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121.
A transition between energy levels at an avoided crossing is known as a Landau–Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stückelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau–Zener–Stückelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory. 相似文献
122.
A.I. Agafonov 《Physics letters. A》2010,374(23):2383-2387
For the first time the differential cross section for the inelastic magnetic neutron scattering by superconducting rings is derived taking account of the interaction of the neutron magnetic moment with the magnetic field generated by the superconducting current. Calculations of the scattering cross section are carried out for cold neutrons and thin film rings from type-II superconductors with the magnetic fields not exceeding the first critical field. 相似文献
123.
Issarachai Ngamroo 《Physica C: Superconductivity and its Applications》2010,470(22):1986-1993
It is well known that the superconducting magnetic energy storage (SMES) is able to quickly exchange active and reactive power with the power system. The SMES is expected to be the smart storage device for power system stabilization. Although the stabilizing effect of SMES is significant, the SMES is quite costly. Particularly, the superconducting magnetic coil size which is the essence of the SMES, must be carefully selected. On the other hand, various generation and load changes, unpredictable network structure, etc., cause system uncertainties. The power controller of SMES which is designed without considering such uncertainties, may not tolerate and loses stabilizing effect. To overcome these problems, this paper proposes the new design of robust SMES controller taking coil size and system uncertainties into account. The structure of the active and reactive power controllers is the 1st-order lead-lag compensator. No need for the exact mathematical representation, system uncertainties are modeled by the inverse input multiplicative perturbation. Without the difficulty of the trade-off of damping performance and robustness, the optimization problem of control parameters is formulated. The particle swarm optimization is used for solving the optimal parameters at each coil size automatically. Based on the normalized integral square error index and the consideration of coil current constraint, the robust SMES with the smallest coil size which still provides the satisfactory stabilizing effect, can be achieved. Simulation studies in the two-area four-machine interconnected power system show the superior robustness of the proposed robust SMES with the smallest coil size under various operating conditions over the non-robust SMES with large coil size. 相似文献
124.
K. Yokoyama T. Oka K. Noto 《Physica C: Superconductivity and its Applications》2010,470(20):1201-1206
We study the construction of superconducting permanent magnets by RE123 bulk materials and the investigation of these industrial applications such as a magnetic separation. A bulk magnet can generate strong magnetic fields exceeding 2 T, which is the limit of ordinary iron-cored electromagnets, in a compact device with a low running cost. A magnetic field distribution of the bulk magnet is a cone shape, and it contributes to an increase of magnetic force which is proportional to the product of a magnetic field and its gradient. It is important to evaluate magnetic force when the application of the bulk magnet is discussed. In this paper, two Gd123 bulk materials of 65 mm in diameter were magnetized using a pair of superconducting bulk magnet system and three-axis components of magnetic flux density (Bx,⋅By, and Bz) in an open space between the magnetic poles were scanned with pitch of 2 mm in each direction. From these measured data, the axial and radial components of magnetic force factor, Bz⋅dBz/dz and Br⋅dBr/dr, were calculated. At 10 mm gap, the Bz⋅dBz/dz value reached 180.6 T2/m for a field of 2.33 T, which is comparable to Bz = 6.76 T for a common 10 T–100 mm∅ superconducting magnet. 相似文献
125.
M. Inoue R. Fuger K. Higashikawa T. Kiss M. Namba S. Awaji K. Watanabe A. Ibi S. Miyata Y. Yamada T. Izumi 《Physica C: Superconductivity and its Applications》2010,470(20):1292-1294
We have investigated current transport property in Gd1Ba2Cu3O7−δ coated conductor with artificial pinning centers in a wide range of temperature, magnetic field, B up to 27 T, and field angle. Due to the additional c-axis correlated pins, critical current density, Jc in B//c was enhanced and the improvement was observed in wide range of B. On the other hand, around B⊥c below 65 K, the angular dependence of n-value showed a valley-like behavior, although the Jc was increasing. In addition, the temperature dependence of the pinning force density defined as Jc × B was not scaled on an expected master curve. These results indicate the pinning in B⊥c is governed by different mechanism below 65 K and high magnetic field. 相似文献
126.
首先,提出了一个改进超导电路结构,此结构能实现任意两个量子比特的相互作用而非近邻作用,长程作用是实现量子计算所必需的,此结构能用目前的技术制作。其次,基于此结构提出了Grover搜索算法实现的物理方案。由于能实现任意两量子比特之间的控制相位门,所以多比特Grover搜索算法也能实现,以满足各种量子计算的需要。此方案是一个基于电流控制的超导电荷比特网络结构的可扩展及易实现的Grover搜索算法实现方案。 相似文献
127.
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129.
针对超导球体和圆形线圈之间的力的作用,介绍了一种简化而有效的计算悬浮力的方法。在此基础上,对线圈和超导球体的几何形状尺寸以及两者之间的相对位置关系对悬浮力的影响进行了综合的分析和讨论;对悬浮力在随着线圈和超导球体的具体参数的变化规律做了定量的分析。总结出的结论为超导悬浮系统的分析和设计提供重要的参照。 相似文献
130.
在晶界夹角分别为 2 4°,3 2°的 YSZ双晶基片上 ,制备了高 Tc Gd Ba2 Cu3O7-δ双晶超导薄膜 ,采用光刻技术在晶界上刻出了两种不同尺寸的双晶晶界结 ,在液氮温度下观测了结的直流 I-V特性 ,用 1 0 GHz微波辐照双晶结结区 ,观察到了结临界电流的压缩和 Shapiro台阶 ,表明双晶结具有约瑟夫逊弱连接行为。用上述双晶结进行光探测 ,用波长为 0 .63 2 8μm的 He-Ne激光器辐照结区 ,系统的观测了其光响应特性 ,结果如下 :噪声等效功率 NEP =1 .9× 1 0 - 1 3W,归一化探测率 D*=5.3× 1 0 9cm Hz12 W- 1 ,响应率 Rv =4 .2× 1 0 7V/W,响应时间 τ<6.3 5× 1 0 - 7s 相似文献