We present a detailed investigation of one of the cleanest examples where it is possible to detect the “analog” Dynamical Casimir Effect in a Bose–Einstein condensate: an ultracold atom gas in toroidal confinement. The analytical solution of the time dependent Gross–Pitaevskii equation allows to follow the time evolution of the phonon spectrum and shows that periodic oscillations of the ring radius do not induce modulations in the density profile but give rise to the mixing of clockwise and anticlockwise modes, leading to the creation of pairs of entangled phonons in a squeezed vacuum state, if the drive frequency equals twice the frequency of the phonon mode. The Dynamical Casimir Effect is predicted to occur in the weakly interacting regime, where the Gross–Pitaevskii equation provides a faithful description of the many body dynamics. In the strong coupling limit, when the ultracold gas behaves as hard core bosons, the effect disappears and no amplification occurs. The presence of symmetry-breaking perturbations and finite temperature effects are also considered, as well as the comparison with the classical phenomenon of parametric amplification.
Nous présentons une enquête détaillée sur l’un des exemples les plus clairs où il est possible de détecter l’effet Casimir Dynamique « analogue » dans un condensat de Bose–Einstein : un gaz d’atomes ultrafroids en confinement toroïdal. La solution analytique de l’équation de Gross–Pitaevskii dépendant du temps permet de suivre l’évolution temporelle du spectre des phonons et montre que des oscillations périodiques du rayon de l’anneau n’induisent pas de modulations dans le profil de densité mais donnent lieu au mélange des modes dans le sens horaire et antihoraire, conduisant à la création de paires de phonons intriqués dans un état de vide comprimé, si la fréquence de l’entraînement est égale à deux fois la fréquence du mode de phonon. L’effet Casimir Dynamique est prévu se produire dans le régime d’interaction faible, où l’équation de Gross–Pitaevskii fournit une description fidèle de la dynamique à plusieurs corps. Dans la limite du couplage fort, lorsque le gaz ultrafroid se comporte comme des bosons de cœur dur, l’effet disparaît et aucune amplification ne se produit. La présence de perturbations de rupture de symétrie et des effets de température finie sont également considérés, ainsi que la comparaison avec le phénomène classique d’amplification paramétrique.
Revised:
Accepted:
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Mots-clés : Effet Casimir, Condensats Bose Einstein, fluctuations du vide
Manuele Tettamanti 1; Alberto Parola 2
@article{CRPHYS_2024__25_S2_A7_0, author = {Manuele Tettamanti and Alberto Parola}, title = {The {Dynamical} {Casimir} {Effect} in quasi-one-dimensional {Bose} condensates: the breathing ring}, journal = {Comptes Rendus. Physique}, publisher = {Acad\'emie des sciences, Paris}, year = {2024}, doi = {10.5802/crphys.210}, language = {en}, note = {Online first}, }
TY - JOUR AU - Manuele Tettamanti AU - Alberto Parola TI - The Dynamical Casimir Effect in quasi-one-dimensional Bose condensates: the breathing ring JO - Comptes Rendus. Physique PY - 2024 PB - Académie des sciences, Paris N1 - Online first DO - 10.5802/crphys.210 LA - en ID - CRPHYS_2024__25_S2_A7_0 ER -
Manuele Tettamanti; Alberto Parola. The Dynamical Casimir Effect in quasi-one-dimensional Bose condensates: the breathing ring. Comptes Rendus. Physique, Online first (2024), pp. 1-19. doi : 10.5802/crphys.210.
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