Quantum simulation of the bosonic Kitaev chain

Superconducting quantum circuits provide a natural platform to analog-simulate lattice models with topological phenomena. The bosonic Kitaev chain (BKC), a 1D tight-binding model with both nearest-neighbor hopping and pairing terms, exhibits features associated with non-Hermitian systems (chiral transport and sensitivity to boundary conditions) despite being described by a Hermitian Hamiltonian. Using a multimode superconducting parametric cavity, the authors implement the BKC in synthetic frequency dimensions: lattice sites map to cavity modes, while in situ tunable complex hopping and pairing terms are engineered by parametric pumping at mode-difference and mode-sum frequencies, respectively. They experimentally demonstrate precursors of nontrivial topology and the non-Hermitian skin effect, including phase-dependent chiral transport, quadrature wavefunction localization, and strong boundary-condition sensitivity. This establishes a route to exploring many-body non-Hermitian quantum dynamics without dissipation.

Jamal H. Busnaina, Zheng Shi, Alexander McDonald, Dmytro Dubyna, Ibrahim Nsanzineza, Jimmy S. C. Hung, C. W. Sandbo Chang, Aashish A. Clerk, Christopher M. Wilson