are considerable, and the vortices behave as quantum particles. Their density may be tuned by an external magnetic field, and therefore one can control the commensurability of the one-dimensional vortex lattice with the lattice of Josephson junctions. We show that the interplay between the quantum nature of a vortex, and the long-range interaction between the vortices leads to the existence of a specific commensurate-incommensurate transition in a one-dimensional vortex lattice. In the commensurate phase an elementary excitation is a soliton, with energy separated from the ground state by a finite gap. This gap vanishes in the incommensurate phase. Each soliton carries a fraction of a flux quantum; the propagation of solitons leads to a finite resistance of the array. We find the dependence of the resistance activation energy on the magnetic field and parameters of the Josephson array. This energy consists of the above-mentioned gap, and also of a boundary pinning term, which is different in the commensurate and incommensurate phases. The developed theory allows us to explain quantitatively the available experimental data.Comment: 14 pages, 7 eps figure

English in product advertisements in non-english speaking countries in western europe: Product image and comprehension of the text

Although English has been shown to be the most frequently used foreign language in product advertisements in countries where it is not the native language, little is known about its effects. This article examines the response to advertisements in English compared to the response to the same ad in the local language in Western Europe on members of the target group for which the ad was intended: 715 young, highly educated female consumers. The use of English in a product ad does not appear to have any impact on image and price of the product, but it does affect text comprehension: the meaning of almost 40% of the English phrases was not understood. These results were the same for all countries involved in the study, irrespective of whether the respondents\u27 (self-) reported proficiency in English is high or low. © Taylor & Francis Group, LLC

Quantum phase slip phenomenon in ultra-narrow superconducting nanorings

The smaller the system, typically - the higher is the impact of fluctuations. In narrow superconducting wires sufficiently close to the critical temperature Tc thermal fluctuations are responsible for the experimentally observable finite resistance. Quite recently it became possible to fabricate sub-10 nm superconducting structures, where the finite resistivity was reported within the whole range of experimentally obtainable temperatures. The observation has been associated with quantum fluctuations capable to quench zero resistivity in superconducting nanowires even at temperatures T-->0. Here we demonstrate that in tiny superconducting nanorings the same phenomenon is responsible for suppression of another basic attribute of superconductivity - persistent currents - dramatically affecting their magnitude, the period and the shape of the current-phase relation. The effect is of fundamental importance demonstrating the impact of quantum fluctuations on the ground state of a macroscopically coherent system, and should be taken into consideration in various nanoelectronic applications.Comment: 20 pages, 4 figure

Phase-slip induced dissipation in an atomic Bose-Hubbard system

Phase slips play a primary role in dissipation across a wide spectrum of bosonic systems, from determining the critical velocity of superfluid helium to generating resistance in thin superconducting wires. This subject has also inspired much technological interest, largely motivated by applications involving nanoscale superconducting circuit elements, e.g., standards based on quantum phase-slip junctions. While phase slips caused by thermal fluctuations at high temperatures are well understood, controversy remains over the role of phase slips in small-scale superconductors. In solids, problems such as uncontrolled noise sources and disorder complicate the study and application of phase slips. Here we show that phase slips can lead to dissipation for a clean and well-characterized Bose-Hubbard (BH) system by experimentally studying transport using ultra-cold atoms trapped in an optical lattice. In contrast to previous work, we explore a low velocity regime described by the 3D BH model which is not affected by instabilities, and we measure the effect of temperature on the dissipation strength. We show that the damping rate of atomic motion-the analogue of electrical resistance in a solid-in the confining parabolic potential fits well to a model that includes finite damping at zero temperature. The low-temperature behaviour is consistent with the theory of quantum tunnelling of phase slips, while at higher temperatures a cross-over consistent with the transition to thermal activation of phase slips is evident. Motion-induced features reminiscent of vortices and vortex rings associated with phase slips are also observed in time-of-flight imaging.Comment: published in Nature 453, 76 (2008

Inflation, moduli (de)stabilization and supersymmetry breaking

We study the cosmological inflation from the viewpoint of the moduli stabilization. We study the scenario that the superpotential has a large value during the inflation era enough to stabilize moduli, but it is small in the true vacuum. This scenario is discussed by using a simple model, one type of hybrid models.Comment: 17 pages, 7 figure

Adult Patients with Congenital Adrenal Hyperplasia Have Elevated Blood Pressure but Otherwise a Normal Cardiovascular Risk Profile

Contains fulltext : 96615.pdf (publisher's version ) (Open Access)OBJECTIVE: Treatment with glucocorticoids and mineralocorticoids has changed congenital adrenal hyperplasia (CAH) from a fatal to a chronic lifelong disease. Long-term treatment, in particular the chronic (over-)treatment with glucocorticoids, may have an adverse effect on the cardiovascular risk profile in adult CAH patients. The objective of this study was to evaluate the cardiovascular risk profile of adult CAH patients. DESIGN: Case-control study. PATIENTS AND MEASUREMENTS: In this case-control study the cardiovascular risk profile of 27 adult CAH patients and 27 controls, matched for age, sex and body mass index was evaluated by measuring ambulatory 24-hour blood pressure, insulin sensitivity (HOMA-IR), lipid profiles, albuminuria and circulating cardiovascular risk markers (PAI-1, tPA, uPA, tPA/PAI-1 complex, hsCRP, adiponectin, IL-6, IL-18 and leptin). RESULTS: 24-Hour systolic (126.3 mmHg+/-15.5 vs 124.8 mmHg+/-15.1 in controls, P = 0.019) and diastolic (76.4 mmHg+/-12.7 vs 73.5 mmHg+/-12.4 in controls, P<0.001) blood pressure was significantly elevated in CAH patients compared to the control population. CAH patients had higher HDL cholesterol levels (P<0.01), lower hsCRP levels (P = 0.03) and there was a trend toward elevated adiponectin levels compared to controls. Other cardiovascular risk factors were similar in both groups. CONCLUSION: Adult CAH patients have higher ambulatory blood pressure compared to healthy matched controls. Other cardiovascular risk markers did not differ, while HDL-cholesterol, hsCRP and adiponectin levels tended to be more favorable

The impacts of environmental warming on Odonata: a review

Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns

Enhanced Cooperation in an Asymmetric Model of Tax Competition

This paper analyzes enhanced cooperation agreements in corporate taxation in a three country tax competition model where countries differ in size. We characterize equilibrium tax rates and the optimal tax responses due to the formation of an enhanced cooperation agreement. Conditions for strategic complementarity or strategic substitutability of tax rates are crucial for the welfare effects of enhanced cooperation. Simulations show that enhanced cooperation is unlikely to be feasible for small countries. When enhanced cooperation is feasible, it may hamper global harmonization. Only when countries are of similar size is global harmonization a feasible outcome