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Quantized conductance with nonzero shot noise as a signature of Andreev edge state

Sahu, MR and Paul, AK and Sutradhar, J and Watanabe, K and Taniguchi, T and Singh, V and Mukerjee, S and Banerjee, S and Das, A (2021) Quantized conductance with nonzero shot noise as a signature of Andreev edge state. In: Physical Review B, 104 (8).

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Official URL: https://doi.org/10.1103/PhysRevB.104.L081404


Electrical conductance measurements have a limited scope in identifying Andreev edge states (AESs), which form the basis for realizing various topological excitations in quantum Hall (QH)-superconductor (SC) junctions. To unambiguously detect AESs, we measure shot noise along with electrical conductance in a graphene-based QH-SC junction at integer filling ν=2. Remarkably, we find that the Fano factor of shot noise approaches half when the bias energy is less than the superconducting gap (2�), whereas it is close to zero above 2�. This is striking, given that, at the same time, the electrical conductance remains quantized at 2e2/h within and above 2�. A quantized conductance is expected to produce zero-shot noise due to its dissipationless flow. However, at a QH-SC interface, AESs carry the current in the zero-bias limit and an equal mixing of electron- and holelike states produces half of the Poissonian shot noise with quantized conductance. The observed results are in accord with our detailed theoretical calculations of electrical conductance and shot noise based on the nonequilibrium Green's function method in the presence of disorder. Our results pave the way in using shot noise as a detection tool in the search for exotic topological excitations in QH-SC hybrids. © 2021 American Physical Society.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to Authors
Keywords: Electric conductance; Graphene; Interface states; Quantum theory; Topology, Detection tools; Electrical conductance; Non equilibrium green's function method; Quantized conductance; Quantum hall; Superconducting gaps; Theoretical calculations; Topological excitations, Shot noise
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 02 Dec 2021 13:00
Last Modified: 02 Dec 2021 13:00
URI: http://eprints.iisc.ac.in/id/eprint/70085

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