Quantum Simulation of the Bosonic Kitaev Chain

TL;DR

This paper demonstrates the implementation of a bosonic Kitaev chain using superconducting circuits, revealing non-Hermitian topological phenomena like chiral transport and boundary sensitivity, advancing quantum simulation capabilities.

Contribution

It introduces a novel experimental realization of the bosonic Kitaev chain in superconducting circuits, enabling exploration of non-Hermitian topological effects in quantum systems.

Findings

Observation of chiral transport in the bosonic chain

Detection of quadrature wavefunction localization

Demonstration of sensitivity to boundary conditions

Abstract

Superconducting quantum circuits are a natural platform for quantum simulations of a wide variety of important lattice models describing topological phenomena, spanning condensed matter and high-energy physics. One such model is the bosonic analogue of the well-known fermionic Kitaev chain, a 1D tight-binding model with both nearest-neighbor hopping and pairing terms. Despite being fully Hermitian, the bosonic Kitaev chain exhibits a number of striking features associated with non-Hermitian systems, including chiral transport and a dramatic sensitivity to boundary conditions known as the non-Hermitian skin effect. Here, using a multimode superconducting parametric cavity, we implement the bosonic Kitaev chain in synthetic dimensions. The lattice sites are mapped to frequency modes of the cavity, and the $\textit{in situ}$ tunable complex hopping and pairing terms are created by parametric pumping at the mode-difference and mode-sum frequencies, respectively. We experimentally demonstrate important precursors of nontrivial topology and the non-Hermitian skin effect in the bosonic Kitaev chain, including chiral transport, quadrature wavefunction localization, and sensitivity to boundary conditions. Our experiment is an important first step towards exploring genuine many-body non-Hermitian quantum dynamics.