Flux-modulated tunable interaction regimes in two strongly nonlinear oscillators

TL;DR

This paper demonstrates flux-controlled tunable interaction regimes in two nonlinear oscillators, enabling selective activation of photon-hopping, squeezing, and cross-Kerr interactions for advanced quantum simulation and oscillator dynamics studies.

Contribution

It introduces a scheme for selectively activating different interaction regimes between nonlinear oscillators using parametric modulation, expanding control in quantum simulation platforms.

Findings

Access to photon-hopping, two-mode squeezing, and cross-Kerr regimes.

Observation of level repulsion and attraction in nonlinear oscillators.

Demonstration of tunable interactions exceeding decay rates.

Abstract

The ability to efficiently simulate a variety of interacting quantum systems on a single device is an overarching goal for digital and analog quantum simulators. In circuit quantum electrodynamical systems, strongly nonlinear superconducting oscillators are typically realized using transmon qubits, featuring a wide range of tunable couplings that are mainly achieved via flux-dependent inductive elements. Such controllability is highly desirable both for digital quantum information processing and for analog quantum simulations of various physical phenomena, such as arbitrary spin-spin interactions. Furthermore, broad tunability facilitates the study of driven-dissipative oscillator dynamics in previously unexplored parameter regimes. In this work, we demonstrate the ability to selectively activate different dynamical regimes between two strongly nonlinear oscillators using parametric modulation. In particular, our scheme enables access to regimes that are dominated by photon-hopping, two-mode squeezing, or cross-Kerr interactions. Finally, we observe level repulsion and attraction between Kerr-nonlinear oscillators in regimes where the nonlinearities exceed the coupling strengths and decay rates of the system. Our results could be used for realizing purely analog quantum simulators to study arbitrary spin systems as well as for exploring strongly nonlinear oscillator dynamics in previously unexplored interaction regimes.