Noise-tunable nonlinearity in a dispersively coupled diffusion-resonator system using superconducting circuits

TL;DR

This paper demonstrates how a superconducting circuit system exhibits noise-tunable nonlinearity, with potential applications in sensitive detection and insights into quantum-classical transitions.

Contribution

It introduces a dispersively coupled superconducting circuit system where nonlinearity is tunable via noise levels, revealing new control mechanisms for oscillator behavior.

Findings

Nonlinear features emerge through interaction with a two-level system.

Nonlinearity strength increases as noise decreases.

System exhibits multistability in response to forcing.

Abstract

The harmonic oscillator is one of the most widely used model systems in physics: an indispensable theoretical tool in a variety of fields. It is well known that otherwise linear oscillators can attain novel and nonlinear features through interaction with another dynamical system. We investigate such an interacting system: a superconducting LC-circuit dispersively coupled to a superconducting quantum interference device (SQUID). We find that the SQUID phase behaves as a classical two-level system, whose two states correspond to one linear and one nonlinear regime for the LC-resonator. As a result, the circuit's response to forcing can become multistable. The strength of the nonlinearity is tuned by the level of noise in the system, and increases with decreasing noise. This tunable nonlinearity could potentially find application in the field of sensitive detection, whereas increased understanding of the classical harmonic oscillator is relevant for studies of the quantum-to-classical crossover of Jaynes-Cummings systems.