Hongqi Xu

Peking University

Physics of Semiconductor Josephson Junctions with Strong Correlation and under Microwave Irradiation by Professor Hongqi Xu

Semiconductor-superconductor hybrid quantum devices have in recent years been extensively explored for revealing new, exotic physics in condensed matter and for potential applications in superconducting electronics and topological quantum computing technologies. In this talk, I will present our recent results obtained in the studies of the physics of semiconductor Josephson junction (JJ) devices [1-3]. The devices we studied were made from strong spin-orbit coupled semiconductor nanostructures, grown by molecular beam epitaxy (MBE) [4-6], and s-wave superconductor Al, which is either epitaxially grown in situ on semiconductor nanostructures in MBE [7] or deposited on ex situ using advanced nanofabrication techniques [1,6]. The devices were studied by quantum transport measurements in dilution refrigerators equipped with a uniaxial or a three-dimensional vector magnet and an attenuated high-frequency transmission line setup for microwave irradiation. After a brief overview of the quantum computing technologies we are pushing in Beijing, I will first present the physics of semiconductor quantum-dot JJ devices we have studied in recent years, including, e.g., complex quantum phase transition and anomalous negative magnetoresistance [8,9]. Then I will present and discuss our latest works on the studies of Al-InAs nanowire-Al JJs [2] and Al-InSb nanosheet-Al JJs [3] under microwave irradiation.

References

[1] S. Yan et al., Nano Lett. 23, 6497 (2023).

[2] H. Su et al., Phys. Rev. Lett., 133, 087001 (2024).

[3] X. Wu et al., arXiv:2403.07370.

[4] D. Pan et al., Nano Lett. 14, 1214 (2014).

[5] D. Pan et al., Nano Lett. 16, 834 (2016).

[6] N. Kang et al., Nano Lett. 19, 561 (2019).

[7] D. Pan et al., Chin. Phys. Lett. 39, 058101 (2022).

[8] M. Lee et al., Phys. Rev. Lett. 129, 207701 (2022).

[9] M. Deng et al., Sci. China-Phys., Mech. & Astron. 67, 280362 (2024)

Curriculum Vitae of Hongqi Xu

Hongqi Xu is Chair Professor at Peking University and Chief Scientist at Beijing Academy of Quantum Information Sciences. He received his Ph.D. degree in condensed matter physics in 1991 from Lund University, Sweden. From 1991 to 1993, he was employed as Postdoctoral Fellow at Linkoping University, Sweden. In 1993, he returned to Lund University, where he was employed as Research Associate in 1993-1995 and was appointed Assistant Professor in 1995-2001, Associate Professor in 2001-2003, and Full Professor in 2003-2014. He has been appointed Chair Professor at Peking University from 2010 and Director of Beijing Key Laboratory of Quantum Devices at Peking University from 2017. From 2021, he has also been appointed Chief Scientist and Executive Director for the Division of Quantum Computing at Beijing Academy of Quantum Information Sciences. He is a Fellow of the American Physical Society and a Fellow International of the Japan Society of Applied Physics.

His current research interests include experimental and theoretical studies of electron transport in quantum structures, topological states of matter, strong correlated systems, semiconductor spin physics and spin qubits, as well as semiconductor-superconductor hybrids towards topological quantum devices and quantum computing technologies.