  Strange metals exhibit universal linear-in-temperature resistivity described
by a Planckian scattering rate, the origin of which remains elusive. By
employing a novel approach inspired by quantum optics, we arrive at the
coherent state representation of lattice vibrations: quantum acoustics.
Utilizing this nonperturbative framework, we demonstrate that lattice
vibrations could serve as active drivers in the Planckian resistivity
phenomenon, challenging prevailing theories. By treating charge carriers as
quantum wave packets negotiating the dynamic acoustic field, we find that a
competition ensues between localization and delocalization giving rise to the
previously conjectured universal quantum bound of diffusion, $\hbar/m^{*}$,
independent of temperature or any other material parameters. This leads to the
enigmatic $T$-linear resistivity over hundreds of degrees, except at very low
temperatures. Quantum diffusion also explains why strange metals have much
higher electrical resistivity than typical metals. Our work elucidates the
critical role of phonons in Planckian resistivity from a new perspective and
reconsiders their significance in the transport properties of strange metals.
