约瑟夫森结中周期解及其稳定性的解析分析

针对交流激励下电阻-电容分路的约瑟夫森结,采用增量谐波平衡法推导了系统中周期解的解析表达式,并运用Floquet理论分析了周期解的稳定性.发现系统处于稳定周期状态的同时,还存在着丰富的不稳定周期解.通过计算Floquet乘数,得到了系统稳定周期解失稳时的临界参数值,并确定了系统发生的分岔类型,从理论上证明了系统随激励电流幅值的增加由倍周期分岔通向混沌.解析分析与数值计算结果具有很好的一致性.关键词：约瑟夫森结增量谐波平衡法周期解分岔

Analytical analysis of periodic solution and its stability in Josephson junction

Analytical expressions of periodic solutions in rf-biased resistively-capacitively-shunted Josephson junction were derived by incremental harmonic balance method, and the stability of the periodic solutions was investigated using Floquet theory. We fownd that while the system is in stable periodic states, plentiful unstable periodic orbits still exist in the system. Critical parameter values for which the stable periodic solutions of the system lose their stability are obtained and the type of bifurcation is determined by computing the Floquet multipliers. We have also theoretically confirmed the period-doubling-route to chaos with increasing amplitude of driving current, which acts as the control parameter in the system. The results from analytical analysis coincide with that from numerical simulation.