Time: 09:30 am (UTC/GMT+08:00, Beijing/Shanghai), Aug. 5 (Wedn.), 2020

Online Meeting Room (zoom.com):  Click here to join the meeting

Meeting ID: 997 1477 0993

Speaker: Ding Zhang (Tsinghua)

Abstract:

The quantum Hall bilayer is a unique platform for addressing exotic physics beyond quantum Hall effects [1]. At a total filling factor of one, the system behaves as a Bose-Einstein condensate of excitons and its interlayer coupling very much resembles that of a Josephson junction. In this talk, I will give an overview of these interesting phenomena and discuss our latest experiment in the strongly coupled regime. We observed that the exciton condensate can be confined in domains, suggesting novel behaviors not accounted for by the current theoretical understandings [2]. While the bulk physics has been intensively studied, the edge of a quantum Hall bilayer remained largely unexplored. The second part of this talk will be dealing with this issue. We recently managed to realize the quasi-particle tunneling across a quantum point contact in the bilayer [3]. Interestingly, we extracted a small fractional charge from the inter-edge tunneling by using the formula derived for quasi-particle tunneling in a single layer system. It suggests that the chiral edge interacts strongly with the bulk, which hosts gapless excitations.

[1] J. Eisenstein, Annu. Rev. Condens. Matter Phys. 5, 159 (2014)

[2] D. Zhang, W. Dietsche, and K. von Klitzing, Phys. Rev. Lett. 116, 186801 (2016), Editors’ Suggestion.

[3] D. Zhang, et al. Phys. Rev. Lett. 124, 246801 (2020)