Fig. 6: Electron, phonon density of states in K₃C₆₀.

Schematic of superconducting electron (top) and phonon (bottom) density of states in K₃C₆₀. As discussed in detail, the phonon spectrum contains a significant gap, separating lattice inter-molecular modes of the K₃C₆₀ crystal from the on-ball molecular vibrational modes. In the optimal quasi-particle trapping scenario, strong driving pushes 2Δ into the phonon gap, e.g. above \({\Omega }_{\max }\). Note that while the on-ball vibrations can provide dissipation for the Cooper pairs, a narrow electronic band can suppress resonant electronic scatters: Above the electronic bandwidth, quasi-particle generation is kinematically constrained.