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量子逻辑网络的核磁共振实现 总被引:1,自引:1,他引:0
利用相位相反技术,设计出了实现精确的CN门的脉冲序列;构造了三量子位的双重控制相位旋转门(CCS门),它是将核磁共振(NMR)实现Grover量子算法从二量子位推广到三量子位的关键逻辑门,而且,依此方法,可以用NMR实现N量子位的Grover量子算法;还给出了量子Toffoli门以及量子态的各种对称操作的逻辑部件。所有这些逻辑操作都是构建量子态工程的工具。文中大部分脉冲序列己经在实验中得到验证,这些结果对于量子计算的理论研究和实验实现都具有现实意义。 相似文献
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加快天线残余能量释放以减弱天线振铃信号有利于缩短低场核磁共振仪器的回波间隔(TE),从而提高快弛豫组分的测量分辨率和信噪比(SNR).而天线Q值对能量的发射效率和泄放速度起着相反的作用.为此,我们首先设计了一种新型Q转换电路,在保证发射效率的同时,可以大大缩短能量泄放时间.在此基础上,应用了一种优化的脉冲序列以弥补传统相位交替对脉冲序列(PAPs)不能消除90°脉冲振铃的缺陷,通过相位循环的方法进一步提高了信噪比.最后,在2 MHz岩心分析仪上测试了新型Q转换电路,当天线Q值降为发射期间的约1/5时,天线恢复时间由280.0 μs降为18.2 μs;而且,使用新型Q转换电路和优化的脉冲序列后,TE=60 μs时,可以有效获得快弛豫组分的T2信号. 相似文献
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实验室仪器微机管理系统①刘奕新覃以威(百色师范专科学校百色533000)(广西师范大学桂林541001)1前言一个实验室仪器众多,种类繁杂。新购仪器的入库登记、分类造册、仪器的领用管理、现有仪器的使用情况、元件材料的库存情况等等,确实是令仪器管理人员... 相似文献
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有效实施新高考是普通高中面临的头等大事. 首先揭示新高考实施中面临的4大挑战;其次,提出应对
挑战的策略— — —新高考物理多元开放网络课程建设,并指出网络课程建设的重要作用;再次,揭示物理多元开放网
络课程的特点,并提出顶层设计;最后,结合具体教学实例就如何实施多元开放网络课程进行探索和实践 相似文献
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We present an efficient one-step scheme for a single spin measurement based on nuclear magnetic resonance (NMR) techniques. This scheme considerably reduces the time of operation using a spin star network where a target spin and an ancillary spin are coupled to a ring of N spins. As opposed to the proposal in [Phys. Rev. Lett. 97 (2006) 100501] using a cubic lattice crystal to achieve a cubic speedup, the distinct advantage of this scheme is that under ideal conditions it requires the application of only one step to create a system of N correlated spins. In the process of single spin measurement, the total macroscopic magnetization, the individual magnetization and the transfer fidelity are calculated analytically as simple cosine functions of time and the amplitude of irradiation. 相似文献
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介绍了一种应用于核磁共振(Nuclear Magnetic Resonance,NMR)波谱仪的宽频带射频功率放大器的设计与实现,提出了射频功率放大器门控信号的设计,探讨了利用传输线变压器构建功率MOSFET输入输出阻抗匹配网络的方法. 该射频功率放大器采用多级驱动结合功率放大的结构,包含2个工作模块和基于宽频带定向耦合器的辅助电路,支持高带和宽带通道的相关实验. 将该射频功率放大器应用在自主研发的500 MHz高分辨率液体NMR谱仪上,测量射频功放的上升、下降时间及输出线性度,并对比测试1H和13C NMR标样的信噪比,实验结果证明了该设计的可行性. 相似文献
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实验室开放与网络多媒体教学 总被引:4,自引:0,他引:4
开放物理实验教学能够激发学生学习的主动性和积极性,有利于培养学生的创新能力。本通过介绍开放实验教学的几种模式,说明实验室开放要与网络多媒体教学相结合,最后介绍了开放网络多媒体实验教学达到的效果。 相似文献
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本文是子课题 — — —“ 基于创新素养培育物理多元开放网络课程建设” 研究概要总结. 首先, 揭示传统创
新素养培育课程生态中存在问题, 提出“ 基于创新素养培育物理多元开放网络课程建设”研究问题; 其次, 根据拔尖
创新人才培养要求, 结合物理学科和互联网技术特点, 给出创新素养培育物理多元开放网络课程建设的顶层设计;
最后, 就基于创新素养培养物理多元开放网络课程实施策略进行探索 相似文献
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低磁场条件下天然气核磁共振特性的实验研究 总被引:13,自引:3,他引:10
研究天然气在低磁场条件下的核磁共振弛豫特性及含烃因子的变化对天然气的勘探和开发工作具有重要意义,由于受核磁共振仪器耐温、耐压条件的限制,这方面的研究工作非常少,国内还是空白. 本文在一套自行研制的耐高温、耐高压的低磁场(磁场强度0.056T )核磁共振设备上,对我国大庆油田深层天然气的核磁共振特性进行了实验研究,获得了天然气的T1弛豫时间、含烃因子随温度和压力变化的函数关系. 本文的研究内容对我国正在开展的核磁共振测井工作具有重要的参考价值. 相似文献
