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1.
Retraction: Optical pumping nuclear magnetic resonance system rotating in a plane parallel to the quantization axis 下载免费PDF全文
Requested by the authors,the article entitled “Optical pumping nuclear magnetic resonance system rotating in a plane parallel to the quantization axis”,published in Chinese Physics B,2017,Vol.26,Issue 9,Article No.093301,has been withdrawn from the publication.The authors found that the axes in the rotating frame xy'z are not all time-invariant,so Eq.(12) obtained from Eq.(11) is incorrect,and the conclusion is inaccurate. 相似文献
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The sensitivity of one-dimensional dynamic magic-angle spinning (MAS) and off-MAS 2H nuclear magnetic resonance spectra to changes in the parameters of jump-type molecular motions is studied. The Floquet theory approach is used to simulate spectra of spins with I = 1, which are involved in exchange processes in rotating solids. The solution of the Bloch-McConnell equations for rotating samples are derived and some simulated frequency spectra are shown. The dependence of the lineshapes of the center and sidebands of the MAS and off-MAS spectra on the exchange parameters are discussed. Experimental results of 2H spectra of perdeuterated dimethyl sulfone, obtained in the temperature range 20–55 °C, are demonstrated. The methyl groups in this molecule undergo π flips at rates that can be detected by MAS and off-MAS NMR. The shapes of the experimental sidebands are compared with simulated results. 相似文献
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Parameter analysis for a nuclear magnetic resonance gyroscope based on bf133Cs-129Xe/131Xe 下载免费PDF全文
We theoretically investigate several parameters for the nuclear magnetic resonance gyroscope based on 133Cs-129Xe/131Xe. For a cell containing a mixture of 133Cs at saturated pressure, we investigate the optimal quenching gas (N2) pressure and the corresponding pump laser intensity to achieve 30% 133Cs polarization at the center of the cell when the static magnetic field B0 is 5 μT with different 129Xe/131Xe pressure. The effective field produced by spin-exchange polarized 129Xe or 131Xe sensed by 133Cs can also be discussed in different 129Xe/131Xe pressure conditions. Furthermore, the relationship between the detected signal and the probe laser frequency is researched. We obtain the optimum probe laser detuning from the D2 (62S1/2→62P3/2) resonance with different 129Xe/131Xe pressure owing to the pressure broadening. 相似文献
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We propose and realize a new optical state selection method on a cesium atomic fountain clock by applying a two-laser 3-3' optical pumping configuration to spin polarize atoms. The atoms are prepared in |F=3, mF=0> clock state with optical pumping directly after being launched up, followed by a pushing beam to push away the atoms remaining in the |F=4> state. With a state selection efficiency exceeding 92%, this optical method can substitute the traditional microwave state selection, and helps to develop a more compact physical package. A Ramsey fringe has been achieved with this optical state selection method, and a contrast of 90% is obtained with a full width half maximum of 0.92 Hz. The short-term frequency stability of 6.8×10-14 (τ/s)-1/2 is acquired. In addition, the number of detected atoms is increased by a factor of 1.7 with the optical state selection. 相似文献
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Jianwei Zhou Liyun Li Hongbing Hu Baolian Yang Zhaohong Dan Jianqing Qiu Jiugao Guo Feng Chen Chaohui Ye 《Solid state nuclear magnetic resonance》1994,3(6):339-351
The results of a study of two types of natural-diamond crystals by dynamic nuclear polarization (DNP)-enhanced high-resolution solid-state 13C nuclear magnetic resonance (NMR) are reported. The home-built DNP magic-angle spinning (MAS) 13C NMR spectrometer operates at 54 GHz for electrons and 20.2 MHz for carbons. The power of the microwave source was about 30 W and the highest DNP enhancement factor came near to 103. It was shown that in the MAS spectra the 13C NMR linewidths of the Ib-type diamond were broader than those of IaB3-type diamond. From the hyperfine structure of the DNP enhancement as a function of frequency, four kinds of nitrogen-centred and one kind of carbon-centred free radicals could be identified in the Ib-type diamond. The hyperfine structures of the DNP enhancement curve that originated from the anisotropic hyperfine interaction between electron and nuclei could be partially averaged out by MAS. The 13C polarization time of DNP was rather long, i.e. 1500 s, and the spin—lattice relaxation time (without microwave irradiation) was about 300 s, which was somewhat shorter than anticipated. Discussions on these experimental results have been made in this report. 相似文献
