Extensive efforts have been undertaken to combine superconductivity and the quantum Hall effect so that Cooper-pair transport between superconducting electrodes in Josephson junctions is mediated by quantized edge states. This interest is currently motivated mainly by the prospect of creating topologically protected quasiparticles but also extends into metrology and device applications. So far, it has proven challenging to achieve detectable supercurrents through quantum Hall conductors (1, 2).

In this talk I will show that domain walls in minimally twisted bilayer graphene support robust proximity superconductivity in quantizing fields (figure 1), allowing junctions with steady (non-oscillatory) critical currents over a several Tesla range approaching the upper critical field (3). The supercurrent is limited only by the quantum conductance of ballistic 1D channels residing inside the walls (4). These findings offer an interesting avenue for exploring both fundamental physics and device applications.
 

1. F. Amet et al., Science 352, 966 (2016)
2. H. Vignaud et al., arXiv :2305.01766 (2023)
3. J. Barrier et al., submitted (2023)
4. V.V. Enaldiev et al., arXiv :2307.14293 (2023)
 

Julien received his B.Sc. degree in Physics, Sorbonne Université - Université Pierre-et-Marie-Curie in 2016 and Ph.D. degree in Condensed Matter Physics, Manchester University, UK in 2022. He is currently Marie Skłodowska-Curie Actions Fellow in Quantum Nano-Optoelectronics of the ICFO - the Institute of Photonics Sciences.  His research interests include low temperature physics and mesoscale and nanoscale physics such as electronic transport in 2DEG, graphene and van der Waals heterostructures, quantum Hall effects, Josephson junctions, SQUIDs, applications in quantum communications and metrology.

Please contact phweb@ust.hk should you have questions about the talk.