This research demonstrates the control of the magnetic state of the proximate quantum spin liquid α-RuCl₃ using a Fabry-Pérot cavity. By manipulating cavity properties like mode frequency, photon occupation, and light-matter coupling strength, various magnetic phases predicted by the extended Kitaev model can be stabilized. Notably, THz regime cavity vacuum fluctuations alone transition α-RuCl₃ from a zigzag antiferromagnetic to a ferromagnetic state. Further, low-photon-limit cavity pumping achieves the antiferromagnetic Kitaev quantum spin liquid state.

Emil Viñas Boström, Adithya Sriram, Martin Claassen, Angel Rubio