  We propose to store non-classical states of light into the macroscopic
collective nuclear spin ($10^{18}$ atoms) of a $^3$He vapor, using
metastability exchange collisions. These collisions, commonly used to transfer
orientation from the metastable state $2^{3}S\_1$ to the ground state state of
$^3$He, can also transfer quantum correlations. This gives a possible
experimental scheme to map a squeezed vacuum field state onto a nuclear spin
state with very long storage times (hours).
