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TT: Fachverband Tiefe Temperaturen

TT 58: Quantum Transport and Quantum Hall effects (joint session HL/TT)

TT 58.2: Talk

Wednesday, March 11, 2026, 15:15–15:30, POT/0006

Gate-tunable isospin switching in graphene Mach-Zehnder electronic interferometers — •Antonio Lacerda-Santos, Lilian Seyve, Yassine Setti, Bikash Barik, Leo Pugliese, Preden Roulleau, and Cosimo Gorini — SPEC, CEA, CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France

Graphene has become an exciting platform for electron (quantum) optics experiments [1]. Compact electronic interferometers can be realised via p-n interfaces, which in quantizing magnetic fields host counter-propagating chiral edge states. In a paradigmatic architecture with a single junction, such quantum Hall states form a Mach-Zehnder interferometer [2, 3]. The precise position of such edge states is set by the electrostatics of a given device [4], which can be determined to great accuracy with the self-consistent Schrödinger-Poisson solver Pescado [5].

We perform electrostatic and quantum transport simulations accompanying conductance measurements in a graphene Mach-Zehnder interferometer, and show that remote gates can be used to control the position of the p-n junction on sub-nanometer scales. Such a fine control does not meaningfully affect the edge state positions and lengths, but induces valley-isospin oscillations. The interferometer thus behaves as a tunable valley-isospin transistor.

[1] H. Chakraborti et al., J.Phys.:Condens.Matter 36 (2024) 393001 [2] D.S.Wei et al, Science Advances 3, e1700600 (2017) [3] M. Jo et al, PRL 126, 146803 (2021) [4] I.M. Flor et al, PRB 105, L241409 (2022) [5] A. Lacerda-Santos, arXiv:2507.03131v1

Keywords: Graphene; Mach-Zehnder; Valley-Isospin; Schrödinger-Poisson