arXiv subjects

N. A. Moreira

Publications and source records attributed to N. A. Moreira.

3 recordsLinked to original sources

arXiv2026

Polarization-controlled transport of light in a two-dimensional waveguide

Light propagation in disordered media is particularly complex due to the interference effects and polarization-mixing terms. Two-dimensional systems are particularly interesting because they feature two decoupled scattering channels, with distinct spectral statistics due to the presence of polarization-coupling terms in only one of them. We here show that in one channel, Anderson localization bounds the light transport both longitudinally and transversely. In the second channel, in contrast, diffusive transport takes place independently of scatterer density. Our results open new possibilities for engineering of light transport in two-dimensional waveguides.

physics.optics↗

arXiv2020

Subradiance with saturated atoms: population enhancement of the long-lived states

Dipole-dipole interactions are at the origin of long-lived collective atomic states, often called subradiant, which are explored for their potential use in novel photonic devices or in quantum protocols. Here, we study subradiance beyond linear optics and experimentally demonstrate a two hundred-fold increase in the population of these modes, as the saturation parameter of the driving field is increased. We attribute this enhancement to a mechanism similar to optical pumping through the well-coupled superradiant states. The lifetimes are unaffected by the pump strength, as the system is ultimately driven toward the single-excitation sector.

physics.atom-ph↗

arXiv2019

Localization versus subradiance in three-dimensional scattering of light

We study the scattering modes of light in a three-dimensional disordered medium, in the scalar approximation and above the critical density for Anderson localization. Localized modes represent a minority of the total number of modes, even well above the threshold density, whereas spatially extended subradiant modes predominate. For specific energy ranges however, almost all modes are localized, yet adjusting accordingly the probe frequency does not allow to address these only in the regime accessible numerically. Finally, their lifetime is observed to be dominated by finite-size effects, and more specifically by the ratio of the localization length to their distance to the system boundaries.

physics.optics↗