Hierarchy of magnon mode entanglement in antiferromagnets

Magnon-magnon entanglement and its detection in a microwave cavity

“…Relevant for the present investigation, it was suggested in Ref. [11] that one may identify a hierarchy of magnon mode entanglement in antiferromagnetic materials. The motivation for studies of entanglement in magnetic materials can be traced to the development of modern synthetic routes that allow most combinations of elements to form a magnetic material with tailored properties.…”

“…Detailed analyses in section B of the appendix and also in Ref. [11] show that the entanglement parameter r k and therefore the entanglement entropies are only given by absolute value of the ratio Γ k ∝…”

“…Based on these considerations, a hierarchy of magnon mode entanglement in antiferromagnets of the kind discussed here, has been analyzed in detail [11]. Here, we make use of the fact that entanglement entropies of all energy eigenbasis states in the (a, b) modes can be written as…”

“…Indeed, finite entanglement entropies between a and b magnon modes in the case of H 1 = 0, indicate that the antiferromagnetic interaction creates bipartite continuousvariable entanglement between the two ferromagnets in a way that each energy eigenstate becomes an entangled two-magnon-mode coherent state (see section B of the appendix as well as Ref. [11]). Each of the energy eigenstates is a coherent superposition of joint excitations of ferromagnetic magnons in a and b modes.…”

“…Recently, studies of entanglement between different components of a hybrid magnonic system have been under focus, as a fundamental element in a quantum device design [3][4][5][6][7][8][9][10][11]. Relevant for the present investigation, it was suggested in Ref.…”