The Role of Fermions in Bubble Nucleation

We present a study of the role of fermions in the decay of metastable states of a scalar field via bubble nucleation. We analyze both one and three-dimensional systems by using a gradient expansion for the calculation of the fermionic determinant. The results of the one-dimensional case are compared to the exact results of previous work.Comment: 15 pages, revtex, 9 figure

Holonomy Transformation in the FRW Metric

In this work we investigate loop variables in Friedman-Robertson-Walker spacetime. We analyze the parallel transport of vectors and spinors in several paths in this spacetime in order to classify its global properties. The band holonomy invariance is analysed in this background.Comment: 8 page

Fast gates for ion traps by splitting laser pulses

We present a fast phase gate scheme that is experimentally achievable and has an operation time more than two orders of magnitude faster than current experimental schemes for low numbers of pulses. The gate time improves with the number of pulses following an inverse power law. Unlike implemented schemes which excite precise motional sidebands, thus limiting the gate timescale, our scheme excites multiple motional states using discrete ultra-fast pulses.We use beam-splitters to divide pulses into smaller components to overcome limitations due to the finite laser pulse repetition rate. This provides gate times faster than proposed theoretical schemes when we optimize a practical setup

Phase-space reconstruction of an atomic chaotic system

We consider the dynamics of a single atom submitted to periodic pulses of a far-detuned standing wave generated by a high-finesse optical cavity, which is an atomic version of the well-known ``kicked rotor''. We show that the classical phase-space map can be ``reconstructed'' by monitoring the transmission of the cavity. We also studied the effect of spontaneous emission on the reconstruction, and put limits to the maximum acceptable spontaneous emission rate.Comment: 5 figures, submitted to PR

Power-law statistics and stellar rotational velocities in the Pleiades

In this paper we will show that, the non-gaussian statistics framework based on the Kaniadakis statistics is more appropriate to fit the observed distributions of projected rotational velocity measurements of stars in the Pleiades open cluster. To this end, we compare the results from the $\kappa$ and $q$-distributions with the Maxwellian.Comment: 13 pages, 3 figure