  Exploiting the effect of nonreciprocal magnons in a system with no inversion
symmetry, we propose a concept of a quantum information diode, {\it i.e.}, a
device rectifying the amount of quantum information transmitted in the opposite
directions. We control the asymmetric left and right quantum information
currents through an applied external electric field and quantify it through the
left and right out-of-time-ordered correlation (OTOC). To enhance the
efficiency of the quantum information diode, we utilize a magnonic crystal. We
excite magnons of different frequencies and let them propagate in opposite
directions. Nonreciprocal magnons propagating in opposite directions have
different dispersion relations. Magnons propagating in one direction match
resonant conditions and scatter on gate magnons. Therefore, magnon flux in one
direction is damped in the magnonic crystal leading to an asymmetric transport
of quantum information in the quantum information diode. A quantum information
diode can be fabricated from an yttrium iron garnet (YIG) film. This is an
experimentally feasible concept and implies certain conditions: low temperature
and small deviation from the equilibrium to exclude effects of phonons and
magnon interactions. We show that rectification of the flaw of quantum
information can be controlled efficiently by an external electric field and
magnetoelectric effects.
