arXiv:0903.0765 · Physical Review Letters
Spectrum of Light in a Quantum Fluctuating Periodic Structure
Mauro Antezza, Yvan Castin
Abstract
We address the general problem of the excitation spectrum for light coupled to scatterers having quantum fluctuating positions around the sites of a periodic lattice. In addition to providing an imaginary part to the spectrum, we show that these quantum fluctuations affect the real part of the spectrum, in a way that we determine analytically. Our predictions may be observed with ultracold atoms in an optical lattice, on a J = 0 --> J;{'} = 1 narrow atomic transition. As a side result, we resolve a controversy for the occurrence of a spectral gap in a fcc lattice.