We review a non-relativistic current algebra symmetry approach to constructing the Bogolubov generating functional of many-particle distribution functions and apply it to description of invariantly reduced Hamiltonian systems of the Boltzmann type kinetic equations, related to naturally imposed constraints on many-particle correlation functions. As an interesting example of deriving Vlasov type kinetic equations, we considered a quantum-mechanical model of spinless particles with delta-type interaction, having applications for describing so called Benney-type hydrodynamical praticle flows. We also review new results on a special class of dynamical systems of Boltzmann–Bogolubov and Boltzmann–Vlasov type on infinite dimensional functional manifolds modeling kinetic processes in many-particle media. Based on algebraic properties of the canonical quantum symmetry current algebra and its functional representations, we succeeded in dual analysis of the infinite Bogolubov hierarchy of many-particle distribution functions and their Hamiltonian structure. Moreover, we proposed a new approach to invariant reduction of the Bogolubov hierarchy on a suitably chosen correlation function constraint and deduction of the related modified Boltzmann–Bogolubov kinetic equations on a finite set of multi-particle distribution functions. There are also presented results of application of devised methods to describing kinetic properties of a many-particle system with an adsorbent surface, in particular, the corresponding kinetic equation for the occupation density distribution function is derived.
The article outlines key topics related to deriving kinetic equations and, in general, to the relationship between the evolution equations governing quantum many-particle systems. The main issues being considered are the mathematical origin of quantum kinetic equations, novel methods for deriving kinetic equations from hierarchies of evolution equations for quantum systems, specifically focusing on kinetics within the framework of the evolution of observables, and the generalization of the quantum kinetic equation specified by non-separable initial states.
Results are presented for the quench dynamics of a clean and interacting electron system, where the quench involves varying the strength of the attractive interaction along arbitrary quench trajectories. The initial state before the quench is assumed to be a normal electron gas, and the dynamics is studied in a regime where long-range order is absent, but nonequilibrium superconducting fluctuations need to be accounted for. A quantum kinetic equation using a two-particle irreducible formalism is derived. Conservation of energy, particle number, and momentum emerge naturally, with the conserved currents depending on both the electron Green's functions and the Green's functions for the superconducting fluctuations. The quantum kinetic equation is employed to derive a kinetic equation for the current, and the transient optical conductivity relevant to pump-probe spectroscopy is studied. The general structure of the kinetic equation for the current is also justified by a phenomenological approach that assumes model F in the Halperin-Hohenberg classification, corresponding to a nonconserved order parameter coupled to a conserved density. Linear response conductivity and the diffusion coefficients in thermal equilibrium are also derived, and connections with Aslamazov-Larkin fluctuation corrections are highlighted. Results are also presented for the time evolution of the local density of states. It is shown that Andreev scattering processes result in an enhanced density of states at low frequencies. For a quench trajectory corresponding to a sudden quench to the critical point, the density of states is shown to grow in a manner where the time after the quench plays the role of the inverse detuning from the critical point.