We discuss the response of a quantum system to a time-dependent perturbation with spectrum Φ(ω) This is characterised by a rate constant D describing the diffusion of occupation probability between levels. We calculate the transition rates by first-order perturbation theory, so that multiplying Φ(ω) by a constant λ changes the diffusion constant to λD. However, we discuss circumstances where this linearity does not extend to the function space of intensities, so that if intensities Φi(ω) yield diffusion constants Di, then the intensity ∑i Φi(ω) does not result in a diffusion constant ∑i Di. This "semilinear" response can occur in the absorption of radiation by small metal particles.
|Number of pages||7|
|State||Published - 1 Sep 2006|
ASJC Scopus subject areas
- Physics and Astronomy (all)