Spatially Extended Spinning Quantum Systems

An open quantum system composed of identical particles spinning in a constant longitudinal magnetic field and excited by a transverse electromagnetic wave is considered as a model for a typical nanocircuit component. The electromagnetic wave is carried by a microstrip transmission line terminated on a box, wherein the particles are introduced at an upper energy level and wherefrom they are extracted at a lower one; the released energy is partly surrendered to the electromagnetic wave yielding reflection amplification, and partly dissipated in a thermal bath. The state of the particles is described in terms of the spin and of the momentum (or position) coordinates. The interaction between the electromagnetic field and the momentum variables is neglected. The LlNDBLAD equations for the system in either representation are derived.