Producing GHZ state of nitrogen-vacancy centers in cavity QED

Abstract

We propose a scheme to generate the GHZ state of nitrogen-vacancy centers coupled to a whispering-gallery mode cavity. The implemented evolution is independent of the cavity field state with the assistance of a strong classical field, and thus not sensitive to the thermal state of the cavity. Meanwhile, it is fast compared to the convectional dispersive interaction induced operation in a cavity-assisted system. The scheme is readily scalable to the multiqubit scenario.     

多孔金属的固相制备方法及应用

随着社会的不断发展,多孔金属材料的研发和应用得到了广泛的关注.在众多金属多孔材料的制备方法中,固相制备在商业生产中应用最为广泛.本文总结了固相制备金属多孔材料的工艺方法,介绍了其工艺过程,阐述了制备原理、优缺点以及适用范围,并且对多孔金属的应用进行了总结,主要从结构和功能两方面应用进行了分析,指出了其发展方向.     

Controlled local implementation of nonlocal operations

We propose a theoretical protocol for controlled local implementation of nonlocal operations first, and then give an alternative linear optical protocol to implement the task with a polarization analyzer. In this paper, with local operations, polarization measurement and classical communication, nonlocal operations can be locally implemented with the help of controllers.     

Image processing in remote sensing data analysis: The state of the art

Image analysis techniques applicable to remote sensing data are reviewed, with emphasis on recent developments. The topics covered include image modelling, feature detection, segmentation and classification, texture analysis, and matching.     

Deterministic generation of singlet state of N atoms in coupled cavities via adiabatic passage of a dark state

In this paper, we propose an efficient scheme to generate the N-atom singlet state via adiabatic passage of a dark state in cavity quantum electrodynamics (QED) system. Appropriate Rabi frequencies of the classical fields are selected to realize the present scheme. We discuss the influence of decoherence induced by cavity decay and atomic spontaneous emission by numerical calculation. The result shows that the scheme is insensitive to atomic spontaneous emission as the atomic excited state is hardly populated in adiabatic evolution.     

Preparation of tetragonal zirconia powders by a solid state reaction: Kinetics, phases and morphology

Powders of tetragonal (t)ZrO₂ have been prepared by a solid state reaction between sodium metazirconate and sodium metaphosphate. The reaction temperatures and times have been varied between 450 and 550°C and 5 and 75 h, respectively. Zirconia powder, mostly in thet andt′ phases, is obtained. The yield of ZrO₂ powder increases monotonically with time at all reaction temperatures according to a phase boundary controlled kinetics. The fraction oft phase also increases with time at 450°C and 500°C but goes through a maximum at 550°C, the highest temperature employed. A maximum of 55% of the precursor monoclinic zirconia (used to prepare sodium meta zirconate) is converted tot phase at 500°C/75 h. The ZrO₂ powder consists of crystallites of size 9–25 nm agglomerated into particles having average size between 2 and 4μm. The agglomerates have a breaking strength of 100 MPa. A hydrothermal treatment is found to break the agglomerates into smaller sizes. Grinding the powder in a mortar and pestle converts only 12% of thet phase into monoclinic, indicating that substantial fraction of the tetragonal phase is the non transformable varietyt′. Heating experiments also confirm this.     

纳米晶Ti(C,N)固溶体粉末的制备及组织结构研究

研究了纳米晶Ti(C,N)固溶体粉末的碳热还原反应制备及其组织结构特征。结果表明．以球形亚微米TiO2粉末和纳米碳黑为原料，通过原料成分C／Ti的准确配比和适当的工艺参数，可制备出成分优良的晶粒度为37nm的单相纳米晶Ti(C，N)固溶体粉末。     

固相反应法制备纳米铈锆复合氧化物

以碳酸铈、碳酸锆、草酸为原料,机械力促进固相反应法制备了纳米级铈锆复合氧化物(CexZr1-XO2)。用TGDSC分析前驱体的热分解温度,通过XRD、TEM、BET等测试手段对产物进行了表征。结果表明:所得产物为单一的立方晶系固溶体,平均粒径<40nm,比表面积达98m2/g。采用中低温固相反应法制备纳米级铈锆复合氧化物无需溶剂,无废液且节能。     

氟化石墨烯的制备研究进展

新型碳材料氟化石墨烯以独特的物理、化学性能受到广泛关注,在众多领域具有广阔的应用前景。综述了氟化石墨烯的制备方法,主要介绍以氟化石墨为原料的物理剥离法、使用不同溶剂作为插层剂的化学制备方法,以及以氧化石墨烯、石墨烯作为原料的制备方法,总结了各种制备方法的优缺点,并对未来氟化石墨烯的发展前景进行了展望。     

中空纤维微滤膜组件静态操作时过滤通量预测的实验研究

对中空纤维微滤膜组件在静态操作下处理酱油时过滤通量的预测进行了研究 .并从Ruth方程式出发 ,结合静态过滤的特点推导出了简单实用的过滤通量预测公式 .     

Foundations of content preparation for the web

The objective of this paper is to develop a model for content preparation of websites. Content preparation describes a process of web design that equally weighs the identification of information requirements with the presentation modes of that information. This paper focuses on what information should be available on the web instead of how the information should be presented. It reviews studies concerning: (a) credibility evaluation of printed media; (b) quality dimensions of information systems; (c) Internet domain-specific information needs. Based on the review, two key figures synthesise the aspects related to content preparation. First, the convergence hierarchy integrates domain-specific components into a general information structure. Second, the conceptual model proposed eight factors for effective content preparation. These factors are site, transaction, company, security, product, customer service, shipping and membership. It highlights specific content elements and yields major implications for a broad range of websites. Primarily, it establishes a foundation for developing methods to evaluate the effectiveness of content preparation for websites. Combining content preparation with usability methods will provide a comprehensive effectiveness evaluation of websites using the ISO 9241–11 (International Organization for Standardization, 1998. ISO 9241–11, Ergonomics requirements for office work with visual display terminals (VDTs)–Part 11 Guidance on usability. Geneva: ISO) framework. Also, it could act as a general guide of content preparation for websites.     

