物理学家发现超导性的"幽灵"——对密度波直接证据

伊利诺伊大学厄巴纳-香槟分校的物理学家在铀二碲化物中首次发现了对密度波（PDWs）的直接证据1。这一发现表明，库珀对可以组织成波纹状图案，而这些图案即使在材料超导性消失后仍能保持存在1。使用向量磁场扫描隧道显微镜进行的实验证实了这一不寻常的超导行为1。

该研究成果已发表在《美国国家科学院院刊》2026年第123卷第29期1。铀二碲化物的超导临界温度为2开尔文以下1，被认为属于三重态对超导体1。研究团队包括Eduardo Fradkin和Vidya Madhavan等科学家1。

Eduardo Fradkin教授用生动的比喻描述了这一发现的意义，他表示："对密度波是超导性的Cheshire Cat的微笑，是相消失后留下的残迹"1。这意味着电子对可能在材料进入超导状态前就已开始形成1。对密度波理论最初由Eduardo Fradkin等人在2007年提出1。该研究获得美国能源部基础能源科学办公室、材料科学与工程部的资助1。

Researchers at the University of Illinois Urbana-Champaign have identified direct evidence of pair density waves (PDWs) in uranium ditelluride, an unusual manifestation of superconducting behavior 1. Using vector magnetic field scanning tunneling microscopy, the team demonstrated that Cooper pairs—the electron pairs responsible for superconductivity—can organize themselves into ripple-like patterns that persist even after the material loses its superconducting properties 1. This discovery suggests that electron pairing may begin before the material enters its superconducting state, revealing a hidden order that survives the disappearance of superconductivity itself.

The material exhibits superconductivity at temperatures below 2 Kelvin and is understood to be a triplet-pairing superconductor 1. According to Eduardo Fradkin, a key researcher involved in the study, pair density waves represent "the Cheshire Cat's smile of superconductivity—the grin that remains after the cat has disappeared" 1. The theoretical framework for pair density waves was developed by Fradkin and colleagues in 2007, and this work provides the first direct experimental confirmation of their existence 1. The findings have been published in the Proceedings of the National Academy of Sciences, Volume 123, Issue 29, in 2026, and were supported by the U.S. Department of Energy's Office of Basic Energy Sciences and the Division of Materials Science and Engineering 1.