Observation of the non-Hermitian skin effect and Fermi skin on a digital quantum computer
R. Shen, Tianqi Chen, Bo Yang, Ching Hua Lee
Abstract
Lately, the non-Hermitian skin effect (NHSE) has been demonstrated in various classical metamaterials and even ultracold atomic arrays. Yet, its interplay with many-body dynamics have never been experimentally investigated. Here, we report the observation of the NHSE and its many-fermion analog on a universal quantum processor. To implement NHSE accumulation on a quantum computer, the time-evolution circuit not only needs to be non-reciprocal and non-unitary, but must also contain sufficiently many lattice qubits. We demonstrate this by systematically post-selecting ancilla qubits, as demonstrated through two paradigmatic non-reciprocal models on noisy quantum processors, with clear signatures of asymmetric spatial propagation and many-body “Fermi skin” accumulation. To minimize errors from inevitable device noise, time evolution is performed using trainable, variationally optimized quantum circuits. Our demonstration represents an important step in the quantum simulation of non-Hermitian lattices on present-day quantum hardware, and can be readily generalized to more sophisticated many-body models. Non-Hermitian skin effect, a phenomenon where eigenstates accumulate at the boundaries of a non-Hermitian system, has been observed in various platforms but primarily at the single particle level. Here the authors demonstrate the interplay of this effect with many-body physics on a superconducting quantum processor.