Interaction of Matter and Electromagnetic Fields
Both semiconductor optics and transport are concerned with the intimate relationship between electromagnetic fields and matter. Charged particles and the resulting currents give rise to electromagnetic fields via the Maxwell equations . In turn, these fields lead to an interaction between the particles. For a closed system that is isolated from the outside world, these interactions can be completely incorporated into the equations of motion of charged particles — in classical mechanics simply via Newton’s law and the Lorentz force. On a quantum mechanical level, the coupling of matter and electromagnetic fields results again in an interacting many-particle system, which is described by the interaction Hamiltonian of fields and matter. In solid-state physics, the interaction is usually decomposed into a longitudinal, i.e. static, Coulomb interaction and a transverse, i.e. dynamic, part mediated by transverse photons. The range of these interactions extends from atomic scales up to the macroscopic dimensions of the system. Owing to the charge neutrality of the system as a whole, however, macroscopic fields usually do not exist in a closed system. Under the action of external sources, however, such macroscopic fields are generated, which carry a wealth of information about the interacting many-particle system.
KeywordsElectromagnetic Field Coherent State Vector Potential Dielectric Function Photon Number
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