Electrodynamics of photonic temporal interfaces - Nature

IntroductionPolarization is a fundamental degree of freedom of light and plays a central role in a wide range of optical systems, from classical and quantum communications1,2,3 to sensing4, imaging5,6,7, and metrology8. The ability to generate, manipulate, and analyze arbitrary polarization states enables advanced functionalities such as polarization-division multiplexing, polarization-resolved coherent detection, ellipsometry, and polarimetric imaging. As photonic systems continue to scale in complexity and performance, precise and reconfigurable control over polarization has become increasingly important. An integrated platform that can both generate and analyze arbitrary polarization states enables a self-contained polarimetric system, eliminating the need for external optics and simplifying system-level integration. Such capability is particularly attractive for applications requiring real-time polarization tracking, adaptive compensation, or compact instrumentation, including coherent transceivers, polarization-sensitive sensors, and on-chip quantum photonic circuits.