遥感影像在地外文明探索中发挥作用

六十年代以来,已向月球和水星、金星、火星、木星、土星、天王星,海王星等太阳系行星发去数十个空间遥感器,并已向地球上的地面站发回大量信息,使科学家们得以发现很多有趣的事物,显示为地球外生物高度文明的作为。本文着重介绍了在月球上发现的异常景物,显示可能在多年以前,曾有高度文明的生物在月球着陆。     

梯形聚苯基倍半硅氧烷的新型制备方法

以苯基三氯硅烷为原料,利用经过改良的热平衡缩合法,得到产物梯形聚苯基倍半硅氧烷(Ph-T)。借助傅立叶红外、X射线衍射和核磁共振硅谱等方法,确定了产物具有规整的梯形分子结构;以热重分析测定了其耐热性,在空气中失重5%时温度为530℃,具有优良的耐热性能。     

碳纳米管对中间相炭微球制备的影响

以中温煤沥青和碳纳米管为原料进行热缩聚反应,制备出含有碳纳米管的中间相炭微球,采用扫描电子显微镜(SEM)、激光粒度仪和X射线衍射(XRD)等分析手段对其形貌及结构进行了表征。研究了添加碳纳米管对中间相炭微球形貌、粒径、产率、微晶结构及热缩聚工艺的影响。结果表明添加碳纳米管能够促进小球成核,阻止小球的融并长大,使炭微球的粒径减小,分布均匀,但过多的碳纳米管会导致球形度变差及中间相沥青产率的降低;碳纳米管的存在使石墨片层尺寸减小,石墨化程度降低;碳纳米管经过酸煮处理后,可以获得球形度更好、含有更大比例碳纳米管的中间相炭微球。     

偏硅酸钙中Pr3+的4f5d态的光谱性质

高温下合成了掺Pr^3＋的CaSiO3,研究了Pr^3＋在室温下的发射光谱和激光谱,观测到Pr^3＋的4f5d态的两上能级,其最低能级向4f^2组态的^3H4,^3H6和^1G4发生辐射跃迁,其中以向^3H4的跃迁最强,而向^3Po和^1D2的无辐射跃迁几率可以忽略,从而得到了一种在短波紫外发光效率很高的新型材料。     

羟基磷灰石生物陶瓷材料的制备及其新进展

羟基磷灰石常用作医用生物陶瓷材料。本文对羟基磷灰石及其复合生物陶瓷材料的各种制备方法进行了概述和评论．重点介绍了羟基磷灰石制备方法的新进展．并对未来的发展前景进行了分析。     

有机磷农药残留前处理技术的研究

本实验主要是利用固相萃取技术对食品中有机磷农药前处理方法进行了研究。对自制的固相萃取小柱的选择参数进行了优化,建立合适的样品提取、净化、浓缩的前处理方法,确保色谱分析测定时无样品基质的干扰,从而为测定的结果提供了保证,并延长色谱柱的寿命,降低了实验成本。茶叶样品以丙酮为提取剂,超声波30 min后,经florisil柱(1000mg)+活性炭(50mg)混合柱浓缩净化,用10 mL的乙酸乙酯淋洗后,经色谱分析验证,所得回收率在73.7%以上,RSD在4.1%以下,结果令人满意。     

纳米BiVO4黄色颜料的制备研究

以Bi（NO3）3·2H2O和NaVO3为原料，采用液相沉淀法，制备BiVO4纳米材料。研究了反应温度和pH值对结果的影响。采用X射线衍射（XRD）、透射电子显微镜（TEM）和红外光谱（IR）技术对产物进行分析表征。结果表明，反应温度和pH值显著影响产物的结晶性和形貌结构，随着反应温度的逐步升高，产物的结晶性越来越好，而且物相趋向于单一的单斜晶系白钨矿结构。在相同的反应温度下，随着溶液pH的增大，产物由片状趋向干增厚的块状。     

聚乙烯醇复合膜的制备

以亲水性的聚乙烯醇为原料，采用机械涂敷法制备复合纳滤膜．考查了基膜、聚乙烯醇的浓度、交联剂的浓度及配比、涂层厚度、交联时间以及热处理等对膜分离性能的影响，确定了最终制备条件．在一定的温度和湿度条件下，在截留相对分子质量为100000的基膜上，通过5％的聚乙烯醇溶液与1％的戊二醛的交联反应，研制了截留相对分子质量为600的PVA复合纳滤膜。     

硝酸盐PAD法快速制备YBCO超导薄膜研究

用硝酸盐高分子辅助沉积法(简称PAD)来制备YB2C3O7-x(YBCO)超导薄膜,有着制备速度快、工艺简单和无环境污染等优点。采用硝酸盐水相前驱液,并加入高分子螯合剂和薄膜改性剂,然后将前驱液涂覆在LaAlO3(LAO)单基晶片上,采用快速低温分解,再经过高温烧结制备出完整的YBCO超导薄膜。在1.0×10-4 O2/N2气氛下制备的YBCO超导薄膜致密,YBCO(00l)峰取向明显,没有其它杂相峰,同时,转变起始温度TC=91K,转变宽度ΔTC=2K;在77K、自场下临界电流密度JC为约1MA/cm2。实验结果表明,采用硝酸盐PAD法的低温分解时间比传统的TFA-MOD法缩短9h左右,而且制备出的YBCO超导薄膜性能优良,该方法为以后的长带生产提供了一种新的制备技术。