  Intense ultrafast laser excitation can produce transient states of condensed
matter that would otherwise be inaccessible. At high excitation level, the
interatomic forces can be altered resulting in an unusual lattice dynamics.
Here we report the study of coherent lattice dynamics in Bi made for various
excitation levels at helium temperature. We demonstrate that under certain
conditions the fully symmetric phonons of large amplitude exhibit anomalous
decay and phase rigidity, both of which possibly signaling the attainment of
transient supersolid state.
