腾讯会议：678-832-199

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报告摘要：

Noise spectroscopy provides a uniquely sensitive probe of effective charge and microscopic dynamics. To extend noise measurements to the atomic scale, we integrate shot noise detection with a scanning tunneling microscope, developing noise-STM.

In the first part of this talk, I will present how noise-STM can be used to probe Cooper pairing in superconductors, including conventional Pb and the high-Tc cuprate Bi₂Sr₂CaCu₂O_8+δ. By directly measuring the effective charge, we obtain evidence that the pseudogap energy is equal to the pairing energy. This results rule out the scenario in which the pseudogap arises solely from local competing orders, and instead indicates a direct connection between the pseudogap energy scale and Cooper pair formation.

In the second part, I will show recent results on the dynamics of single dopants in the semiconductor InAs at the atomic scale. Using noise-STM, we detect MHz-scale switching of electronic states, corresponding to intrinsic switching rates on the nanosecond timescale. These results demonstrate the capability of noise-STM as a local probe of fast electronic dynamics beyond conventional spectroscopy.

报告人简介：

Dr. Jiasen Niu received his PhD from Peking University in 2020. He then began his postdoctoral research at Leiden University under the supervision of Milan Allan. In 2024, he continued his postdoctoral work with Prof. Allan at Ludwig Maximilian University of Munich and he also became the leader of the Leiden branch of the Allan group.

Dr. Niu’s research focuses on investigating electron correlations and microscopic dynamics in high-temperature superconductors using shot noise based techniques. He is particularly interested in developing and applying unconventional noise spectroscopy methods to uncover quantum phenomena that are inaccessible to conventional measurements.

邀 请 人：沈 洁 特聘研究员

联 系 人：王慧颖 why@iphy.ac.cn