Experimental realization of information transmission between not-directly-coupled spins on NMR quantum computers

This paper presents a simple scheme for information transmission between two non-directly interactive qubits in an n-qubit system. An example has been realized on a three-qubit nuclear magnetic resonance (NMR) spectrometer quantum computer. The experimental result successfully demonstrates that the feasible measure can also be extended to other quantum logical gates, or other quantum algorithms, where some qubits have no direct interactions in a multi-qubit system.     

低场流动系统中超极化129Xe气体辐射阻尼的研究

辐射阻尼现象通常只有在高磁场中,利用高分辨率谱仪,才能观测到液态,像水质子这样具有大自旋浓度的信号.但是我们在低场流动系统中,利用光泵自旋交换的方法,获得高度极化的129Xe气体,从而使我们能观测到,流动系统下超极化129Xe的气态辐射阻尼信号.     

Production of Hyperpolarized 129^Xe Gas Without Nitrogen by Optical Pumping at 133^Cs D2 Line in Flow System

We report production of hyperpolarized 129^Xe gas via spin-exchange with optically pumped Cs atoms at the D2 line, achieved at low magnetic field in a flow system and in the absence of nitrogen gas. The nuclear spin polarization of hyperpolarized 129^Xe gas is enhanced by a factor of 10000 compared to that without optical pumping under the same condition, which corresponds to polarization of about 2.66%. Due to the high spin polarization, the radiation damping of hyperpolarized 129^Xe gas has also been observed in the flow system.     

空间量子密码通信

量子密码术是一门崛起的新兴技术，其传输的安全性基于量子力学的Heisenberg不确定原理。而其中空间量子密码通信以其近期迅猛的发展和广阔的前景备受瞩目。本文从量子密码术的基本原理出发，综合叙述了空间量子密码通信的发展和最新成果。     

新的summing算法的核磁共振实验实现

本文报导了一种新的summing算法的核磁共振实验实现.实验中我们用到了四个量子位的核自旋体系,其中两个量子位构成输入寄存器,另两个量子位构成输出寄存器.最后的实验结果只需通过测量输出寄存器中核自旋的谱线获得.     

MEASUREMENTS OF RELAXATION OF SPIN POLARIZED 129Xe NUCLEI IN HIGH MAGNETIC FIELDS

We observed the NMR signal of low-pressure gas ¹²⁹Xe by laser enhanced method on an MSL-400 NMR spectrometer and measured nuclear spin relaxations of ¹²⁹Xe gas at various temperatures. The relaxation rate constant of ¹²⁹Xe-¹³³Cs spin exchange was obtained as (6.8±0.5)×10^-16cm^-3s^-1.     

MEASUREMENTS OF 129Xe NUCLEAR MAGNETIC RESONANCE IN GASEOUS, LIQUID AND SOLID XENON

Natural xenon, contained in a ceil at a pressure of 6.5 atm, is frozen from 303 to 137 K on an WP-80SY NMR spectrometer. NMR signals of ¹²⁹Xe atoms in gaseous, liquid and solid phases are measured at various temperatures, We found that the chemical shift of NMR signal of liquid ¹²⁹Xe (expressed as ΔH) is directly proportional to the density of the sample with a coefficient of (4.73±0.05)×10^-7; and the chemical shift of NMR signal of solid ¹²⁹Xe (expressed as ΔH) is nearly proportional to the density of the sample with a coefficient of (5.00±0.08)×10^-7.     

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...     

THE 82S1/2→62D EXCITATION TRANSFER OF RUBIDIUM ATOMS INDUCED BY COLLISIONS WITH GROUND-STATE RUBIDIUM AND HYDROGEN MOLECULES

The processes of excitation transfer from the 8²S_1/2 state to the 6²D state of rubidium in Rb(8²S_1/2)-Rb(5²S_1/2) and Rb(8²S_1/2)-H₂ collisions have been studied experimentally. During irradiating the Rb vapor, mixed with H₂, by two light beams for selective stepwise excitation, the Rb 8²S_1/2→5²P_3/2 direct fluorescence and the Rb 6²D_3/2→5²P_1/2 sensitized fluorescence have been measured as a function of H₂ gas pressure. The measurements yielded the cross-sections σ(8²S_1/2→6²D) and σ^*(8²S_1/2→6²D) of Rb 8²S_1/2→6²D excitation tranfer induced by collisions with 5²S_1/2 atom and H₂ molecules respectively. The results are discussed in detail.     

MEASUREMENTS OF 129Xe NUCLEAR MAGNETIC RESONANCE IN GASEOUS,LIQUID AND SOLID XENON

Natural xenon, contained in a ceil at a pressure of 6.5 atm, is frozen from 303 to 137 K on an WP-80SY NMR spectrometer. NMR signals of ¹²⁹Xe atoms in gaseous, liquid and solid phases are measured at various temperatures, We found that the chemical shift of NMR signal of liquid ¹²⁹Xe (expressed as ΔH) is directly proportional to the density of the sample with a coefficient of (4.73±0.05)×10^-7; and the chemical shift of NMR signal of solid ¹²⁹Xe (expressed as ΔH) is nearly proportional to the density of the sample with a coefficient of (5.00±0.08)×10^-7.