arXiv subjects

M. Donaire

Publications and source records attributed to M. Donaire.

23 records · Page 2Linked to original sources

arXiv2009

Dipole emission and coherent transport in random media II. Density of states vs. index of refraction

This is the second of a series of papers devoted to develop a microscopical approach to the dipole emission process and its relation to coherent transport in random media. In this Letter, we deduce a relation between the transverse decay rate of an emitter in a virtual cavity and the complex refraction index of the host medium. We argue on the possibility of a criterion for inhibition/enhancement of spontaneous emission in function of the transition frequency and the correlation length of the host scatterers. In addition, we study the radiative/non-radiative nature of the net power emission through a microscopical analysis of the scattering events involved. This study reveals essential discrepancies with previous interpretations.

physics.optics↗

arXiv2009

Dipole emission and coherent transport in random media III. Emission from a real cavity in a continuous medium

This is the third of a series of papers devoted to develop a microscopical approach to the dipole emission process and its relation to coherent transport in random media. In this paper, we compute the power emitted by an induced dipole and the spontaneous decay rate of a Lorentzian-type dipole. In both cases, the emitter is placed at the center of a real cavity drilled in a continuous medium.

physics.optics↗

arXiv2008

On the density of states and extinction mean free path of waves in random media: Dispersion relations and sum rules

We establish a fundamental relationship between the averaged density of states and the extinction mean free path of wave propagating in random media. From the principle of causality and the Kramers-Kronig relations, we show that both quantities are connected by dispersion relations and are constrained by a frequency sum rule. The results are valid under very general conditions and should be helpful in the analysis of measurements of wave transport through complex systems and in the design of randomly or periodically structured materials with specific transport properties.

cond-mat.dis-nn↗

arXiv2006

Heavy cosmic strings

We argue that cosmic strings with high winding numbers generally form in first-order gauge symmetry breaking phase transitions, and we demonstrate this using computer simulations. These strings are heavier than single-winding strings and therefore more easily observable. Their cosmological evolution may also be very different.

hep-ph↗

arXiv2004

Spontaneous vortex formation on a superconductor film

We carry out numerical simulations to investigate spontaneous vortex formation during a temperature quench of a superconductor film from the normal to the superconducting phase in the absence of an external magnetic field. Our results agree roughly with quantitative predictions of the flux trapping scenario: In fast quenches the agreement is almost perfect, but there appears to be some discrepancy in slower ones. In particular, our simulations demonstrate the crucial role the electromagnetic field plays in this phenomenon, making it very different from vortex formation in superfluids. Besides superconductor experiments, our findings also shed more light on the possible formation of cosmic defects in the early universe.

cond-mat.supr-con↗