“Spectral Collapse via Two-phonon Interactions in Trapped Ions”

Spectral Collapse via Two-phonon Interactions in Trapped Ions.
S. Felicetti, J. S. Pedernales, I. L. Egusquiza, G. Romero, L. Lamata, D. Braak, and E. Solano. Phys. Rev. A 92, 033817 (2015).