奥本大学《Physical Review Letters》论文：激光脉冲让量子晶体电畴对齐约1皮秒
奥本大学物理学家证明，短激光脉冲可让一种量子晶体内部的微小电区对齐，并暂时改变其电学行为。研究由奥本大学物理系 Wencan Jin 副教授与研究生 Mohamed Kandil 领衔，论文获《Physical Review Letters》编辑推荐，实验晶体由日本国立产业技术综合研究所科学家制备。
团队研究的是一种改性钛酸锶材料。材料中电子可移动，同时含有带正负电侧的微小区域，称极性纳米区。研究团队以灵敏的激光系统追踪晶体反复加热与冷却时对入射光的影响，监测电区取向。
结果显示，高温时这些区域取向看似随机，冷却时开始采用偏好取向，支持极性纳米区在对齐前已存在的观点。研究团队还证明激光脉冲可在较高温度下暂时组织这些区域，诱导对齐持续约1皮秒，即万亿分之一秒。Jin 表示，突破出现在2025年，当时 Kandil 观察到无序极性区在激光照射下对齐。
Auburn Paper in Physical Review Letters: Laser Pulses Align Electrical Regions in Quantum Crystal for About One Picosecond
Physicists at Auburn University have shown that brief pulses of laser light can align microscopic electrical regions inside a crystal, temporarily changing its electrical behaviour. The research was led by Wencan Jin, an associate professor in Auburn's Department of Physics, and graduate student Mohamed Kandil. Their paper received an Editors' Suggestion designation from Physical Review Letters, and crystals for the experiments were produced by scientists at Japan's National Institute of Advanced Industrial Science and Technology.
The team studied a modified form of strontium titanate. Electrons can move through the material, yet the crystal also contains tiny regions with positive and negative electrical sides, called polar nanoregions. The researchers developed a sensitive laser-based system to track subtle changes in the crystal as it was repeatedly heated and cooled, monitoring the orientation of its electrical regions.
At higher temperatures, the regions pointed in apparently random directions; as the crystal cooled, they began to adopt preferred orientations, supporting the view that the polar nanoregions are already present before they align. The team also demonstrated that laser pulses could temporarily organise the regions at higher temperatures, with the induced alignment lasting about one picosecond, one trillionth of a second. Jin said the breakthrough came in 2025, when Kandil observed the disordered polar regions becoming aligned under laser illumination.
来源：奥本大学
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图片来源：图中是钛酸锶（SrTiO3）的扫描透射电子显微图像，本研究对象为改性钛酸锶晶体。来源：Wikimedia Commons, File:Scanning transmission electron microscopy srtio3 compare adf abf.jpg, Magnunor, CC BY-SA 4.0。
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