Coherent resonant transport of magnons through a ferromagnetic chain: A possible way to establish quantum communication between nanomagnets embedded in microwave cavities

In hybrid microwave structures based on magnonics (so-called magnon cavities), the energy of the electromagnetic field can be transduced into the energy of magnetostatic spin excitations of a nanomagnet (Kittel magnon). This paper proposes a mechanism for transfer of coherent long-range spin excitation between nanomagnets, showing how Kittel magnons can be used for communication between magnon cavities. Analytical expressions for the magnon transport rate are obtained, and key parameters controlling off-resonant and resonant magnon tunneling regimes are indicated. Physical conditions are determined under which peak values of the rate characterizing the resonant transmission of the Kittel magnon arise either at a fixed tunneling energy with an arbitrary number of units in the ferromagnetic chain or at a fixed number of chain units with a varying tunneling energy. The features of resonant tunneling of the Kittel magnon formed in a magnon cavity at frequencies of about 10 GHz are analyzed. It is also shown that due to the strong photon-magnon coupling in the magnon cavity, at a certain magnetic field, the tunneling flow of magnons can reach an additional peak value, which reflects the process of resonant photon-to-magnon conversion.