相移控制下XX自旋链中的量子态传递

研究了由Aharonov-Casher相互作用产生的相移对XX自旋链中量子态传递的影响。对信道的纠缠度及传递量子态的保真度进行数值模拟后发现,控制相移的方法可以有效抵抗信道的消相干作用,显著提高自旋链中量子比特间的纠缠度及量子态的保真度。此外,量子态发送端与接收端之间相对位置的不同也会影响纠缠度和保真度的大小,在包含偶数个自旋格点的环形自旋链中,当发送端与接收端处在直径上相对的位置时,接收端的纠缠度和量子态传递的保真度可以达到最大值。     

基于遗传算法的电动汽车换电站经济运行

在现有的电池技术和充电条件下,快换式充电站成为国内纯电动公交最主要的能量补给摸式。针对电池组充电电费过高和增加配电网峰谷差的问题,以及换电站内快换工位和备用电池空闲的情况,在保证车辆正常运营的前提下,以充电站内全天充电电费最低为目标,建立了充电变功率工况下基于分时电价的换电站经济运行模型,通过遗传智能优化算法合理安排电池组的开始充电时间,降低充电电费,从而实现换电站的经济运行。分别基于北京北土城充电站和上海世博会充电站的实际数据和统计结果进行算例仿真,验证了算法的有效性。结果表明,该算法不仅能降低充电站充电电费,还能降低充电站白天对配电网的负荷压力,补充夜间负荷,减小配电网的峰谷差,在实现充电站经济运行的同时还有助于配电网的经济运行。     

Quantifying quantumness of correlations using Gaussian Rényi-2 entropy in optomechanical interfaces

Using the Gaussian Rényi-2 entropy, we analyse the behaviour of two different aspects of quantum correlations (entanglement and quantum discord) in two optomechanical subsystems (optical and mechanical). We work in the resolved sideband and weak coupling regimes. In experimentally accessible parameters, we show that it is possible to create entanglement and quantum discord in the considered subsystems by quantum fluctuations transfer from either light to light or light to matter. We find that both mechanical and optical entanglement are strongly sensitive to thermal noises. In particular, we find that the mechanical one is more affected by thermal effects than that optical. Finally, we reveal that under thermal noises, the discord associated with the entangled state decays aggressively, whereas the discord of the separable state (quantumness of correlations) exhibits a freezing behaviour, seeming to be captured over a wide range of temperature.     

新一代的计算机

本文简要地介绍了超导计算机,光计算机和量子计算机的原理和优点。并介绍了量子计算机的一些基本概念：量子叠加,量子纠缠,量子位和量子逻辑门。     

Time evolution of entanglement and bistability of two coupled quantum dots in a driven cavity

Abstract

The time evolution of entanglement between two quantum dots (QDs) trapped inside a cavity driven by a coherent quantized field is studied. In the presence of dissipation, entanglement shows many interesting features such as sudden death and revival, and finite steady state value after sudden death. We also investigate dependence of entanglement on dot variables and its relation to bistability. It is found that entanglement vanishes when the cavity field intensity approaches the upper branch of the bistability curve. When the cavity is driven by a modulated field in the presence of dissipation, it can periodically generate entanglement, which is much larger than the maximum value attained in the steady-state for this system but the dots are never fully entangled.     

Photon statistics anomalies in adiabatic transfer between two cavity modes

Adiabatic transfer between two degenerate cavity modes is investigated theoretically using a counter-intuitive pulse sequence. Several measures of successful state transfer are shown to correlate strongly with anomalous values of the photon statistics of the initial mode. The detailed behaviour of theses anomalies originate from the way the state approaches vacuum and their features are found to give a good indication of the effciency and robustness of the state transfer.     

