Andreev reflection in quantum Hall systems: 2021 state of the union

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Collage of Andreev quantum Hall systems

A combination of superconductivity with quantum Hall effect allows perfectly nonlocal crossed Andreev reflection, which has made it a target of experimental search for more than a decade.

Due to progress in material physics and emergence of new hybrid platforms, this search has resulted in a series of experiments observing a combined effect of chiral edge states and superconductivity. At the same time, measurements of Andreev conductance in the quantum Hall regime demonstrate wildly different behaviors, sometimes in disagreement with existing theoretical predictions.

In this workshop we aim to bring together experts working in the field, review observations and their interpretation, and identify the possible ways forward.

To join the meeting, please register.

Program

Satellite talks

We invite the workshop participants to view the recordings of relevant talks below.

Mechanisms of Andreev reflection in quantum Hall graphene

By Antonio Manesco (TU Delft)

Authors: Antonio L. R. Manesco, Ian Matthias Flór, Chun-Xiao Liu, Anton R. Akhmerov
Preprint: arXiv:2103.06722

Integer quantum Hall states interacting with a superconducting electrode, are predicted to form Andreev edge states. This effect is expected to exhibit an oscillatory interference pattern in the longitudinal resistance, measured with respect to the grounded superconducting lead. In InSb-based two-dimensional electron gases we observe pronounced longitudinal resistance oscillations. However, we verify that the origin of such oscillation is not related to the superconductivity, but rather, transport through the bulk in the disordered quantum Hall regime. Understanding the origin and location in parameter states of these oscillations is important to clearly distinguish between trivial and superconducting effects in the quantum Hall regime.

Longitudinal resistance oscillations in InSbAs 2DEGs in a Quantum Hall regime

By Ivan Kulesh (QuTech, Delft University of Technology)

Authors: Ivan Kulesh, Mark van Blankenstein, Candice Thomas, Di Xiao, Geoffrey C. Gardner, Michael J. Manfra, Srijit Goswami
Preprint: arXiv:

Integer quantum Hall states interacting with a superconducting electrode, are predicted to form Andreev edge states. This effect is expected to exhibit an oscillatory interference pattern in the longitudinal resistance, measured with respect to the grounded superconducting lead. In InSb-based two-dimensional electron gases we observe pronounced longitudinal resistance oscillations. However, we verify that the origin of such oscillation is not related to the superconductivity, but rather, transport through the bulk in the disordered quantum Hall regime. Understanding the origin and location in parameter states of these oscillations is important to clearly distinguish between trivial and superconducting effects in the quantum Hall regime.

Mesoscopic conductance along the proximitized quantum Hall edge

by Vladislav D. Kurilovich (Department of Physics, Yale University)

Authors: Vladislav D. Kurilovich, Leonid Glazman
Preprint: arXiv:2201.00273

Induced Superconductivity in FQH Edges in Presence of Dissipation

by Noam Schiller (Weizmann Institute) and Barak A. Katzir (Technion)

Authors: Noam Schiller, Barak A. Katzir, Ady Stern, Erez Berg, Netanel Lindner, Yuval Oreg

Organizers

Anton Akhmerov, TU Delft
Valla Fatemi, Yale University & Cornell University
Christian Schoenenberger, University of Basel

If you have any questions, you may reach us via arqh2021@virtualscienceforum.org