核磁共振成像一维空间编码教学实验

利用梯度磁场实现检测信号的空间编码,是核磁共振成像(MRI)的关键技术.本文采用ccc系列样品将二维问题简化为一维,使用超小型教学用核磁共振成像仪进行了一维空间编码实验研究,并对实验过程及实验结果进行了计算模拟和分析.     

连续波核磁共振吸收的频域测量

目前连续波和脉冲核磁共振实验教学普遍侧重于时域观测.针对该问题,在原有主体设备环境中,配合通用仪器实施核磁共振吸收的频域测量.由稳压源输出提供变容二极管偏压而调节振荡频率,利用交流信号源简谐励磁电流调制磁场,采用锁相放大技术实现核磁共振吸收频域微分测量.实验结果直观准确地显示了同一物质在相同实验环境中核磁共振吸收的时域和频域特性.本工作不仅拓展了实验教学内容并加深对实验技术的理解,也为不同对象的个性化学习需要提供层次化教学环境.     

自主研制核磁共振波谱仪的性能评估

主要介绍自主研制500 MHz核磁共振谱仪的性能评估情况,旨在建立一台功能完整的核磁共振波谱仪. 首先利用系统调试使控制台各个硬件单元在用户软件控制下实现NMR实验中的基本功能,然后通过性能测试保障功率线性度、信号稳定性和场频联锁的可靠性,实验验证了谱仪溶剂峰压制的效果,并获得良好的探头线形指标（0.43/5.46/10.73 Hz）和¹H灵敏度指标（信噪比为728∶1）,表明自主研制500 MHz核磁共振波谱仪系统能够满足常规核磁共振实验需求.     

自制微成像系统的Spiral快速成像实现

自制了一种核磁共振微成像系统,本系统只需4根通用的I/O并行口线,就可以利用常规的NMR谱仪进行核磁共振微成像实验. 文中给出了相关的控制软件、螺旋（Spiral）快速成像相关软件以及实现过程,最后给出实验结果.     

多量子比特核磁共振体系的实验操控技术

随着量子信息与量子计算科学的发展,量子信息处理器被广泛地用于量子计算、量子模拟、量子度量等方面的研究.为了能在实验上实现这些日益复杂的方案,将量子计算机的潜能转化成现实,需要不断提高可操控的量子体系比特位数,实现更复杂的量子操控.核磁共振自旋体系作为一个优秀的量子实验测试平台,提供了丰富而又精密的量子操控手段.近几年来在此平台上进行了不少的多量子比特实验,发展并积累了一系列的多量子比特实验技术.本文首先阐述了核磁共振体系多量子比特实验中的实验困难,然后结合7量子比特标记赝纯态制备以及其他有关实验,对多比特实验过程中应用到的实验技术进行介绍.最后对核磁共振体系多量子比特实验技术方向的进一步研究进行了总结和展望.     

固体核磁共振样品制备系统的自主研制

近年来,国内多个科研单位引进了固体核磁共振波谱仪．由于目前固体核磁共振波谱仪还没有国产化,完全依赖进口,因此仪器及配套的样品制备系统价格昂贵．转子是魔角旋转核磁共振实验的关键耗材,其尺寸精密度要求极高,加工难度大．通过分析进口成品3.2 mm固体核磁共振转子及其配套样品制备工具的特性和实际应用需求,改进转子各零部件之间的连接方式,优化转子的密封性,成功实现了固体核磁共振转子和配套样品制备工具箱的自主研制．测试结果表明,自主研制的转子能在12 kHz转速下正常运行,满足常规固体核磁共振实验需求,且配套的样品制备工具箱操作简单,安全可靠．     

核磁共振实现基本量子逻辑门和量子分立付里叶变换

本文详细研究了利用核磁共振方法实现基本量子逻辑操作,提出了实现量子分立付里叶变换的实验方案,设计了可供实验的脉冲系列,为实验研究量子分立付里叶变换提供了具体方案。     

自旋回波的简易观测方法及共振弛豫分析

在脉冲核磁共振实验中,通常采用自旋回波法测量共振弛豫时间,但模拟示波器观测难以获得准确的实验数据.通过对计算机标准配置资源声卡的性能检测及标定,使其达到物理实验测量数据定量分析的教学要求,同时利用免费的简易程序实现多通道数字信号采集功能并用于观测记录脉冲核磁共振信号.配合实验操作技术改进,既准确地测量了横向弛豫时间,又展现了符合物理实验教学的计算机应用方法.     

