中国科学技术大学李林、曾长淦和北京量子信息科学研究院解弘毅团队，合作报道了石墨烯与LaAlO3/SrTiO3超导体之间的约瑟夫森–库仑阻力效应。2023年1月12日出版的《自然—物理学》发表了这项成果。
研究团队展示了约瑟夫森结阵列的有源正常导体和无源超导体之间的库仑拖拽效应，其中无源电流与有源电流是同一阶的。拖曳力源于无源层中超导相与有源层中正常电子之间显著增强的动态量子涨落的相互作用。研究组在单层石墨烯和LaAlO3/SrTiO3异质界面组成的器件中证明了这一效应。
在最佳栅极电压下，估计的无源/有源比可达0.3左右，温度依赖性遵循超导坑之间的典型约瑟夫森能量。从工程角度来看，他们的设备可以作为电流或电压变压器，而拖动机制为同步约瑟夫森结阵列的太赫兹散热器奠定了基础。
据了解，库仑阻力是指一个电子电路中的电荷电流仅通过库仑相互作用在邻近电路中引起响应电流的现象。对于传统的电子之间的相互作用，被动层中的感应阻力电流比有源电流弱几个数量级，这是由于它们之间存在强烈的介电屏蔽效应。
附：英文原文
Title: Josephson–Coulomb drag effect between graphene and a LaAlO3/SrTiO3 superconductor
Author: Tao, Ran, Li, Lin, Xie, Hong-Yi, Fan, Xiaodong, Guo, Linhai, Zhu, Lijun, Yan, Yuedong, Zhang, Zhenyu, Zeng, Changgan
Issue&Volume: 2023-01-12
Abstract: Coulomb drag refers to the phenomenon in which a charge current in one electronic circuit induces a responsive current in a neighbouring circuit solely through Coulomb interactions. For conventional interactions between electrons, the induced drag current in the passive layer is orders of magnitude weaker than the active current due to the strong dielectric screening effect between them. Here we show a Coulomb drag effect between an active normal conductor and a passive superconductor of Josephson junction arrays, where the passive current is of the same order as the active one. The drag force originates from the interactions between the substantially enhanced dynamical quantum fluctuations of the superconducting phases in the passive layer and normal electrons in the active layer. We demonstrate this effect in devices composed of monolayer graphene and LaAlO3/SrTiO3 heterointerface. The estimated passive-to-active ratio can reach about 0.3 at the optimal gate voltage and the temperature dependence follows that of the typical Josephson energy between superconducting puddles. From an engineering perspective, our device may work as a current or voltage transformer, and the drag mechanism lays the foundation for synchronizing Josephson-junction-array-based terahertz radiators.
DOI: 10.1038/s41567-022-01902-7
Source: https://www.nature.com/articles/s41567-022-01902-7