Chalmers University of Technology, Department of Physics, SE-412 96 Göteborg, Sweden.
Sci Rep. 2017 Jan 25;7:41313. doi: 10.1038/srep41313.
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 an otherwise linear oscillator 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.
它是各种领域中不可或缺的理论工具。众所周知，通过与另一个动力系统的相互作用，原本线性的振荡器可以获得新颖的非线性特征。我们研究了这样一个相互作用的系统：一个超导 LC 电路与超导量子干涉装置（SQUID）的分布式耦合。我们发现 SQUID 的相位表现为一个经典的二能级系统，其两个状态对应于 LC 谐振器的一个线性和一个非线性区域。结果，电路对强迫的响应可以变得多稳定。非线性的强度可以通过系统中的噪声水平来调节，并且随着噪声的降低而增加。这种可调谐的非线性可能在敏感检测领域中找到应用，而对经典谐振子的深入了解对于研究 Jaynes-Cummings 系统的量子到经典的交叉点是相关的。
