Light dressed-excitons in an incoherent-electron sea: Evidence for Mollow-triplet and Autler-Townes doublet

We demonstrate that the interaction between excitons and a sea of incoherent electrons does not preclude excitons dressing by light. We investigate the role of exciton-electron scattering in the light dressing by measuring the dynamical absorption spectrum of a modulation-doped CdTe quantum well, which shows a clear evidence for significant electron scattering of the excitonic states. We show the occurrence of dressed and correlated excitons by detecting quantum coherent interferences through excitonic Autler-Townes doublet and ac Stark splitting, which evolves to Mollow triplet with gain. We also evidence the partial inhibition of the electron-exciton scattering by exciton-light coupling

Increasing power-law range in avalanche amplitude and energy distributions

Power-law type probability density functions spanning several orders of magnitude are found for different avalanche properties. We propose a methodology to overcome empirical constrains that limit the power-law range for the distributions of different avalanche observables like amplitude, energy, duration or size. By considering catalogs of events that cover different observation windows, maximum likelihood estimation of a global power-law exponent is computed. This methodology is applied to amplitude and energy distributions of acoustic emission avalanches in failure-under- compression experiments of a nanoporous silica glass, finding in some cases global exponents in an unprecedented broad range: 4.5 decades for amplitudes and 9.5 decades for energies. In the later case, however, strict statistical analysis suggests experimental limitations might alter the power-law behavior.Comment: 23 pages, 7 figure

Desmame aos 60 dias: um instrumento de manejo para capacitar a matriz a repetir cria.

bitstream/item/63453/1/it11-2000.pd

Avalanches in the athermal 2d Random-Field Ising model: front propagation versus nucleation and growth dynamics

Màster Oficial en Física Avançada, , Facultat de Física, Universitat de Barcelona, Curs: 2015, Tutor: Eduard Vives i Santa-EulaliaThe two-dimensional zero-temperature Random Field Ising Model with local adiabatic relaxation dynamics is studied. When externally driven, this model allows to analyse the properties of an advancing front for different amounts of disorder. By imposing special forced boundary conditions and allowing for systems with rectangular geometry, we favour the existence of a unique interface which is the boundary of a 1d spanning avalanche. We show that the description of an advancing front in terms of a univalued function x(y) lacks of a relevant contribution in the thermodynamic limit: the existence of overhangs and islands which are characteristic of the nucleation and growth dynamic

Quality of life in temporomandibular dysfunction patients: assessment by SF-36 questionnaire

BV UNIFESP: Teses e dissertaçõe

The Barkhausen Effect

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2014, Tutor: Eduard Vives i Santa-EulàliaThis work presents an introduction to the Barkhausen e ect. First, experimental measurements of Barkhausen noise detected in a soft iron sample will be exposed and analysed. Two di erent kinds of simulations of the 2-d Out of Equilibrium Random Field Ising Model (RFIM) at T=0 will be performed in order to explain this e ect: one with periodic boundary conditions (PBC) and the other with xed boundary conditions (FBC). The rst model represents a spin nucleation dynamics whereas the second one represents the dynamics of a single domain wall. Results from these two di erent models will be contrasted and discussed in order to understand the nature of this e ect