Spectrum of light in a quantum fluctuating periodic structure.
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.
Laboratoire Kastler Brossel, Ecole Normale Supérieure, CNRS and UPMC, Paris, France.
Mauro
M
Antezza
Yvan
Y
Castin