Ultranarrow absorptive spectral line induced by microwave field

This paper investigates the absorptive spectral lines of four-level atomic system driven by a coupling, probe and microwave fields. Due to the perturbation of the microwave field, the original electromagnetically induced transparency is changed to electromagnetically induced absorption and the absorptive spectral line can be very narrow. This ultranarrow spectral line has potential applications to the microwave atomic frequency standard and the measurement of very weak magnetic field.     

Optical bistability via amplitude and phase control of a microwave field

We investigate the steady-state optical bistability behavior in a three-level Λ-type atomic system closed by a microwave field under the condition that the applied fields are in resonance with corresponding atomic transitions. It is shown that the bistable hysteresis cycles can be controlled by both the amplitude and the phase of the microwave field.     

微波场作用下三能级原子系统的无反转光放大

研究了外加微波场作用下三能级原子系统的无粒子数反转放大特性. 通过求解系统的密度矩阵方程得到其探测吸收谱. 结果表明, 介质对探测场的吸收呈现多峰结构, 并且在强微波驱动场的作用下, 特定范围内出现了明显的负吸收(即光放大). 进一步定量分析各能级粒子数布居随作用场强度的变化, 揭示出该三能级原子系统呈现无粒子数反转光放大的规律. 最后, 采用缀饰态理论对探测吸收特性做出了准确的解释.     

Field and dipole squeezing in a driven degenerate Λ quantum-beat system

The properties of field squeezing and atomic dipole squeezing in a coherent-microwave field driven degenerate Λ quantum-beat system were theoretically investigated. Numerical calculations indicate that the driving microwave may enhance or suppress both dipole squeezing and cavity-field squeezing, depending on the atomic energy level splitting and the microwave Rabi frequency.     

微波射频场调制下Λ型三能级原子系统的电磁感应光栅

研究了在微波射频场调制下的Λ 型三能级原子系统的电磁感应光栅现象. 结果表明: 微波场可以增强对探测场的相位调制和增益作用, 使得衍射强度、尤其是一阶衍射强度明显提高; 当系统参数取值适当时, 一阶衍射强度随微波场强度呈指数增长的趋势. 关键词： 电磁感应光栅 电磁感应透明 微波射频场     

Coherent Coupling between Microwave and Optical Fields via Cold Atoms

We demonstrate a long-coherent-time coupling between microwave and optical fields through cold atomic ensembles.The phase information of the microwave field is stored in a coherent superposition state of a cold atomic ensemble and is then read out by two optical fields after 12 ms.A similar operation of mapping the phase of optical fields into a cold atomic ensemble and then retrieving by microwave is also demonstrated.These studies demonstrate that long-coherent-time cold atomic ensembles could resonantly couple with microwave and optical fields simultaneously,which paves the way for realizing high-efficiency,high-bandwidth,and noiseless atomic q uant um converters.     

Enhancement of nonlinear susceptibility in a four-level tripod scheme

We propose a scheme for the enhancement of nonlinear susceptibility in a four-level tripod-type atomic system in the presence of a microwave field. With a microwave field, nonlinear susceptibility can be enhanced. Nonlinearity can also be ulteriorly enhanced by controlling the coupling field under the optimal intensity of the microwave field. The physical mechanism of the obtained giant nonlinear susceptibility is mainly based on interactions between microwave field and coupling fields. We present a physical understanding of our numerical results using a dressed-state approach and an analytical explanation.     

主动型氢原子钟原子弛豫时间的测量和分析

氢原子钟的原子弛豫时间是原子系统经过选态去除基态超精细能级（F = 0,m_F = 0）态和（F = 1,m_F = −1）态原子后,部分氢原子从（F = 1,m_F = 0）态跃迁至（F = 0,m_F = 0）态直至原子系统达到平衡状态所需的时间,该参数反映了原子的寿命,并直接影响氢原子钟的稳定度指标.为了测量主动型氢原子钟的弛豫时间,进而评估其性能,通过Raspberry Pi（RPI）产生时序信号,控制数字衰减器和电离源供电电路的继电器,从而控制微波探测信号的开启和原子束流的通断,并与数据采集等电路组成了氢原子自由感应衰减测试系统.通过对采集的自由感应衰减信号建模拟合,测算了氢原子钟的弛豫时间.该方法对于评估和优化原子线宽,改进主动型氢原子钟稳定度指标具有重要的参考意义.     

Optical bistability using quantum coherence in a microwave-driven four-level atomic system

The behavior of the optical bistability (OB) is investigated in an optical system which consists of a four-level atomic system with a microwave drive field and an optical cavity. It is found that the optical bistability can be accomplished by adjusting different physical parameters in both steady and transient process. Due to the existence of the microwave drive field, the optical bistability can be also obtained even under weak coherent coupling field condition. Since the intensity and phase of microwave drive field can be conveniently modulated, this optical system provides a new experimental method to test the optical bistability theory.     

五能级87Rb原子系统中相干诱导的可调谐三光子带隙

研究了一个由两个同向驻波场和一个微波场相干驱动的五能级87 Rb原子系统,并在探测场共振频率处实现了可调谐三光子带隙。利用激光场与多能级原子系综相互作用的密度矩阵方程,结合光脉冲在具有空间周期性介质中的相干传输矩阵理论,推导出了描述相干原子系统稳态条件下的反射谱和透射谱。由数值模拟发现,通过改变驱动场的失谐和拉比频率可以动力学地调控光子带隙的位置和宽度,而且这种相干诱导三光子带隙能够同时操控三个不同中心频率光脉冲的传播。     

微波消解-火焰原子吸收光谱法测定环境土壤中的总铬

应用微波消解-火焰原子吸收光谱法测定环境土壤中总铬的含量.土壤样品经HNO3+HzO2微波消解体系消解后,采用氯化铵作为基体改进剂,用原子吸收分光光度计在波长357.9nm,富燃烧性(还原性)火焰中测定土壤中的铬.铬含量在0-2.00mg/L范围与吸光度呈良好的线性关系,线性相关系数r=0.9993,最低检出限为5.0...     