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电阻式核磁共振(RDNMR)测量是1988年由德国马普所的von Klitzing研究小组针对GaAs二维电子气中少量核自旋的探测而提出的一种具有超高灵敏度的实验技术. 目前, RDNMR已经成为研究单层或双层GaAs二维电子气核自旋和电子自旋特性的重要手段. 由于为实现电阻式核磁共振测量所建立的动态核极化方法强烈依赖于GaAs特有的材料属性, 至今这一技术一直没有扩展应用到其他半导体低维系统中. 最近,本研究小组发展了一种动态核极化新方法,成功实现了对典型窄带半导体锑化铟(InSb) 二维电子气的电阻式核磁共振测量.本文在介绍电阻式核磁共振测量工作原理及已建立的典型动态核极化方法的基础上,着重讨论所提出的动态核极化新方法的机理、 实验结果以及对今后研究的展望. 相似文献
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Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot(QD) by the coherent population trapping(CPT) and the electric dipole spin resonance(EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip–flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time. 相似文献
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The newly discovered iron-based superconductors have triggered renewed enormous research interest in the condensed matter physics community. Nuclear magnetic resonance (NMR) is a low-energy local probe for studying strongly correlated electrons, and particularly important for high-Tc superconductors. In this paper, we review NMR studies on the structural transition, antiferromagnetic order, spin fluctuations, and superconducting properties of several iron-based high-Tc superconductors, including LaFeAsOl_xFx, LaFeAsOl_x, BaFe2As2, Bal_xKxFe2As2, Cao.23Nao.67Fe2As2, BaFe2(Asl_xPx)2, Ba(Fel_xRux)2As2, Ba(Fel_xCox)2As2, Lil+xFeAs, LiFel_xCoxAs, NaFeAs, NaFel_xCoxAs, KyFe2_xSe2, and (T1,Rb)yFe2_xSe2. 相似文献
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Optical pumping and population transfer of nuclear-spin states of caesium atoms in high magnetic fields 下载免费PDF全文
Nuclear-spin states of gaseous-state Cs atoms in the ground state
are optically manipulated using a Ti:sapphire laser in a magnetic
field of 1.516T, in which optical coupling of the nuclear-spin
states is achieved through hyperfine interactions between electrons
and nuclei. The steady-state population distribution in the
hyperfine Zeeman sublevels of the ground state is detected by using
a tunable diode laser. Furthermore, the state population transfer
among the hyperfine Zeeman sublevels, which results from the
collision-induced modification \delta a(\bm S \cdot \bm I) of the
hyperfine interaction of Cs in the ground state due to stochastic
collisions between Cs atoms and buffer-gas molecules, is studied at
different buffer-gas pressures. The experimental results show that
high-field optical pumping and the small change \delta a(\bm S
\cdot \bm I) of the hyperfine interaction can strongly cause the
state population transfer and spin-state interchange among the
hyperfine Zeeman sublevels. The calculated results maybe explain the
steady-state population in hyperfine Zeeman sublevels in terms of
rates of optical-pumping, electron-spin flip, nuclear spin flip, and
electron-nuclear spin flip-flop transitions among the hyperfine
Zeeman sublevels of the ground state of Cs atoms. This method may be
applied to the nuclear-spin-based solid-state quantum computation. 相似文献
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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. 相似文献
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在连续波核磁共振实验中,通常采用低频扫场产生重复再现的共振吸收信号。当处于磁场中的射频线圈引线回路等效面积不为零时,简谐扫场必然引起该闭合回路的磁通量变化,由此而产生同频简谐感生电动势并与核磁共振信号叠加共同构成振荡器输出信号。由于扫场上升和下降过程的感生电动势方向相反,从而扫场前半周和后半周所对应的共振吸收测量信号存在差异。实验结果表明:扫场强度及方向对核磁共振测量影响来源于实验测量技术缺陷,而非核磁共振的物理本质。 相似文献
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We have developed the nuclear spin maser oscillating at a low frequency of 34 Hz with highly polarized nuclear spins of the
noble gas element 129Xe. The system is advantageous for detecting a small frequency shift of the nuclear spin precession. We are thus planning
to apply this system to the search for an atomic electric dipole moment of 129Xe. We here report the development of the system and its performance. 相似文献
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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. 相似文献
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近年来, 随着量子信息科学的发展, 对由量子力学原理描述的微观世界的主动调控已成为重要的前沿研究领域. 为构造实际的量子信息处理器, 一个关键的挑战是: 如何对处于噪声环境下的量子体系实现一系列高精度的任意操作, 以完成目标量子信息处理任务. 为此, 人们将经典系统控制论的思想方法延伸到量子体系的领域, 提出了大量的量子控制方法以及相关的数值技术(如量子优化控制、量子反馈控制等), 并取得了丰富的研究成果. 核磁共振自旋体系具备成熟的系统理论和操控技术, 为量子控制方法的实用性研究提供了优秀的实验测试平台. 因此, 基于核磁共振的量子控制成为量子控制领域的重要方向. 本文简要介绍了量子控制的基本概念和方法; 从系统控制论的角度对核磁共振自旋体系的基本原理和重要控制任务做了阐述; 介绍了近些年来在该领域发展的相关控制方法及其应用; 对基于核磁共振体系的量子控制的进一步的研究做了几点展望. 相似文献
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文章介绍了利用核磁共振法对铁基高温超导体的研究结果.笔者研究组断定铁基超导是自旋单态配对,并首先发现超导多能隙的存在.正常态的反铁磁自旋涨落在自旋空间是各向异性的,它与超导的关系,是人们关心的热点之一. 相似文献