纳米标准与检测重点实验室第183期学术报告

报 告 题 目：Sub-gap states in superconductor-semiconductor nanowire systems

报  告  人：Prof. Kasper Grove-Rasmussen, University of Copenhagen, Denmark

时      间：2018年3月12日（周一） 上午10: 30

地      点：南楼二层会议室

邀  请  人：裘晓辉 研究员

报告摘要：

This talk will primarily be on sub-gap states defined in bottom-gated hybrid superconductor-semiconductor nanowire devices. I will first give a general introduction to sub-gap states and outline why sub-gap states in nano-electronic systems are receiving increasing attention in the condensed matter physics community. Next, the so-called Yu-Shiba-Rusinov sub-gap states are explained via a simple model and measurements of these states in a single quantum dot (QD) coupled to one superconducting (S) lead are shown [1]. The behavior of these states is further investigated by expanding the system to a double quantum dot coupled to a single superconductor. An extended model shows that the characteristic normal state double dot honeycomb stability diagrams may appear different in the superconducting state, qualitatively consistent with measurements. I will also give hints about our ongoing work on YSR states in double dots with two superconducting leads.  Finally, I will outline how bent carbon nanotubes can be used to create non-colinear magnetic fields in quantum dots, a system potentially useful for entanglement detection of Cooper pairs [3]. 

[1] Jellinggaard, A., Grove-Rasmussen, K., Madsen, M.H., Nyg？rd, J., “Tuning Yu-Shiba-Rusinov states in a quantum dot”, Phys. Rev. B 94, 064520 (2016).

[2] Grove-Rasmussen, K., Steffensen, G., Jellinggaard, A., Madsen, M. H., ？itko, R., Paaske, J., and Nyg？rd, J., “Yu-Shiba-Rusinov screening in a double dot”, arXiv1711.0608.

[3] Hels, M., Braunecker, B., Grove-Rasmussen, K., Nyg？rd, J., ”Non-colinear Spin-orbit Magnetic Fields in a Carbon nanotube double quantum dot”, Phys. Rev. Lett. 117, 276802 (2016)

报告人简介：

Associate Prof. K. Grove-Rasmussen is an expert in experimental low-temperature quantum transport. He received his PhD in 2006 from University of Copenhagen and has during his career conducted research at Scuola Normale Superiore (Italy), Berkeley (US), Harvard (US) and NTT Basic Research Laboratories (Japan). His research has been focused on quantum dots, quantum wires, spin-orbit coupling and in particular exploring phenomena in hybrid superconductor-quantum dot/wires systems. The experimental platform for these studies have been and are based on carbon nanotubes and semiconductor nanowires.