Fast generating W state of three superconducting qubits via Lewis–Riesenfeld invariants

We propose a scheme for a fast generating three-qubit W state in a superconducting system by using a technique of shortcuts to adiabaticity, Lewis–Riesenfeld invariants. Three identical superconducting qubits(SQs) are connected by two coplanar waveguide resonators(CPWRs) capacitively. Under a certain limit condition, we convert the complicated SQ system into a simple three-state system. By designing experimentally accessible harmonic pulses, a three-SQ W state is implemented with quite short operation time and high fidelity. Numerical simulations prove that the scheme is robust against the parameter deviation. In addition, we also give detailed discussion about the scheme robustness against decoherence.     

编组站调度计划0-1规划法

针对货车编组问题,采用半分离式两阶段0-1线性规划模型对各阶段联合求解,对局部最优解采用调度时序图可视化表述.首先,对无、有调车辆分离,无调车采用启发式安排.有调车推峰顺序可以转化为零件加工问题,以驼峰总工作量最大、等待时间最小为目标建立模型I.列车解体时间与解体方向数成正比增长,但在未确定具体解体方案时无法确定(即模型I的独立),通过在模型II中对解体时间模糊化来处理两步独立的缺陷,从而达到两步规划的连续特性.车辆新编,决策变量属于多维结构,通过将多维稀疏变量转化为一维序列,有效解除其稀疏特性,形成二维决策变量建立规划模型II直接求解.其次,通过仿真创建模拟数据,运用主模型求解,得到了驼峰是编组站主要瓶颈的结论.最后,我们还对铁路资源的紧缺性、编组效率建模给出了较详细改进措施.     

1.3μm量子通讯波段强度差压缩光的实验产生

利用输出波长为1.3μm的全固态单频红外激光器进行外腔倍频,获得稳定的外腔倍频红光激光输出,产生的红光用来泵浦由Ⅱ类非临界相位匹配的LBO晶体构建的光学参量振荡腔。在光学参量振荡器非简并运转的情况下,观察到了信号光和闲置光的强度差起伏的关联,实测强度差噪声压缩度为3.9 dB。