OPTOMECHANICAL COLLECTIVE EFFECTS USING COLD ATOMS IN FREE SPACE: COLLECTIVE ATOMIC RECOIL LASING & OPTICAL BINDING
Tesi di Dottorato
Data di Pubblicazione:
2020
Citazione:
OPTOMECHANICAL COLLECTIVE EFFECTS USING COLD ATOMS IN FREE SPACE: COLLECTIVE ATOMIC RECOIL LASING & OPTICAL BINDING / A. Tarramera Gisbert ; supervisore: N. Piovella ; direttore scuola dottorato: M.G. Paris. Dipartimento di Fisica Aldo Pontremoli, 2020 Dec 11. 32. ciclo, Anno Accademico 2019. [10.13130/tarramera-gisbert-angel_phd2020-12-11].
Abstract:
This theoretical doctoral thesis investigates the collective effects that emerge in
cold atomic systems caused by light-scattering in free space. Two specific cases are
investigated: the collective atomic recoil laser (CARL) effect in a cold gas, without
optical cavity, and a novel cooperative cooling effect via optical binding (OB) with
cold atoms.
As a main objective, this theoretical project investigates the spatial grating
structures and the backward radiation that appears in a cold atomic cloud when
it is irradiated by a single far-detuned laser beam, also known as CARL effect.
While this effect has traditionally been described using a ring cavity, the study is
performed here in free space, in the absence of such a cavity. Both 2D and 3D clouds
show a transition from single-atom isotropic scattering to collective directional
scattering. The effect is shown by the derivation and numerical solution of a set of
multi-particle motion equations coupled by a self-consistent optical field, which is
inspected with both a scalar model and a vectorial model. New original approaches
are used to address the numerical study of the dynamics of the atomic system, such
as molecular dynamics (MD) algorithms.
A second system emerged, from the attempt to understand the main objective,
where a few atoms rearrange themselves into crystalline atomic structures, with a
periodicity between particles close to the optical wavelength. The atomic system
is initially confined into a 2D plane (or 1D string) using two (or four) counter-propagating
laser beams. Due to the multiple scattering experienced by all the
particles in the system, a dipole-dipole force arises among them, generating a non-trivial
dynamical trapping potential landscape that compels the atoms, to self-organize
at distances multiple of the light wavelength. When atoms are rearranged
into an atomic crystal, the force acting on each particle depends on the position of
the others, thus allowing to study the stability of such optically bound structures.
In addition, it turns out that a non-conservative force is generated from the
dipole-dipole interaction, allowing the system to be cooled by controlling the value
of certain parameters. This new phenomenon arises as a direct consequence of the
use of cold atoms instead of dielectric nanoparticles in an OB system. Therefore,
besides the atomic external motion, internal degrees of freedom (DOF) of the atoms
are considered by treating each atom as a dipole. This latter aspect is investigated
using the coupled dipole equations. When multiple atoms are set in line, the cooling
mechanism is collectively enhanced, generating a novel cooperative cooling effect.
Tipologia IRIS:
Tesi di dottorato
Keywords:
cold atoms; collective effects; cooperative effects; cooling mechanism; CARL; Collective Atomic Recoil Lasing; Optical Binding;
Elenco autori:
A. TARRAMERA GISBERT
Link alla scheda completa: