Dynamics of electric dipoles in fluctuating light fields: From gravity-like interactions to accelerated expansion

INTRODUCTIONFluctuating isotropic electromagnetic fields are obtained by considering a large group of plane waves with wave vectors, polarizations and phases randomly distributed and fluctuating on time. Due to the isotropic... [ view full abstract ]

INTRODUCTION

Fluctuating isotropic electromagnetic fields are obtained by considering a large group of plane waves with wave vectors, polarizations and phases randomly distributed and fluctuating on time. Due to the isotropic character of this electromagnetic field, the optical force induced on an electric dipole is, in average, equal to zero. However, the dynamics of electric dipoles on these kind of systems are far from being trivial. On the one hand, due to the nonzero value of the optical force fluctuations, super diffusive, diffusive and accelerated regimens are induced on a single dipole. On the other hand, when two particles are present, the isotropic symmetry breaks down and an interacting force between the two particles shows up. This interaction may lead to gravitational like potentials.

RESULTS

In this work, the expressions for the optical random force fluctuations, the optical drag force, the equilibrium kinetic energy and mean square displacement are derived. The conditions to be fulfilled by the polarizability of the dipole in order to obtain a positive, a null, and a negative drag coefficient are analytically determined and checked against numerical simulations for the dynamics of a silver nanoparticle. Figure 1 shows a log-log plot of the mean square displacement of a silver nanoparticle versus time for different wavelengths, inducing a diffusive, superdiffusive and accelerated regime.

In addition, we predict the existence of Mock-Gravity attractive forces in a random light field, whenever the light frequency is tuned to an absorption line such that the real part of the particle's electric polarizability is zero. These interactions are scale independent, holding for both near and far-field separation distances. Figure 2 shows a log-log plot of the interaction force for two silver nanoparticles illuminated with a isotropic fluctuating random field with wavelengths (a) 317nm, (b) 337nm, (c) 352nm and (d) 470nm. Red shadowed regions indicate repulsive interaction forces.

REFERENCES

[1] Marqués M.I.   Opt. Lett. 41, 796 (2016).

[2] Marqués M.I. Phys. Rev. A 93, 063815 (2016).

[3]López Pastor Vícotr J, Marqués M.I. Submitted.

[7] Luis-Hita J, Marqués M.I, Delgado-Buscalioni R., de Sousa N., Froufe-Pérez L.S, Scheffold F, Sáenz J.J.  arXiv:1802.05648, 15 Feb 2018.