arXiv subjects

T. D. Ferreira

Publications and source records attributed to T. D. Ferreira.

2 recordsLinked to original sources

arXiv2026

Three-observable measurement of the critical velocity in a paraxial superfluid of light flowing past a mobile impurity

We report the measurement of the critical velocity of a paraxial superfluid of light flowing past a mobile impurity, realized using a dual-wavelength optical scheme in a warm vapor of $^{87}\text{Rb}$. The superflow is two-dimensional by nature, while the impurity features a highly repulsive potential, a large tunable radius, and a finite mass. The critical velocity is evaluated by simultaneously monitoring three complementary observables: the number of vortices nucleated in the wake of the impurity, the hydrodynamic force exerted on it, and its displacement velocity relative to the flow. These independent methods yield consistent values for the critical velocity, which remain systematically below the Landau criterion and decrease with the impurity radius, in qualitative agreement with theoretical expectations. Our results demonstrate the reliability of these combined diagnostics, establishing paraxial superfluids of light as a versatile platform for exploring the impurity problem in quantum hydrodynamics.

cond-mat.quant-gas↗

arXiv2021

Pressureless stationary solutions in a Newton-Yukawa gravity model

Non-minimally coupled curvature-matter gravity models are an interesting alternative to the Theory of General Relativity and to address the dark energy and dark matter cosmological problems. These models have complex field equations that prevent a full analytical study. Nonetheless, in a particular limit, the behavior of a matter distribution can, in these models, be described by a Schrödinger-Newton system. In nonlinear optics, the Schrödinger-Newton system can be used to tackle a wide variety of relevant situations and several numerical tools have been developed for this purpose. Interestingly, these methods can be adapted to study General Relativity problems as well as its extensions. In this work, we report the use of these numerical tools to study a particular non-minimal coupling model that introduces two new potentials, an attractive Yukawa potential and a repulsive potential proportional to the energy density. Using the imaginary-time propagation method we have shown that stationary solutions arise even at low energy density regimes.

gr-qc↗