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We have reinvestigated a transmission line NMR probe first published by Lowe and co-workers in 1970s [Rev. Sci. Instrum. 45 (1974) 631; 48 (1977) 268] numerically and experimentally. The probe is expected to be ultra-broadband, thus might enable new types of solid-state NMR experiments. The NMR probe consists of a coil and capacitors which are connected to the coil at regular intervals. The circuit is the same as a cascaded LC low-pass filter, except there are nonzero mutual inductances between different coil sections. We evaluated the mutual inductances by Neumann's formula and calculated the electrical characteristics of the probe as a function of a carrier frequency. We found that they were almost the same as those of a cascaded LC low-pass filter, when the inductance L of a section was estimated from the inductance of the whole coil divided by the number of the sections, and if C was set to the capacitance in a section. For example, the characteristic impedance of a transmission line coil is given by Z=(L/C)(1/2). We also calculated the magnitude and the distribution of RF magnetic field inside the probe. The magnitude of RF field decreases when the carrier frequency is increased because the phase delay between neighboring sections is proportional to the carrier frequency. For cylindrical coils, the RF field is proportional to (pinu/2nu(d))(1/2)exp(-nu/nu(d)), where the decay frequency nu(d) is determined by the dimensions of the coil. The observed carrier frequency thus must be much smaller than the decay frequency. This condition restricts the size of transmission line coils. We made a cylindrical coil for a 1H NMR probe operating below 400 MHz. It had a diameter 2.3mm and a pitch 1.2mm. Five capacitors of 6pF were connected at every three turns. The RF field strength was 40 and 60 kHz at the input RF power 100 W by a calculation and by experiments, respectively. The calculations showed that the RF field inhomogeneity along the coil axis was caused by a standing wave of current, which arose from the reflections at the coil ends. The calculation showed that the homogeneity could be improved by decreasing the pitch near the both ends and making their impedance close to that at the center. 相似文献
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Dielectric losses in the patient may impair radiofrequency receiver coil sensitivity, and transmitter coil efficiency, in nuclear magnetic resonance (NMR) imagers. The frequency dependence of this loss mechanism is derived. Patient losses in a solenoidal head coil used for imaging heads were simulated by a cylindrical saline phantom. The frequency dependence of the loss introduced by the phantom can indicate whether dielectric losses in the patient will be significant compared to eddy current losses. The detuning caused by the phantom is used to calculate an upper limit for the distributed stray capacitance between coil and patient. Given the approximate conductivity of the patient, an upper limit for the dielectric loss can be estimated. Some methods of reducing patient dielectric losses are suggested. 相似文献
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IRMA/SXGX是一个综合性的实验室信息管理系统,它由实验室异种机网络、计算机辅助化学子系统和办公自动化管理子系统组成,该系统在UNIX或XENIX操作系统下的多用户分时微型机和DOS操作系统的微型机上运行。目前已有六种分析仪器的计算机和五台中西文终端以及两台打印机联入该系统,能自动传输和管理实验室信息。这种多功能的信息管理系统有助于扩大分析测试服务领域,提高工作效率,改善分析结果的准确性。本文对该系统的设计策略、硬件配置、软件运行环境和系统功能作了介绍。 相似文献