论文标题
磁涡质运动对不对称阵列中反向AC的效应的影响
The influence of magnetic vortices motion on the inverse ac Josephson effect in asymmetric arrays
论文作者
论文摘要
We report on the influence a preferential magnetic vortices motion has on the magnitude of the inverse ac Josephson effect (the appearance of dc current Shapiro steps) and the coherent operation of asymmetrical parallel arrays of YBaCuO Josephson junctions (JJ) irradiated with microwave (MW) radiation in the presence of an applied magnetic field B. The preferential direction of motion of the Josephson vortices is due to the不对称诱导的棘轮效应，并具有巨大的影响：对于特定的正直流偏置电流i时，磁通流是强大的多个明显的shapiro steps，与阵列的相干操作一致。这表明相关应用中MW的有效排放/检测。相比之下，当我们逆转I方向时，由于高度不连贯的操作，磁通量会减小，而shapiro步长被强烈抑制，这表明MW的发射/检测效率低下。值得注意的是，通过稍微更改B，情况逆转了：shapiro的步骤现在被抑制为正i，而对于反向电流-i，shapiro steps and被抑制了。我们的结果表明，优先的涡流流对由多个JJS或单个长JJ不对称偏置的超导装置的连贯MW操作产生非常显着的影响。对于磁通流振荡器的情况，这特别相关，用于亚terahertz集成收益器，通量驱动的Josephson（Travelling-Wave）参数放大器或通常在Shapiro Step区域中偏置电源在偏置电流下运行的芯片超导型MW发电机。
We report on the influence a preferential magnetic vortices motion has on the magnitude of the inverse ac Josephson effect (the appearance of dc current Shapiro steps) and the coherent operation of asymmetrical parallel arrays of YBaCuO Josephson junctions (JJ) irradiated with microwave (MW) radiation in the presence of an applied magnetic field B. The preferential direction of motion of the Josephson vortices is due to the asymmetry-induced ratchet effect and has a dramatic impact: for a particular positive dc bias current I when the flux-flow is robust multiple pronounced Shapiro-steps are observed consistent with a coherent operation of the array. This suggests an efficient emission/detection of MW in related applications. In contrast, when we reverse the direction of I, the flux-flow is reduced and the Shapiro-steps are strongly suppressed due to a highly incoherent operation that suggests an inefficient emission/detection of MW. Remarkably, by changing B slightly, the situation is reversed: Shapiro steps are now suppressed for a positive I, while well pronounced for a reverse current -I. Our results suggest that a preferential vortex-flow has a very significant impact on the coherent MW operation of superconducting devices consisting of either multiple JJs or a single long JJ asymmetrically biased. This is particular relevant in the case of flux-flow oscillators for sub-terahertz integrated-receivers, flux-driven Josephson (travelling-wave) parametric amplifiers, or on-chip superconducting MW generators which usually operate at bias currents in the Shapiro step region.
