冷原子系综内单集体激发态的相干操纵

原子系综内部分原子发生相干态转移后所处量子态被称为集体激发态.如果激发数目在单原子量级则被称为单激发态.在量子存储过程中,单光子以单激发态的形式在原子系综内进行存储.因此,研究单激发态的制备、演化、转化、干涉等过程是量子存储及其应用研究的关键.本文总结了近年来作者所在研究团队针对冷原子系综体系在此研究方向取得的若干成果.主要包括采用动量模式调控、三维光晶格等手段抑制单激发态的退相干,采用环形腔增强原子至光子的转化效率,发展基于拉曼光的单激发态相干转移技术,利用单量子态不同模式间干涉制备光与原子纠缠,利用里德伯阻塞机制提升纠缠制备效率等.此外,简要回顾了基于多个单激发态的量子中继及量子网络实验.     

Experimental Realization of Degenerate Fermi Gases of ~(87)Sr Atoms with 10 or Two Spin Components

We report the experimental realization of quantum degenerate Fermi gases of~(87)Sr atoms under controlled 10-and dual-nuclear-spin configurations.Based on laser cooling and evaporative cooling,we achieve an ultracold Fermi gas of 105 atoms equally distributed over 10 spin states,with a temperature of T/T_F = 0.21.We further prepare a dual-spin gas by optically pumping atoms to the mF = 9/2 and mF = 7/2 states and observe a slightly lower T/T_F than that for a 10-spin gas under the same trapping condition,showing efficient evaporative cooling under a decreasing number N of spin states(N≥2)despite the increasing importance of Pauli exclusion.Given that rethermalization becomes less efficient with N approaching unity,we evaporatively cool an almost polarized gas to 130 nK.The simple and efficient preparation of ultracold Fermi gases of ~(87)Sr with tunable spin configurations provides a first step towards engineering topological quantum systems.     

生理性病害对温室黄瓜栽培的影响

生理性病害对温室黄瓜栽培的影响平凉地区农科所王旭杰由于栽培和管理不当，近年来，温室黄瓜生理性病害在我区普遍发生，严重时发病率可达５０％以上。为此，我们进行了较系统的调查研究，并初步得出以下结论。１嫁接引起的生理性病害温室栽培中，绝大部分用黑籽南瓜做砧...     

晚播小麦的栽培管理技术

“早麦年年收，晚麦碰年头”。随着栽培技术的不断完善和生产水平的提高，这几年，晚麦和春小麦一样，都可获得好收成。好些地方产量和正常麦不相上下，就给生产上以启示，可以借鉴春小麦的增产经验，搞好晚麦栽培。试验观察表明，冬前幼苗只要有分蘖露出，在细小的分蘖节...