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접속링크: https://us06web.zoom.us/j/86515148802?pwd=V6NBfBbHbZhC2XYLDqawOriaC64xbN.1
Zoom 회의 ID: 865 1514 8802

2D material based quantum electronic devices

Myunglae Jo
Department of Physics, Kyungpook National University

Abstract

The concept of van der Waals heterostructure enables us to harness exotic properties of 2D materials in their cleanest limit. Thanks to such progress, recently several studies have demonstrated electron quantum optics devices with graphene by exploiting the wave nature of electrons in the quantum Hall regime. [1, 2, 3] Previously this had been only possible with high-mobility GaAs 2D electron gas. Here, we present the realization of a graphene Mach-Zehnder interferometer with fully tunable beam splitters. [1] Coherent splitting and mixing of the copropagating but opposite-valley (with the same spin) channels of the PN interface are independently achieved by tuning the filling factors below, above, and around the flake of graphene in the quantum Hall regime. Measuring the modulation of the electrical current through the PN junction reveals a quantum interference pattern. Next, using this graphene Mach-Zehnder interferometer as a sensitive quantum coherent detector we studied the physics of the magnons in a quantum Hall ferromagnet. [2] Spin-waves are electrically generated and propagate toward the interferometer through the insulating bulk. Electric dipoles induced by magnons change the visibility and phase of interference patterns of the interferometer. These experiments provide an additional material platform in the field of electron quantum optics and new way to study the fundamental properties of quantum Hall ferromagnet.
 

References
[1]    M. Jo, P. Brasseur, A. Assouline, et al. Quantum Hall Valley Splitters and a Tunable Mach-Zehnder Interferometer in Graphene. Physical Review Letters, 126, 146803 (2021)
[2]    Déprez, C., Veyrat, L., Vignaud, H. et al. A tunable Fabry–Pérot quantum Hall interferometer in graphene. Nature Nanotechnology. 16, 555–562 (2021)
[3]    Ronen, Y., Werkmeister, T., Haie Najafabadi, D. et al. Aharonov–Bohm effect in graphene-based Fabry–Pérot quantum Hall interferometers. Nature Nanotechnology. 16, 563–569 (2021)
[4]    A. Assouline, M. Jo, P. Brasseur et al. Excitonic nature of magnons in a quantum Hall ferromagnet. Nature Physics 17, 1369–1374 (2021)