  Two dimensional layered van der Waals (vdW) magnets have demonstrated their
potential to study both fundamental and applied physics due to their remarkable
electronic properties. However, the connection of vdW magnets to spintronics as
well as quantum information science is not clear. In particular, it remains
elusive whether there are novel magnetic phenomena only belonging to vdW
magnets, but absent in the widely studied crystalline magnets. Here we consider
the quantum correlations of magnons in a layered vdW magnet and identify an
entanglement channel of magnons across the magnetic layers, which can be
effectively tuned and even deterministically switched on and off by both
magnetic and electric means. This is a unique feature of vdW magnets in which
the underlying physics is well understood in terms of the competing roles of
exchange and anisotropy fields that contribute to the magnon excitation.
Furthermore, we show that such a tunable entanglement channel can mediate the
electrically controllable entanglement of two distant qubits, which also
provides a protocol to indirectly measure the entanglement of magnons. Our
findings provide a novel avenue to electrically manipulate the qubits and
further open up new opportunities to utilize vdW magnets for quantum
information science.
