Basic properties of an rf SQUID involving two Josephson junctions connected in series

We have studied the basic characteristics of a radio frequency superconducting quantum interference device (rf SQUID) involving two Josephson junctions connected in series, the case for the widely used grain boundary junction (GBJ) rf SQUID. It is found that the SQUID properties are determined mainly by the weaker junction when the critical current of the weaker junction is much lower than that of the other junction. Otherwise, the effect of the other junction is not negligible. We also find that only when the hysteresis parameter β is less than 1-α, where α is the critical current ratio of the two junctions, will the SQUID operate in the nonhysteretic mode.     

双结π环自发磁化的研究

研究了超导双结π环的自发磁化现象.讨论了双结π环可能发生自发磁化的条件，指出了自发磁化条件不仅与电感参数β有关，而且与两结临界电流之比有关.并通过分析自由能证明自发磁化是稳定的状态.最后给出了讨论结果和渐进行为. 关键词： 双结π环 自发磁化 自由能     

新型的高温超导薄膜梳齿谐振器

本文报导了一种新型结构的高温超导薄膜梳齿谐振器.我们通过改变谐振器梳齿的长度,使谐振器的谐振频率可以从800MHz到1300MHz左右,这正是我们研制的Hi-Tc rf SQUID所需要的两个频段.我们对这种新型谐振器的谐振频率与几何尺寸的关系进行了数值拟合.测试了使用该种新型谐振器的Hi-Tc rf SQUID的噪声.     

摆动镜随动系统的设计与实现

光学摆镜是某红外目标干扰模拟器的核心部件,要求光学摆镜运动位置控制精度高、响应时间短。在系统建模和仿真分析的基础上,提出了一种光学摆镜伺服控制系统的设计和实现方法。光学摆镜伺服控制系统是以DSP为核心,采用了位置控制回路和速度控制回路双闭环数字PID算法,利用有限转角力矩电机作为控制系统的执行机构,使用高精度旋转变压器作为控制系统的测量部件。实验结果表明,该伺服系统控制精度高,响应时间短,具有很好的工程应用前景。     

含有两个约瑟夫森结的射频SQUID的本征磁通噪声

我们研究了双结射频超导量子干涉器件（rf SQUID）的含时特性，给出了总磁通的动力学方程，并分析了在回滞模式和非回滞模式下的本征磁通噪声。结果显示：两个结的临界电流差别越大则越有助于获得小的本征噪声，在这种情况下，双结rf SQUID的本征磁通噪声会比单结rf SQUID的噪声稍大，但不超过一个数量级。     

Mode couplings of a semiconductor nanowire scanning across a photonic crystal nanocavity

The position-dependent mode couplings between a semiconductor nanowire(NW) and a planar photonic crystal(PPC) nanocavity are studied. By scanning an NW across a PPC nanocavity along the hexagonal lattice's Γ– M and M – K directions, the variations of resonant wavelengths, quality factors, and mode volumes in both fundamental and second-order resonant modes are calculated, implying optimal configurations for strong mode-NW couplings and light-NW interactions. For the fundamental(second-order) resonant mode, scanning an NW along the M – K(Γ– M) direction is preferred, which supports stronger light-NW interactions with larger NW-position tolerances and higher quality factors simultaneously. The simulation results are confirmed experimentally with good agreements.