在一个磁通量子内dc Josephson电流阶梯或振荡效应的物理本质

本文分析了放置于高Q谐振腔中的Josephson结、双结SQUID和单结超导环,当其Josephson频率ω=2eV₀/h和腔的本征频率相等时,Josephson电流在一个磁通量子内可以产生多次阶梯或振荡的物理本质。指出对于Josephson结或双结SQUID,当ω=ω_r时,被激发起的腔的本征振荡将反馈辐照结或SQUID,反馈场的频率作用使Josephson电流产生一般地感应台阶;而反馈场的振幅是受到外磁场调制的,当这种调制作用使反馈场振幅的空间部分与辐射场的空间部分匹配时,则引起电流在一个磁通量子内产生一系列的新的阶跃。对单结超导环,当nω=ω_r时,被激发起的腔的振荡反馈辐照作用将迫使其超流电流产生周期小于φ₀的振荡。关键词：

THE PHYSICAL ESSENCE FOR THE STEP STRUCTURES OR OSCILLATING EFFECT OF DC JOSEPHSON CORRENT WITHIN ONE FLUX QUANTUM PERIOD φ0

In this paper, we analyzed the physical essence for producing a series of step structures or oscillating effect of dc Josephson current within one flux quantum period φ₀ by placing Josephson junction, two-junction SQUID and the supercon ducting ring containing a single junction in a cavity, when one of the eigen-frequencies ω_r of which is equal to Josephson frequency and the Q-Value is sufficiently high. We point out that the frequency effect of the feedback field would produce a series of induced steps for Josephson junction or two-junction SQUID, as ω = ω_r, the oscillating electric-magnetic field excited by the junction current reacts on the junctions themself. Furthermore, a series of new step structures should occur within the φ₀ since the amplitude of the feedback field is modulated by applied magnetic field as the modulation of the amplitude of the feedback field is coupled with that of the radiation. For the superconducting ring containing a single junction, as nω=ω_r, the feedback radiation of stationary electric-magnetic wave will give rise constrained oscillation of the supereurrent with a smaller period than the φ₀.