20.500.12556/RUL-159767 Tunable entangled photon-pair generation in a liquid crystal Liquid crystals, with their ability to self-assemble, strong response to an electric field and integrability into complex systems, are key materials in light-beam manipulation. The recently discovered ferroelectric nematic liquid crystals also have considerable second-order optical nonlinearity, making them a potential material for nonlinear optics. Their use as sources of quantum light could considerably extend the boundaries of photonic quantum technologies. However, spontaneous parametric down-conversion, the basic source of entangled photons, heralded single photons and squeezed light, has so far not been observed in liquid crystals—or in any liquids or organic materials. Here we implement spontaneous parametric down-conversion in a ferroelectric nematic liquid crystal and demonstrate electric-field tunable broadband generation of entangled photons, with an efficiency comparable to that of the best nonlinear crystals. The emission rate and polarization state of photon pairs is markedly varied by applying a few volts or twisting the molecular orientation along the sample. A liquid-crystal source enables a special type of quasi-phase matching, which is based on the molecular twist structure and is therefore reconfigurable for the desired spectral and polarization properties of photon pairs. Such sources promise to outperform standard nonlinear optical materials in terms of functionality, brightness and the tunability of the generated quantum state. The concepts developed here can be extended to complex topological structures, macroscopic devices and multi-pixel tunable quantum light sources. liquid crystals nonlinear optics quantum information quantum oprics tekoči kristali nelinearna optika kvantna informacija kvantna optika true false true Angleški jezik Slovenski jezik Članek v reviji 2024-07-24 08:14:41 2024-07-24 08:14:42 2024-07-25 03:52:45 0000-00-00 00:00:00 2024 0 0 Str. 294-299 iss. 8020 Vol. 631 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2024-06-12 538.9:535 0028-0836 10.1038/s41586-024-07543-5 199216387 s41586-024-07543-5_(1).pdf s41586-024-07543-5_(1).pdf 1 CEB6D0045E4C9B7ED09E1FC3B8FBB357 4e8b83529a57874b51e6e43113cee57648c359e430cca4343cb8bc13767f05fa 51e2f0d4-498d-11ef-8f74-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=187965 https://www.nature.com/articles/s41586-024-07543-5 0 6da0523e-498d-11ef-8f74-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=187966 Fakulteta za matematiko in fiziko 0 0 0