基于电磁感应透明效应的超慢矢量光孤子

研究基于电磁感应透明效应的A-梯型五能级原子中的超慢矢量光孤子.利用多重尺度展开法导出探测光场的左旋和右旋偏振分量所遵循的耦合非线性薛定谔方程.通过选取合适的参数,使得系统产生的克尔非线性效应与群速度色散平衡,从而探测光场的两个偏振分量可形成稳定的时间矢量光孤子.该矢量光孤子传播的速度可降至10-5c(c为真空中的光速...     

Raman型原子激光制备过程中光场的压缩特性

研究了Raman型原子激光制备过程中探测光场的压缩特性．这种原子激光是利用钠原子玻色-爱因斯坦凝聚体（BEC）与一束较弱的压缩相干态探测光和一束较强的经典泵浦光Raman跃迁相互作用制备得到的研究结果表明,压缩相干态探测光在原子激光制备过程中呈现周期性压缩,其压缩周期与原子阱中的平均原子数、光场与原子BEC相互作用强度及光场的失谐量等因素有关,压缩深度决定于探测光场的初始压缩因子．     

四能级原子系统中光脉冲的亚光速和超光速传播

提出在一个四能级原子系统中, 通过控制外加微波场的强度, 实现光脉冲的亚光速和超光速传播的理论模型. 分析了两个上能级间隔对光场群速度的影响, 并比较了四能级系统与三能级Λ系统之间的差异.      

弱光场下Y型四能级原子系统的电磁感应透明

运用数值模拟的方法精确计算了 Y 型四能级原子与外场相互作用系统对探测场的吸收和色散, 发现当系统取适当参量时, 增强控制场会使得系统对探测场的吸收减弱, 而在外加场的频率与原子能级间的跃迁频率共振时, 系统会呈现出 EIT 现象, 在另些参数下会呈现微弱的增益和较强的正常(反常)色散效应. 同时发现在探测场所对应的拉比频率相位取适当的参量时, 系统呈现了对探测光全部表现为增益的有趣现象.     

Y型四能级系统中相对位相对探测场的影响

运用密度矩阵方程理论,在自发辐射诱导相干(SGC效应)的条件下,研究了Y型四能级系统中相干光场之间的位相差对探测光场的吸收和色散性质的影响.数值模拟结果表明,通过对相对位相的控制,可以实现探测光场的吸收(增益)和色散成周期性的放大和减弱.在适当的参数取值下,相对位相为=α时的色散曲线与=α+π/2时的吸收(增益)曲线类似;当变化π时,系统色散曲线会发生反转,系统呈现光学双稳效应,这对量子逻辑门的研究有着重要的理论意义.     

线偏振谐波光场中的二能级原子

原子与光场相互作用系统是很难求解的 ,对二能级原子与线偏振谐波光场相互系统进行了求解 ,得出了二能级原子与线偏振谐波光场相互作用系统的波函数、系统能量的可能取值、二能级原子动量的可能取值。     

线偏振谐波光场中的二能级原子

原子与光场相互作用系统是很难求解的，对二能级原子与线偏振谐波光场相互系统进行了求解，得出了二能级原子与线偏振谐波光场相互作用系统的波函数、系统能量的可能取值、二能级原子动量的可能取值。     

二项式光场与V-型量子拍频三能级原子作用系统中光场的压缩效应

研究了二项式光场与V 型量子拍频三能级原子作用系统中光场的压缩特性及系统参数对光场压缩的影响 .数值计算表明 :当光场与三能级原子作用失谐量增大时 ,光场涨落呈现出周期性 ,平均值下移 ,压缩时间延长 ;选择合适的系统参数可使光场完全被压缩 ,产生完全压缩光 .     

K模辅射场与二能级原子作用系统中原子的偶极压缩

利用J-C模型,在旋波近似下,给出了K模相干光场与二能级原子相互作用系统中系统态矢的演化。利用数值计算方法研究了三模相干光场与二能级原子相互作用系统中原子的偶极压缩效应,讨论了初始光场强度和光场相位对原子的偶极压缩效应的影响。结果表明:当初始光场较强时,原子只在演化的初期呈现短暂的间隙性压缩效应,光场相位决定原子的压缩方向,而光场强度变化对原子的偶极压缩效应影响很小。     

大失谐下纠缠原子与场作用过程中的光场特性

研究在大失谐条件下两全同二能级纠缠原子与相干态光场相互作用过程中系统的光场特性,采用时间演化算符和数值计算方法讨论了系统参数对系统光场特性的影响。研究表明:单模相干光场和两全同二能级纠缠原子在大失谐作用条件下,无论如何调整系统参数,都无法使光场压缩。     

Active optical clock based on four-level quantum system

Active optical clock,a new conception of atomic clock,has been proposed recently.In this work,we propose a scheme of active optical clock based on four-level quantum system.The final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic beam.To three-level quantum system,they are mainly limited by light shift of pumping laser field.These limitations can be avoided effectively by applying the scheme proposed here.Rubidium atom four-level quantum system,as a typical example,is discussed.The population inversion between 6S 1/2 and 5P 3/2 states can be built up at a time scale of 10-6 s.With the mechanism of active optical clock,in which the cavity mode linewidth is much wider than that of the laser gain profile,it can output a laser with quantum-limited linewidth narrower than 1 Hz in theory.An experimental configuration is designed to realize this active optical clock.     

在相干外场作用下的V型三能级原子对探测光吸收性质的研究

采用一个相干外场作用到V型三能级原子系统的激发态与另一个激发态构成的跃迁上,发现该外加相干光场对该原子气体吸收性质有很大的影响,当该光场的强度在一定范围内时,探测光会被放大.     

