Special CPM Seminar

Quantum Phase Transition, Unidirectional Superconductivity and Missing Shapiro Steps in Semiconductor Josephson Junctions

Hongqi Xu

Beijing Key Laboratory of Quantum Devices and School of Electronics
Peking University

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 superconductor electronics and quantum computing technologies. In this talk, I will present our recent results obtained in experimental 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 cable setup for microwave irradiation. After a brief overview of the physics of semiconductor JJ devices we have studied in recent years, including, e.g., complex quantum phase transition and anomalous negative magnetoresistance in semiconductor quantum-dot JJs [8,9], I will focus on our latest results obtained in 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., in print (2024); arXiv:2402.02137.
[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. in press (2024)