Optomechanical realization of the bosonic Kitaev-Majorana chain

TL;DR

This paper demonstrates a bosonic analogue of the fermionic Kitaev chain using nano-optomechanical systems, revealing unique topological phenomena, phase transitions, and enhanced sensing capabilities due to non-Hermitian topology.

Contribution

It introduces a bosonic version of the Kitaev-Majorana chain in optomechanics, showing novel topological effects and non-Hermitian phase transitions not present in fermionic systems.

Findings

Observation of quadrature-dependent chiral amplification

Exponential scaling of gain with system size

Enhanced response to perturbations due to non-Hermitian topology

Abstract

The fermionic Kitaev chain is a canonical model featuring topological Majorana zero modes. We report the experimental realization of its bosonic analogue in a nano-optomechanical network where parametric interactions induce two-mode squeezing and beamsplitter coupling among the nanomechanical modes, equivalent to hopping and superconductor pairing in the fermionic case, respectively. We observe several extraordinary phenomena in the bosonic dynamics and transport, including quadrature-dependent chiral amplification, exponential scaling of the gain with system size, and strong sensitivity to boundary conditions. Controlling the interaction phases and amplitudes uncovers a rich dynamical phase diagram that links the observed phenomena to non-Hermitian topological phase transitions. Finally, we present an experimental demonstration of an exponentially enhanced response to a small perturbation as a consequence of non-Hermitian topology. These results represent the demonstration of a novel synthetic phase of matter whose bosonic dynamics do not have fermionic parallels, and establish a powerful system to study non-Hermitian topology and its applications in signal manipulation and sensing.