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R. de Melo e Souza

Publications and source records attributed to R. de Melo e Souza.

4 recordsLinked to original sources
arXiv2026

On the magnetic counterpart of the Uehling correction

In this work, we investigate the magnetic properties of the quantum vacuum in the context of QED. We calculate the quantum relativistic correction of virtual particle-anti-particle pair creation to the field of a classical point-like idealized magnet. Using such correction, we find the induced currents stemming from the effect of the polarization of the vacuum, which behaves like a paramagnetic medium. We also calculate the correction to the electric dipole potential and show that the well-known symmetry between the classical fields of point electric and magnetic dipoles is broken at the quantum level. Lastly, to illustrate possible applications of our findings, we briefly discuss the effect of the corrections obtained here in the context of neutron-neutron scattering and the hyperfine splitting for hydrogen-like atoms.

hep-ph↗
arXiv2026

Microscopic Quantum Friction

We report on a microscopic theory of quantum friction. Our approach investigates the interplay between the dispersive response and the relative center-of-mass motion of two ground-state atoms. This coupling yields a quantum force, which can be expressed as a power series in the velocity. The significance of each contribution depends on its order parity: while even-order terms are reversible, odd-order terms are irreversible and only survive in the presence of an internal dissipation mechanism. In addition, we obtain general, model-independent properties for the work performed by these contributions for arbitrary scattering trajectories. These results enable an unambiguous identification of odd-parity terms with microscopic quantum friction. At room temperature, the dominant microscopic quantum friction is of first order in the velocity and presents a strong quantum character. Our microscopic theory reveals that several properties of quantum friction obtained in specific settings -- such as the cubic dependence on velocity at zero temperature -- are indeed universal features already present at the atomic scale.

quant-ph↗
arXiv2025

Tailoring the van der Waals interaction with rotation

We report a systematic procedure to engineer the van der Waals force between levitated nanoparticles in high vacuum by setting them into a fast rotation. By tuning the rotation frequency close to a polaritonic resonance, we can significantly enhance the van der Waals attraction. In addition, for frequencies slightly beyond resonance, rotation can change the nature of the interaction from attraction to repulsion. Rotational Doppler shifts effectively modify the frequency-dependent polarizability of the nanoparticles, thereby reshaping their mutual interaction. As a concrete and realistic example, we consider spinning barium strontium titanate nanoparticles at state-of-the-art rotation frequencies and demonstrate a modification of the force within the sensitivity of current experimental techniques.

quant-ph↗