  A $\gamma$-ray-nuclear quantum interface is suggested as a new platform for
quantum information processing, motivated by remarkable progresses in
$\gamma$-ray quantum optics. The main advantages of a $\gamma$ photon over an
optical photon lie in its almost perfect detectability and much tighter,
potentially sub-angstrom, focusability. Nuclear ensembles hold important
advantages over atomic ensembles in a unique combination of high nuclear
density in bulk solids with narrow, lifetime-broadening M\"ossbauer transitions
even at room temperature. This may lead to the densest long-lived quantum
memories and the smallest size photon processors. Here we propose a technique
for $\gamma$ photon quantum memory through a Doppler frequency comb, produced
by a set of resonantly absorbing nuclear targets that move with different
velocities. It provides a reliable storage, an on-demand generation, and a time
sequencing of a single $\gamma$ photon. This scheme presents the first
$\gamma$-photon-nuclear-ensemble interface opening a new direction of research
in quantum information science.