Synchronization of Raman transitions in highly excited hydrogen atoms: A new proposal for measuring the Rydberg constant

We present an analysis of the Raman interaction between a Rydberg atom and ultrashort light pulses. An application of the synchronization of quantum transitions to a simple atomic system (the hydrogen atom) is demonstrated. This is a direct way of measuring times and frequencies of microwave transitions between the high-lying atomic states using ultrashort light pulses. The results and analysis represent a new method for measuring the Rydberg constant.     

Slow-light solitons in three-level atomic systems modified by a microwave field

We study the modified effect of slow-light soliton in a resonant three-level atomic system via electromagnetically inducedtransparency (EIT) by utilizing a microwave field. We derive ahigh-order nonlinear Schrödinger equation by using a perturbation method of multiple-scales, and calculate the modification ofsoliton velocity and frequency shift. We find that in the presence of the microwave field an obvious decrease of propagating velocityof soliton can be realized, which provides an effective method to slow down optical solitons in EIT systems. We also find that thedown shift of oscillating frequency of soliton in such system can be largely suppressed by the microwave field.     

铷原子频标鉴频信号信噪比相关问题分析

频率稳定度是铷原子频标最重要的性能指标. 铷频标频率稳定度主要由原子鉴频信号的信噪比决定. 本文分析了微波腔的结构、铷光谱灯的光谱纯度和同位素滤光方案对信噪比的影响,指出采用模式优越、微波填充因子大的微波腔,光谱纯度高的铷光谱灯,用分离滤光方法进行同位素滤光,可以提高铷原子鉴频信号的信噪比,从而使铷频标的稳定度指标得到进一步改善.      

空心阴极灯激发的微波等离子体炬原子/离子荧光光谱研究--钙的原子/离子荧光光谱

用强短脉冲供电技术的空心阴极灯作激发源、微波等离子体炬作原子／离子化器，建立了原子／离子荧光光谱实验装置。详细研究了微波等离子体功率、观察高度、空心阴极灯电流等因素对原子／离子荧光信号强度的影响，测量了系统对Ca的原子／离子荧光光谱的检出限。     

拉曼喷泉原子钟

利用托曼光场代替喷泉原子钟的微波腔实现拉曼喷泉原子钟.将分离托曼光场技术与冷原子喷泉技术相结合.避免了存真空腔内放置微波腔,简化了真空系统.同时还保持了很高的准确度.采用半经典理论研究了冷原子喷泉与托曼光场的相互作用过程.得到了冉赛(Ramsey)条纹.比较了托曼喷泉原子钟与热铯束拉曼原子钟,前者有更小的体积和功耗,其精度可能达到或超过商用小铯钟.还比较了拉曼喷泉原子钟与微波喷泉原子钟的差别,分析了光子反冲的影响,提出利用同向传播和相向传播的两台拉曼原子钟测最精细结构常数.     

CPT原子频标实验研究

介绍了相干布居囚禁（CPT）原子频标的小型、低功耗物理系统,并应用它开展实现了CPT原子频标的激光锁定、微波锁定方案的实验室研究.通过采用电流负反馈将激光频率锁定在原子对激光的吸收峰上,电压负反馈将微波频率锁定在电磁感应透明共振峰上,用该物理系统实现了闭环锁定的实验室桌面CPT频标实验系统.对该实验系统的频率稳定度测量获得200 s内优于5×10^-11τ^-1/2的结果. 关键词： CPT原子频标 频率稳定度 激光稳频     

微波场对电磁诱导透明谱的局域调制

当用两个微波场作用到Λ型三能级原子的耦合跃迁的基态与另两个超精细能态构成的跃迁时,由微波场诱导产生的两个高对比度共振吸收线将单重电磁诱导透明谱分裂成三个透明窗口。通过调节微波场的强度或失谐量,可实现对原子透明谱进行局域调制。采用缀饰态理论对展示的物理现象进行了解释。这些研究对多通道光通信和原子的可控调制等方面有一定的作用。     

非共振条件下∧型三能级原子系统光学双稳态和多稳态的控制

非共振条件下,我们理论研究了单向环形光腔中用一微波场驱动一个超精细低能态跃迁的∧型三能级原子系统光学双稳态和多稳态行为,结果表明原子介质双稳态的行为可以分别通过耦合场的强度和耦合场频率的失谐量控制,同时还发现微波场在实现多稳态过程中所起的重要作用.最后讨论了合作参数对光学多稳态阈值的影响.     

Microwave-Controlled Light-Pulse Propagation in a Driven Λ-Type Atomic System with Two-Folded Levels

The temporal and spatial dynamics of one weak probe laser pulse, propagating through a Λ-type atomic medium with two-folded levels under the resonant excitation of one microwave driving field and one strong control field, is investigated in this paper. By numerically solving coupled Bloch-Maxwell equations, it isfound that, in the absence of the microwave driving field, the atomic medium is transparent to the probe pulse at line center, which propagates over sufficiently long distances. By contrast, when the microwave driving field is applied, the probe pulse at line center can be rapidly absorbed on propagation. This substantial reduction of probe transmittance caused by the microwave driving field may lead to potential applications in designing a new kind of optical switching.