F. Dalfovo

Theory of Bose-Einstein condensation in trapped gases

The phenomenon of Bose-Einstein condensation of dilute gases in traps is reviewed from a theoretical perspective. Mean-field theory provides a framework to understand the main features of the condensation and the role of interactions between particles. Various properties of these systems are discussed, including the density profiles and the energy of the ground-state configurations, the collective oscillations and the dynamics of the expansion, the condensate fraction and the thermodynamic functions. The thermodynamic limit exhibits a scaling behavior in the relevant length and energy scales. Despite the dilute nature of the gases, interactions profoundly modify the static as well as the dynamic properties of the system; the predictions of mean-field theory are in excellent agreement with available experimental results. Effects of superfluidity including the existence of quantized vortices and the reduction of the moment of inertia are discussed, as well as the consequences of coherence such as the Josephson effect and interference phenomena. The review also assesses the accuracy and limitations of the mean-field approach.

Structural and dynamical properties of superfluid helium: A density-functional approach.

We present a novel density functional for liquid 4He, properly accounting for the static response function and the phonon-roton dispersion in the uniform liquid. The functional is used to study both structural and dynamical properties of superfluid helium in various geometries. The equilibrium properties of the free surface, droplets and films at zero temperature are calculated. Our predictions agree closely to the results of ab initio Monte Carlo calculations, when available. The introduction of a phenomenological velocity dependent interaction, which accounts for backflow effects, is discussed. The spectrum of the elementary excitations of the free surface and films is studied.

Density of superfluid helium droplets

The classical integral cross sections of large superfluid 4 He N droplets and the number of atoms in the droplets (N = 10 3 − 10 4 ) have been measured in molecular beam scattering experiments. These measurements are found to be in good agreement with the cross sections predicted from density functional calculations of the radial density distributions with a 10–90% surface thickness of 5.7u By using a simple model for the density profile of the droplets a thickness of about 6–8u is extracted directly from the data.

Superfluid Hydrodynamic Model for the Enhanced Moments of Inertia of Molecules in Liquid 4 He

We present a superfluid hydrodynamic model for the increase in moment of inertia,

Atomic and molecular impurities in4He clusters

\Delta I

Dynamical Response of a Bose-Einstein Condensate to a Discontinuous Change in Internal State

, of molecules rotating in liquid

Order parameter at the boundary of a trapped Bose gas

^4

Spontaneous creation of Kibble–Zurek solitons in a Bose–Einstein condensate

He. The static inhomogeneous He density around each molecule (calculated using the Orsay-Paris liquid

Observation of Subdiffusion in a Disordered Interacting System

^4

Helium nanodroplets and trapped Bose–Einstein condensates as prototypes of finite quantum fluids

He density functional) is assumed to adiabatically follow the rotation of the molecule. We find that the