Interactions of classical and quantum fields

Jacques Chauveheid

Yi Qian, Jing‐Bo Xu

We investigate a two-level atom interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence and find that a stationary quantum discord can arise in the interaction of the atom and cavity field as the time turns to infinity. We also find that the stationary quantum discord can be increased by applying a classical driving field. Furthermore, we explore the quantum discord dynamics of two identical non-interacting two-level atoms independently interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence. Results show that the quantum discord between two atoms is more robust than entanglement under phase decoherence and the classical driving field can help to improve the amount of quantum discord of the two atoms.

Ariel Arza, Sankha Subhra Chakrabarty, Seishi Enomoto +2 more

Quantum fields with large degeneracy are often approximated as classical fields. Here, we show how the quantum and classical evolution of a highly degenerate quantum field with repulsive contact self-interactions differ from each other. Initially, the field is taken to be homogeneous except for a small plane-wave perturbation in only one mode. In quantum field theory, modes satisfying both momentum and energy conservation of the quasiparticles, grow exponentially with time. However, in the classical field approximation, the system is stable. We calculate the time scale after which the classical field description becomes invalid.

Jan Dereziński, Christian Gérard

X. Xia, R. Silbey

A classical field theory is constructed to describe the interacting classical particles in one-dimensional (1D) channels. We show the intrinsic connection between the classical field theory and the corresponding quantum theory, i.e., Tomonaga-Luttinger liquid theory, which describes the interacting fermions in 1D. As applications, we calculate the particle density function along the tube axis and the particle current through the channels by explicitly including the particle-particle and particle-wall interactions and we find quantum-classical correspondence in the conductance formula.