Coherent control of optical information with matter wave dynamics

In recent years, significant progress has been achieved in manipulating matter with light, and light with matter. Resonant laser fields interacting with cold, dense atom clouds provide a particularly rich system. Such light fields interact strongly with the internal electrons of the atoms, and couple directly to external atomic motion through recoil momenta imparted when photons are absorbed and emitted. Ultraslow light propagation in Bose-Einstein condensates represents an extreme example of resonant light manipulation using cold atoms. Here we demonstrate that a slow light pulse can be stopped and stored in one Bose-Einstein condensate and subsequently revived from a totally different condensate, 160 mum away; information is transferred through conversion of the optical pulse into a travelling matter wave. In the presence of an optical coupling field, a probe laser pulse is first injected into one of the condensates where it is spatially compressed to a length much shorter than the coherent extent of the condensate. The coupling field is then turned off, leaving the atoms in the first condensate in quantum superposition states that comprise a stationary component and a recoiling component in a different internal state. The amplitude and phase of the spatially localized light pulse are imprinted on the recoiling part of the wavefunction, which moves towards the second condensate. When this 'messenger' atom pulse is embedded in the second condensate, the system is re-illuminated with the coupling laser. The probe light is driven back on and the messenger pulse is coherently added to the matter field of the second condensate by way of slow-light-mediated atomic matter-wave amplification. The revived light pulse records the relative amplitude and phase between the recoiling atomic imprint and the revival condensate. Our results provide a dramatic demonstration of coherent optical information processing with matter wave dynamics. Such quantum control may find application in quantum information processing and wavefunction sculpting.     

基于改进的SOA-MZI全光分组头提取方案

在光域实现分组头的提取是全光分组交换实现的关键技术之一。提出一种基于控制光与探测光同向传输的改进半导体光放大器(SOA)-马赫曾德尔干涉仪(MZI)性能的全光分组头提取方案。该方案利用控制光及探测光分别调节SOA的增益,结合马赫曾德尔干涉仪的干涉原理实现光域净荷抑制和分组头的提取。研究分析了该方案的一组系统优化参数。数值分析和仿真结果表明：在光分组头速率和净荷速率都为100 Gbit/s时,提取光分组头的对比度高于18 dB。     

环形腔吸收型光学双稳器件的静态研究

本文以二能级均匀展宽原子系统的 Maxwell—Bloch 方程的静态解为基础,对环形腔吸收型光学双稳器件作了较全面的静态研究。推导出了此器件具有光放大性的条件和光放大区的范围,求出了此双稳器件差分增益的最大值,及此时的归一化入射光强和透射光强,并推导出了此器件差分增益最大值随合作参数的变化规律。同时,证明了这一器件不可能作为光强稳定器。     

Pr∶YSO晶体中基于光存储的频率转换

基于电磁感应光透明导致的光存储效应, 在四能级双Lambda系统的Pr〖KG*9〗∶〖KG-*2〗YSO晶体中,  实验研究光信息在两个不同频率通道间的转换. 结果表明: 在电磁感应光透明的条件下, 当一个弱的探测脉冲通过晶体时, 其群速度减慢, 实验观测到的群速度为86 m/s; 当慢光脉冲在晶体中传输时, 在绝热条件下关闭相干控制场, 此时探测场光脉冲的部分相干光学信息将存储于晶体内部; 在光信息释放过程中, 通过开启不同方向及频率的两个控制场, 存储的光信息会由原慢光脉冲单一通道转换为两个具有不同频率和方向的光脉冲通道进行释放. 在释放过程中调整两个控制场可实现慢光信息在两个不同频率通道间的相互转换.     

Logistic曲线拟合与预测在我国旅游市场中的应用

讨论了外加驱动场和原子介质自发辐射量子相干来调控固定腔中四能级原子介质的古斯-汉欣位移.研究表明,原子介质的自发辐射量子相干对古斯-汉欣位移的影响较大,在具有一定强度的自发辐射量子相干时,外加驱动场的强度和失谐对透射光和反射光的古斯-汉欣位移调控最为明显,可以实现大的古斯-汉欣位移.     

暗态共振相干下的非线性增强(英文)

目的研究双暗态共振四能级系统中三阶非线性的增强。方法利用缀饰态理论,得到了弱探测场线性和非线性磁化率的解析表达式。结果与结论结果表明,双电磁感应透明和自克尔非线性的特性可以通过两个耦合场相对强度的改变来控制。     

Observation of coherent optical information storage in an atomic medium using halted light pulses

Electromagnetically induced transparency is a quantum interference effect that permits the propagation of light through an otherwise opaque atomic medium; a 'coupling' laser is used to create the interference necessary to allow the transmission of resonant pulses from a 'probe' laser. This technique has been used to slow and spatially compress light pulses by seven orders of magnitude, resulting in their complete localization and containment within an atomic cloud. Here we use electromagnetically induced transparency to bring laser pulses to a complete stop in a magnetically trapped, cold cloud of sodium atoms. Within the spatially localized pulse region, the atoms are in a superposition state determined by the amplitudes and phases of the coupling and probe laser fields. Upon sudden turn-off of the coupling laser, the compressed probe pulse is effectively stopped; coherent information initially contained in the laser fields is 'frozen' in the atomic medium for up to 1 ms. The coupling laser is turned back on at a later time and the probe pulse is regenerated: the stored coherence is read out and transferred back into the radiation field. We present a theoretical model that reveals that the system is self-adjusting to minimize dissipative loss during the 'read' and 'write' operations. We anticipate applications of this phenomenon for quantum information processing.