Landau-Zener without a Qubit: Multiphoton Sidebands Interaction and Signatures of Dissipative Quantum Chaos

Landau-Zener-Stückelberg-Majorana (LZSM) interference occurs when qubit parameters are periodically modulated across avoided level crossings. In this work [1], we explore this phenomenon in nonlinear multilevel bosonic systems, where interference is influenced by multiple energy levels and cannot be described by a level crossing between only two states. We fabricate two superconducting resonators with flux-tunable Josephson junction arrays. The first device, exhibiting weak nonlinearity, behaves like a linear resonator under weak driving but shows LZSM interference analogous to two-level systems. When subjected to a stronger drive, nonlinear effects become significant, and the interference pattern departs from that observed in two-level systems. We demonstrate that, when two or more LZSM interference peaks merge, dissipative quantum chaos emerges [2]. In the second device, where nonlinearity exceeds photon-loss rates, we observe additional LZSM peaks due to Kerr multiphoton resonances. According to Floquet theory, these resonances represent synthetic modes of coupled nonlinear cavities, revealing effective coupling as modulation parameters vary. Our findings advance the understanding of LZSM physics and emphasize the control of nonlinear Floquet states and the emergence of chaos in engineered systems, with significant implications for novel applications in quantum dynamics and quantum control.



[1] L. Peyruchat et al., arXiv:2404.10051 (2024)

[2] F. Ferrari et al., arXiv:2305.15479 (2023)