High Frequency Quantum Admittance and Noise Measurement with an On-chip Resonant Circuit

By coupling a quantum detector, a superconductor-insulator-superconductor junction, to a Josephson junction \textit{via} a resonant circuit we probe the high frequency properties, namely the ac complex admittance and the current fluctuations of the Josephson junction at the resonant frequencies. The admittance components show frequency dependent singularities related to the superconducting density of state while the noise exhibits a strong frequency dependence, consistent with theoretical predictions. The circuit also allows to probe separately the emission and absorption noise in the quantum regime of the superconducting resonant circuit at equilibrium. At low temperature the resonant circuit exhibits only absorption noise related to zero point fluctuations, whereas at higher temperature emission noise is also present.Comment: 15 pages, 15 figure

Decidability Results for Multi-objective Stochastic Games

We study stochastic two-player turn-based games in which the objective of one player is to ensure several infinite-horizon total reward objectives, while the other player attempts to spoil at least one of the objectives. The games have previously been shown not to be determined, and an approximation algorithm for computing a Pareto curve has been given. The major drawback of the existing algorithm is that it needs to compute Pareto curves for finite horizon objectives (for increasing length of the horizon), and the size of these Pareto curves can grow unboundedly, even when the infinite-horizon Pareto curve is small. By adapting existing results, we first give an algorithm that computes the Pareto curve for determined games. Then, as the main result of the paper, we show that for the natural class of stopping games and when there are two reward objectives, the problem of deciding whether a player can ensure satisfaction of the objectives with given thresholds is decidable. The result relies on intricate and novel proof which shows that the Pareto curves contain only finitely many points. As a consequence, we get that the two-objective discounted-reward problem for unrestricted class of stochastic games is decidable.Comment: 35 page

On generation of metric perturbations during preheating

We consider the generation of the scalar mode of the metric perturbations during preheating stage in a two field model with the potential $V(\phi, \chi)= {m^{2}\phi^{2}\over 2}+{g^{2}\phi^{2}\chi^{2}\over 2}$. We discuss two possible sources of such perturbations: a) due to the coupling between the perturbation of the matter field $\delta \chi$ and the background part of the matter field $\chi_{0}(t)$, b) due to non-linear fluctuations in a condensate of ``particles'' of the field $\chi$. Both types of the metric perturbations are assumed to be small, and estimated using the linear theory of the metric perturbations. We estimate analytically the upper limit of the amplitude of the metric perturbations for all scales in the limit of so-called broad resonance, and show that the large scale metric perturbations are very small, and taking them into account does not influence the standard picture of the production of the metric perturbations in inflationary scenario.Comment: This version is to be published in PRD, new references added and typos correcte

Relación sencilla de los obsequios que la Ilma. Diputación del Reino de Navarra y sus pueblos del tránsito han tributado a sus ... Soberanos Don Fernando III de Navarra, VII de Castilla, y Doña María Josefa Amalia de Sajonia

Texto firmado por José Basse

An entomocentric view of the Janzen-Connell hypothesis

In 1987, in the first issue of Conservation Biology, Edward O. Wilson wrote about the “little things that run the world” – the importance and conservation of insects (Wilson, 1987). Readers of Insect Conservation and Diversity will no doubt be very familiar with the concept. Sadly, however, this perception is not as widely shared among the rest of the scientific community as it should be, and insects are still comparatively neglected as a prime focus of scientific investigations