Curator's Take
This article shows how a cavity‑magnon‑qubit platform can be leveraged to generate a two‑mode magnonic Schrödinger cat state, extending recent demonstrations of single‑mode magnon cats into the non‑Gaussian entangled regime. By exploiting bright and dark hybridized magnon modes together with a conditional‑displacement interaction driven by a superconducting qubit, the proposal yields strong nonclassical correlations that survive realistic dissipation rates, offering a viable route to macroscopic quantum resources for sensing and transduction. If experimentally realized, such states would provide a new testbed for studying decoherence of massive bosonic modes and could enrich hybrid quantum hardware architectures beyond purely photonic or phononic approaches.
— Mark Eatherly
Summary
The cavity-magnon-qubit system has recently been demonstrated as a new platform for preparing macroscopic quantum states in magnonic systems. Here, we propose to prepare a two-mode magnonic cat state, which is also a non-Gaussian entangled state, based on this practical system involving two yttrium-iron-garnet (YIG) spheres and a superconducting qubit coupled to a common microwave cavity. By adiabatically eliminating the cavity and resonantly driving the qubit, an effective magnon-qubit conditional-displacement interaction is achieved. Further working in the magnon-magnon strong-coupling regime and considering two identical magnon frequencies and coupling strengths to the cavity, two hybridized magnon modes are formed, of which the bright mode is prepared in a cat state after a projective measurement on the qubit, while the dark mode remains in its initial vacuum state. Such a state corresponds to a two-mode cat state of two original magnon modes, which share strong non-Gaussian entanglement. We also discuss practical dissipation and dephasing effects on the cat state. The results indicate that strong nonclassicality and non-Gaussian entanglement are present in the two-mode cat state using fully feasible parameters.