一体化核磁共振谱仪数据交换的实现机制

核磁共振（NMR）随着其应用领域的拓展和深入,核磁共振谱仪技术得到了不断的发展和完善^[1,2]_. 针对以往谱仪存在的一些问题,本文提出了一种一体化核磁共振谱仪数据交换的实现机制,同时提出了基于ARM（Advanced RISC Machines,先进精简指令计算机）微处理器的嵌入式操作系统软件设计方案,并给出了谱仪各功能模块的实际性能测试结果,对实验结果进行了总结和讨论.      

开设核磁共振实验的探讨

针对目前高校理科物理专业近代物理实验中核磁共振实验开放现状的不足之处，提出了在核磁共振基本实验中增加脉冲核磁共振实验内容的设想，并在分析了该设想可行性的基础上设计了实验方案。     

Nuclear magnetic resonance for quantum computing: Techniques and recent achievements

Rapid developments in quantum information processing have been made, and remarkable achievements have been obtained in recent years, both in theory and experiments. Coherent control of nuclear spin dynamics is a powerful tool for the experimental implementation of quantum schemes in liquid and solid nuclear magnetic resonance(NMR) system,especially in liquid-state NMR. Compared with other quantum information processing systems, the NMR platform has the advantages such as the long coherence time, the precise manipulation, and well-developed quantum control techniques,which make it possible to accurately control a quantum system with up to 12-qubits. Extensive applications of liquid-state NMR spectroscopy in quantum information processing such as quantum communication, quantum computing, and quantum simulation have been thoroughly studied over half a century. This article introduces the general principles of NMR quantum information processing, and reviews the new-developed techniques. The review will also include the recent achievements of the experimental realization of quantum algorithms for machine learning, quantum simulations for high energy physics, and topological order in NMR. We also discuss the limitation and prospect of liquid-state NMR spectroscopy and the solid-state NMR systems as quantum computing in the article.     

Nuclear magnetic resonance: A quantum technology for computation and spectroscopy

In this article we consider nuclear magnetic resonance (NMR) as an example of a quantum technology; we consider in particular detail the implementation of quantum computers using NMR. We begin by outlining the physical principles underlying NMR, and give an introduction to the quantum mechanics involved. We next discuss the general characteristics of quantum technologies and the ways and extent to which these characteristics are expressed in NMR. We then give an introduction to the subject of quantum computation and its implementation using NMR. Finally, we describe some spectroscopy techniques which also exploit the quantum nature of NMR.     

核磁共振量子信息处理研究的新进展

过去的二十年中,量子信息相关研究取得了显著的进展,重要的理论和实验工作不断涌现.与其他量子信息处理系统相比,基于自旋动力学的核磁共振系统,不仅具有丰富而且成熟的控制技术,还拥有相干时间长、脉冲操控精确、保真度高等优点.这也是核磁共振体量子系统能够精确操控多达12比特的量子系统的原因.因此,核磁共振量子处理器在量子信息领域一直扮演着重要角色.本文介绍核磁共振量子计算的基本原理和一些新研究进展.研究的新进展主要包括量子噪声注入技术、量子机器学习在核磁共振平台上的实验演示、高能物理和拓扑序的量子模拟以及核磁共振量子云平台等.最后讨论了液态核磁共振的发展前景和发展瓶颈,并对未来发展方向提出展望.     

Quantum Logic Gates and Nuclear Magnetic Resonance Pulse Sequences

There has recently been considerable interest in the use of nuclear magnetic resonance (NMR) as a technology for the implementation of small quantum computers. These computers operate by the laws of quantum mechanics, rather than classical mechanics and can be used to implement new quantum algorithms. Here we describe how NMR in principle can be used to implement all the elements required to build quantum computers, and draw comparisons between the pulse sequences involved and those of more conventional NMR experiments.     

