On the 1-D Plasma-Like Model for Studying Nonlinear Oscillations and Wave Propagation in Ultracold Gases

We investigated hybrid modes and traveling wave propagation in an ultracold atomic gas. Using both fluid and kinetic plasma description models, we treat the nonlinear oscillation modes of a cloud of ultracold atoms confined in a magneto-optical trap (MOT). The effect of repulsive forces between nearby atoms is discussed, through the key parameter <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z_{\mathrm { eff }}q_{\mathrm { eff}}$ </tex-math></inline-formula> which ranges from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-5}e$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-3}e$ </tex-math></inline-formula>. The gas is treated as an effective plasma-like single species. We focused on wave propagation dynamics, considering only thermal pressure and effective Coulomb interaction effects. A small amplitude wave analysis revealed the existence of nonlinear plasma-like oscillations and cnoidal structure waves governed by the effective charge number (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z_{\mathrm { eff}}$ </tex-math></inline-formula>).