Year: 2026
Type: preprint
Abstract: The quantum Hopfield model is widely used to describe ultrastrong light--matter coupling between cavity photons and collective bosonic excitations in solids, where the diamagnetic interaction is conventionally assumed to be a constant. We experimentally demonstrate that the diamagnetic response of Landau polaritons is reduced under strong terahertz field excitation. We show that this behavior originates from field-driven redistribution of electrons into the nonparabolic regime of the conduction band of GaAs, which reduces the plasma frequency and consequently the diamagnetic interaction strength. A microscopic hot-electron model reproduces the observed nonlinear response. Motivated by this microscopic picture, we propose a nonlinear extension of the Hopfield model with a Kerr-like interaction. Our results establish a route toward nonlinear cavity quantum electrodynamics and driven ultrastrong light--matter coupling beyond the conventional linear Hopfield description, which is capable of creating uniquely quantum optical effects such as squeezed light generation.
Source: arXiv (Cornell University)
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1000240696, Development of ultrafast spin fluctuation spectroscopy system under magnetic field for the realization of field-controlled picosecond random telegraph noise, Thermal-equilibrium quantum squeezing by superradiant phase transition: For its detection, Development of cavity structures that enhance the magnetic-field vacuum fluctuation for realizing the superradiant phase transition, オンチップテラヘルツ光共振器を介した電子の量子ハイブリッド遠隔結合, G7621780109, G8156115730, 共振器-量子物質結合系の観測に向けたテラヘルツ電場ゆらぎ顕微鏡の開発
OpenAlex ID: W7204137490