学术报告（ 2025年12月22日16:00）：Epitaxial growth of hybrid semiconductor-superconductor nanowires with unconventional geometries for quantum devices

主持人：王猛 教授

报告摘要：

Due to its ultrapure environment, molecular beam epitaxy (MBE) has been the preferred synthesis method of nanostructures, including III-V nanowires. Based on MBE growth, the recent progress on hybrid superconducting materials has been enabling research on quantum devices. For example, the improvement of the interface between semiconductors and superconductors have facilitated experiments searching for the emerging quantum states that have been predicted to be formed in semiconductor nanowires coupled to conventional superconductors [1]. Motivated by these advances, designs and models have been proposed to explore those undiscovered quantum phenomena. Meanwhile, this comes with requirement of modifying the geometry of the materials and thus brings interesting challenges for nanowire growth.

Here, I will report on several novel examples of hybrid nanowires with geometries. First, InAs-EuS-Al ferromagnetic hybrid nanowires will be highlighted [2-4]. Second, by inducing phase transition between wurtzite and zinc blende, quantum dots are formed within Josephson junctions. These nanowires can be used to develop superconducting qubits. Third, the diameter of full-shell nanowires is modulated along nanowires, forming bottleneck structures that are expected to reveal phenomena beyond the conventional Little-Parks effect for superconducting cylinders. I will discuss the feasibility and the difficulties to realize the geometries in terms of growth and results of structural characterization by TEM will also be shown. The exploration of growing these hybrid nanowires does not only provide the possibilities to fabricate intriguing devices for quantum transport but also help deepen the understanding of growth mechanisms.

References

[1] E. Prada et al, Nat. Rev. Phys., 2, 575, (2020).

[2] Y. Liu et al, ACS Appl. Mater. Interfaces, 12, 8780, (2020).

[3] Y. Liu et al, Nano Lett., 20, 456, (2020).

[4] S. Vaitiekėnas et al, Nat. Phys., 17, 43, (2021).

报告人简介：Dr. Yu Liu is a quantum materials engineer working at Center for Quantum Devices, Niels Bohr Institute at University of Copenhagen. With a deep commitment to advancing quantum computing and communication technology, he has dedicated his efforts to unravelling the mechanisms and advancing technologies for solid-state material elaboration and modification. He got his PhD at University of Chinese Academy of Sciences in 2013. He is working at University of Copenhagen since 2017. His primary research area lies in MBE growth of III-V semiconductor – superconductor hybrid nanostructures. So far, he has published 70 high-quality papers, including those in prestigious journals such as Nature Physics and Physical Review Letters.