Collective oscillations in ultracold atomic gas

Abstract

Using both fluid and kinetic descriptions, where repulsive forces between near by atoms are included, we discuss the basic oscillations and waves of a cloud of ultra-cold atoms confined in a magneto-optical trap. The existence of a hybrid mode, with properties similar to both plasma and acoustic waves is described in detail. Tonks-Dattner resonances for confined hybrid modes in a spherical cloud are discussed and the prediction of a nonlinear coupling between the dipole resonanc and the hybrid modes is considered. Landau damping processes and quasi-linear diffusion in velocity space are also discussed.

Polytropic equilibrium and normal modes in cold atomic traps

“…Under these circumstances, the atoms experience a mediated long-range interaction potential similar to a Coulomb potential (∼ 1/r) [11] and the system can therefore be regarded as a one-component trapped plasma. In a series of previous works, we have put in evidence the important consequences of such plasma description of a cold atomic traps [12], whereas the formal analogy and the application of plasma physics techniques reveal to be important in the description of driven mechanical instabilities [14] or even more exciting instability phenomena, like photon bubbles [15], phonon lasing [16] or even the appearance of a roton minimum in the classical regime [17].…”

“…Here, F c is the collective force and Q = (σ R − σ L )σ L I 0 /c represents the square of the effective electric charge of the atoms [11,12], with c being the speed of light, I 0 the total intensity of the six laser beams. σ R and σ L represent the emission and absorption cross sections respectively [2].…”

“…Here, µ B represents the Bohr magneton, κ = κ(δ, I 0 /I s ) is the spring constant, α = α(δ, I 0 /I s ) is the friction coefficient, δ is the laser detuning, I s is the atomic saturation intensity and ∇B = |∇B| represents the magnetic field gradient [12]. The harmonic trapping potential 4 is valid for a MOT of maximum radius R max = |δ|/(γ M ∇B), where γ M = g J µ B /h and g J is the Land factor.…”

“…A simple description of a cold gas in the presence of long-range interactions can be done using a set of hydrodynamic equations considered in our previous paper [12] ∂n ∂t + ∇ · (nv) = 0…”

Magnetization of Rydberg plasmas by electromagnetic waves

“…Recently, there has been a great deal of interest [3][4][5][6][7][8][9][10][11] in investigating various aspects of the UCPs, including a stable electron plasma wave [3][4][5], an instability [8] arising from the coupling between the electron drift wave and a harmonic of the electron gyrofrequency, expansion in a magnetic field [9] and a new electromagnetic mode [11].…”