Asymmetric-gate Mach--Zehnder interferometry in graphene: Multi-path conductance oscillations and visibility characteristics

Abstract: Graphene provides an excellent platform for investigating electron quantum interference due to its outstanding coherent properties. In the quantum Hall regime, Mach--Zehnder (MZ) electronic interferometers are realized using p--n junctions in graphene, where electron interference is highly protected against decoherence. In this work, we present a phenomenological framework for graphene-based MZ interferometry with asymmetric p--n junction configurations. We show that the enclosed interferometer area can be tuned by asymmetric gate potentials, and additional MZ pathways emerge in higher-filling-factor scenarios, e.g. $\left(\nu_{n},\nu_{p}\right)=\left(-3,+3\right)$. The resulting complicated beat oscillations in asymmetric-gate MZ interference are efficiently analyzed using a machine-learning--based Fourier transform, which yields improved peak-to-background ratios compared to conventional signal-processing techniques. Furthermore, we examine the impact of the asymmetric gate on the interference visibility, finding that interference visibility is enhanced under symmetric gate conditions.