DJ Resonances: Conditions for Anisotropy and Exchange-Driven Entangled State Switching in a Three Coupled Spin Particle Model*

Recent work has begun to uncover the utility of coupling higher-spin centers, such as molecular magnets and many-electron artificial molecules, as qubits. In this theoretical work, we investigate a representative model of a spin ½ particle coupled to two spin S particles to answer a vital question in conceptualization of such devices: can an electron prepare, manipulate, and interrogate the entanglement state of two-spin particles? By analyzing the model’s spin space, we report entangled state switching resonance conditions stemming from the interplay of exchange coupling (J) and magnetic anisotropy (D) and demonstrate the general resonance existence formula for any spin S for experimentally-relevant conditions. Using this general formula, we compare the entanglement switching mechanisms for the S_2,3 = ½ and S_2,3 = 1 models. We find that the inclusion of magnetic anisotropy in the S_2,3 = 1 model enables an additional control mechanism of a representative Bloch vector in several spin subspaces.