Quantum simulations with nuclear magnetic resonance system

Thanks to the quantum simulation,more and more problems in quantum mechanics which were previously inaccessible are now open to us.Capitalizing on the state-of-the-art techniques on quantum coherent control developed in past few decades,e.g.,the high-precision quantum gate manipulating,the time-reversal harnessing,the high-fidelity state preparation and tomography,the nuclear magnetic resonance(NMR) system offers a unique platform for quantum simulation of many-body physics and high-energy physics.Here,we review the recent experimental progress and discuss the prospects for quantum simulation realized on NMR systems.     

七量子位Deutsch-Josza量子算法的核磁共振实验实现

近年来 ,量子计算机的研究有了很大的发展 ,在目前提出的各种量子计算的方案中 ,核磁共振技术对模拟和演示量子算法以及验证量子计算机的优越性做出了巨大的贡献 .Deutsch Jozsa算法是一种研究较为广泛的量子算法 ,它可以用核磁共振实验予以验证 ,并可根据Cirac等人提出的方案予以简化 .报道了在核磁共振量子计算机上实验实现七位Deutsch Jozsa算法的过程和结果. Recent years, remarkable progresses in experimental realization of quantum information have been made, especially based on nuclear magnetic resonance (NMR) theory. In all quantum algorithms, Deutsch-Jozsa algorithm has been widely studied. It can be realized on NMR quantum computer and also can be simplified by using the Cirac s scheme. In this paper, at first the principle of Deutsch-Jozsa quantum algorithm is analyzed, then we implement the seven-qubit Deutsch-Jozsa algorithm...     

清华物理系量子信息研究的新进展

在清华大学物理系成立60周年之际,我们对近年来清华大学物理系量子信息研究的主要进展情况作一介绍,包括量子搜索算法研究,核磁共振量子计算的实验研究,量子通讯的理论与实验研究.在量子搜索算法研究方面,我们提出了量子搜索算法的相位匹配,纠正了当时的一种错误观点,并且提出了一种成功率为100%的量子搜索算法,改进了Grover算法;在核磁共振量子计算实验方面,我们实现了2到7个量子比特的多种量子算法的实验演示;在量子通讯方面,我们提出了分布式传输的量子通讯的思想,应用于量子密钥分配、量子秘密共享、量子直接安全通讯等方面,构造了多个量子通讯的理论方案.在实验室,我们实现了2米距离的空间量子密码通讯的演示实验.     

Ising耦合体系中量子傅里叶变换的优化

量子傅里叶变换是量子计算中一种重要的量子逻辑门. 任意量子位的傅里叶变换可以分解为一系列普适的单比特量子逻辑门和两比特量子逻辑门, 这种分解方式使得傅里叶变换的实验实现简单直观, 但所用的实验时间显然不是最短的. 本文利用优化控制和数值计算方法对Ising耦合体系中多量子位傅里叶变换的实验时间进行优化, 优化后的实现方法明显短于传统方法. 优化方法的核磁共振实验实现验证了其有效性.     

Implementation of the quantum Fourier transform

A quantum Fourier transform (QFT) has been implemented on a three qubit nuclear magnetic resonance (NMR) quantum computer to extract the periodicity of an input state. Implementation of a QFT provides a first step towards the realization of Shor's factoring and other quantum algorithms. The experimental implementation of the QFT on a periodic state is presented along with a quantitative measure of its efficiency measured through state tomography. Experimentally realizing the QFT is a clear demonstration of the ability of NMR to control quantum systems.     

Concepts of spin quantum computing

Quantum computing is based on two-state quantum systems called qubits. Recent proposals for quantum computing included nuclear spin 1/2 as qubits and implementations of several quantum algorithms were demonstrated by applying liquid-state NMR. Here I want to lay out some of the concepts of spin quantum computing including nuclear and electron spins. This article is intended to serve a dual purpose. It should on one hand introduce the reader who is not familiar with magnetic resonance to the spin quantum computing terminology and the concepts of pulsed magnetic resonance. At the same time I want to introduce the NMR expert to the recent developments in quantum computing.