IRIS Institutional Research Information System - AIR Archivio Istituzionale della Ricerca

IRIS è il sistema di gestione integrata dei dati della ricerca (persone, progetti, pubblicazioni, attività) adottato dall'Università degli Studi di Milano.

AIR nasce in UNIMI nel 2006 con lo scopo di raccogliere, documentare e conservare le informazioni sulla produzione scientifica dell'Università degli Studi di Milano e costituisce di fatto l'Anagrafe della ricerca dell'Ateneo.

We have obtained new information on the elementary excitations in superfluid He-4 by studying local observables relative to roton wave-packets built from accurate variational representations of the excited states. The same technique has been applied also to study a pure 2-Dimensional system, where the spectrum, computed through a variational Monte Carlo simulation, still shows a modified phonon-maxon-roton dispersion relation. In the roton region, collective quantum effects are present, but when the average momentum of the wave-packet matches with the wave-vector of the roton minimum the interference effects between neighboring atoms disappear and the local density and momentum essentially coincide with those of a single particle excitation. A roton, as well as a single particle excitation, has a velocity vector field which is very similar to that of a smoke-ring scaled down to atomic size.

Roton wave-packets in 3-dimensional and 2-dimensional He-4 / D. E. Galli, L. Reatto. - In: JOURNAL OF LOW TEMPERATURE PHYSICS. - ISSN 0022-2291. - 110:1-2(1998), pp. 437-442.

Powered by IRIS-about IRIS-Utilizzo dei cookie

 Copyright © 2021