Starting from the Wigner-Moyal equation coupled to Poissons equation, a simplified set of equations describing nonlinear Landau damping of Langmuir waves is derived. This system is studied numerically, with a particular focus on the transition from t
he classical to the quantum regime. In the quantum regime several new features are found. This includes a quantum modified bounce frequency, and the discovery that bounce-like amplitude oscillations can take place even in the absence of trapped particles. The implications of our results are discussed.
A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in nonlinear Kerr me
dia and an extended phase space evolution equation is derived along with invariant quantities. We further consider modulation instability as well as the extension to partially coherent fields.
For quantum effects to be significant in plasmas it is often assumed that the temperature over density ratio must be small. In this paper we challenge this assumption by considering the contribution to the dynamics from the electron spin properties.
As a starting point we consider a multicomponent plasma model, where electrons with spin up and spin down are regarded as different fluids. By studying the propagation of Alfv{e}n wave solitons we demonstrate that quantum effects can survive in a relatively high-temperature plasma. The consequences of our results are discussed.
