Non-Hermitian topology in a multi-terminal quantum Hall device
Kyrylo Ochkan, Raghav Chaturvedi, Viktor Könye, Louis Veyrat, Romain Giraud, D. Mailly, A. Cavanna, U. Gennser, Ewelina M. Hankiewicz, B. Büchner, Jeroen van den Brink, Joseph Dufouleur, Ion Cosma Fulga
Abstract
Abstract Quantum devices characterized by non-Hermitian topology are predicted to show highly robust and potentially useful properties for precision sensing and signal amplification. However, realizing them has remained a daunting experimental task, as non-Hermiticity is often associated with gain and loss, which would require precise tailoring to produce the signatures of non-trivial topology. Here, instead of gain and loss, we use the non-reciprocity of quantum Hall edge states to directly observe non-Hermitian topology in a multi-terminal quantum Hall ring. Our transport measurements evidence a robust, non-Hermitian skin effect, characterized by currents and voltages showing an exponential profile that persists across Hall plateau transitions away from the regime of maximum non-reciprocity. Our observation of non-Hermitian topology in a quantum device introduces a scalable experimental approach to construct and investigate generic non-Hermitian systems.