Signature of Magnon-Raman Phonon-Polariton Condensation in a Cavity via Transverse Pumping

arXiv:2607.26601v1 Announce Type: new Abstract: Polaritons---hybrid light-matter quasiparticles---provide a versatile platform for dynamically controlling a wide range of condensed matter systems. While conventional polaritonic platforms rely on direct dipole coupling, controlling dipole-forbidden or Raman-active lattice and spin excitations remains challenging due to optical selection rules and the limitations of THz cavities. Here, we propose a theoretical platform for realizing a continuous-wave magnon--Raman phonon--polariton condensate. By embedding a magnetic medium hosting strongly coupled magnon and Raman-active phonon (MRP) modes inside an optical microcavity under continuous-wave transverse laser pumping, we derive the stationary-state phase diagram and demonstrate the emerging signature of distinct MRP condensation phases under critical conditions. Furthermore, since the bare magnon frequency is tunable via an external magnetic field, we show that the transverse pump frequency and the external magnetic field-dependent magnon simultaneously as highly flexible control parameters for exploring and controlling macroscopic quantum phenomena at the interface of cavity quantum optics, lattice dynamics, and quantum magnetism.