Crystal Structure Determination and Mutagenesis Analysis of the Ene Reductase NCR

The crystal structure of the “ene” nicotinamide‐dependent cyclohexenone reductase (NCR) from Zymomonas mobilis (PDB ID: 4A3U) has been determined in complex with acetate ion, FMN, and nicotinamide, to a resolution of 1.95 Å. To study the activity and enantioselectivity of this enzyme in the bioreduction of activated α,β‐unsaturated alkenes, the rational design methods site‐ and loop‐directed mutagenesis were applied. Based on a multiple sequence alignment of various members of the Old Yellow Enzyme family, eight single‐residue variants were generated and investigated in asymmetric bioreduction. Furthermore, a structural alignment of various ene reductases predicted four surface loop regions that are located near the entrance of the active site. Four NCR loop variants, derived from loop‐swapping experiments with OYE1 from Saccharomyces pastorianus, were analysed for bioreduction. The three enzyme variants, P245Q, D337Y and F314Y, displayed increased activity compared to wild‐type NCR towards the set of substrates tested. The active‐site mutation Y177A demonstrated a clear influence on the enantioselectivity. The loop‐swapping variants retained reduction efficiency, but demonstrated decreased enzyme activity compared with the wild‐type NCR ene reductase enzyme.     

Nanowrinkled and Nanoporous Polyethylene Membranes Via Entanglement Arrangement Control

Crystalline homopolymers, including polyethylene (PE), which has the simplest architecture, form a nanometer‐sized combination of crystalline and amorphous components, but their arrangement control, similar to self‐assembled phase‐separation of block‐copolymers, is usually difficult. However, molecular entanglements trapped between crystalline and amorphous components of homopolymers coincide with the segmental linking points on the interfaces of the microphase separation for block copolymers. Nanowrinkled PE membranes are prepared with a network of 30 nm‐thick homogeneous lamellae using a novel entanglement control technique composed of biaxial melt‐drawing and melt‐shrinking procedures, which are limited for highly entangled ultrahigh molecular weight materials. Such a network arrangement of nanowrinkling lamellae spreading on membrane surface and also across the membrane thickness improves the mechanical properties of both tensile strength and tearing strength. Subsequent cold‐drawing causes delamination of the lamellar interfaces, leading to the resultant nanoporous morphology composed of passing‐through channels that are several tens of nanometers in diameter, without any solvent processing.     

地磁暴引起的埋地管道管地电位“波节”和“纠缠”分布特征

磁暴在大地介质中感应生成地电场和地磁感应电流，进而导致长输埋地管道的管地电位偏离安全范围，加剧管道的腐蚀。西气东输二线西部管道多处管地电位监测数据显示，不同位置的管地电位具有幅度不同且变化趋势相同或相反的特征。对该区域进行三维大地电导率建模，应用2016年9月28日乌鲁木齐地磁台监测数据作为电磁激励，结合Galerkin有限元法与LZS-DSTL理论，计算了该区域管地电位的时空分布，通过与监测数据对比，验证了该方法的有效性。通过对管地电位时空分布特征分析，提出了管地电位空间分布的"波节"和时间变化的"纠缠"概念，根据理论分析和现场管道监测数据揭示了二者之间的内在联系，进一步研究了影响管地电位"波节"分布的重要因素。研究结果表明，管地电位"波节"和"缠绕"现象是普遍存在的，"波节"既是管地电位的空间分布过零点，又是管地电位时域变化趋势的分界点；管道地磁感应电流的极值位置往往与管地电位"波节"相对应，为管道阴极保护装置的合理配置提供了理论依据。     

沸水处理对PAC风干拉伸纤维结构与性能的影响

研究了沸水处理时间不同的共聚丙烯腈风干拉伸纤维中缠结的变化及其对纤维性能的影响。随沸水处理时间增加,样品解缠能先从小到大继而由大变小,再而由小变大并趋于平衡。沸水处理时间较短的样品主要是无定形区内取向对纤维的机械性能产生影中,随沸水处理时间增加,无定形区内取向下降,样品的断裂伸长、结强随之上升,断裂强度和初始模量随之下降。当沸水处理时间继续增加时,样品的取向基本不变,解缠能逐渐增加,样品的断裂伸长、结强和断裂强度随之下降,初始模量随之上升,表明样品内部缠结对纤维机械性能产生了影响。