微波场驱动下V型三能级原子的吸收和色散特性

当用微波场作用到V型三能级原子的两个激发态能级时,系统跃迁路径之间发生交叉耦合导致了量子相干效应.通过调节微波场的强度,可实现对原子吸收和色散性质的改变,并呈现零吸收高折射率现象.此外,微波场诱导的量子相干也可实现相对相位对探测光增益的控制.     

微波场驱动下V型三能级原子的吸收和色散特性

当用微波场作用到V型三能级原子的两个激发态能级时,系统跃迁路径之间发生交叉耦合导致了量子相干效应.通过调节微波场的强度,可实现对原子吸收和色散性质的改变,并呈现零吸收高折射率现象.此外,微波场诱导的量子相干也可实现相对相位对探测光增益的控制.     

基于里德伯原子电磁诱导透明效应的光脉冲减速

6S1/2→6P3/2→49D5/2基于铯里德伯原子的电磁诱导透明效应,当光与原子能级频率共振时,色散将剧烈变化,吸收减弱.此时光脉冲在原子介质中传播时,将会出现减速.在铯原子阶梯型三能级系统中,观察到由色散曲线陡峭变化导致的探测光脉冲减速现象,并系统研究了耦合光强度和原子气室温度对光脉冲减慢的影响.实验结果表明,耦合光越弱,延迟时间越长;原子气室温度越高,减速效应越明显,与理论计算相符.实验结果为之后进行的通过光脉冲减速效应测量微波电场提供了实验基础.     

简单三能级原子介质中由量子干涉引起的折射率增强

考虑具有一相干驱动场的简单三能级原子模型,探讨该系统的色散、吸收特性,得到在强相干驱动场条件下,可导致该介质对弱探测场的透明;该三能级原子系统能够用来产生一超大折射率. 关键词：     

非对称耦合量子阱吸收与色散的理论研究

基于V型三能级模型研究了非对称耦合量子阱（ACQW）线性吸收与色散特性. 理论结果表明：在小偏置区，由沿生长方向的外加电场引起的强量子限域Stark频移导致非共振吸收，线性折射率大幅度降低，表现为色散猝灭特性. 而随负偏压进一步增加, 由于量子限域Stark效应消失，其吸收与色散特性则与单量子阱最低激子态相类似. 这意味着ACQW具有随外加电场变化的可控色散特性. 关键词： 非对称耦合量子阱 量子相干 可控色散     

49S里德堡态的射频双光子光谱

在室温铯原子蒸气池中, 由铯原子基态、激发态和里德堡态构建了阶梯型三能级系统, 研究了里德堡原子阶梯型三能级系统的电磁感应透明(EIT). 在实现电磁感应透明的基础上, 利用16.9 GHz的射频电场耦合相邻的原子里德堡态, 实现49S_1/2→47D_3/2的双光子跃迁, 测量了里德堡原子的射频双光子光谱, 观察到了电磁感应透明光谱的分裂, 进一步研究了电场强度对射频双光子光谱的影响. 利用里德堡原子的EIT效应可实现对射频电场幅值和极化的精密测量, 具有潜在的应用前景.     

四能级系统中的原子相干效应

讨论了N型四能级原子系统中的原子相干效应，与三能级原子系统相比，其原子相干效应既可导致电磁感应透明(EIT，Electromagnetically Induced Transparency)的产生，也可产生电磁感应吸收(EIA，Electromagnetically Induced Absorption)现象，取决于控制光的强度和第四个能级的衰变率的大小。     

基于马赫-曾德干涉法测量原子介质的色散特性

理论分析了利用马赫-曾德干涉仪及平衡零拍探测技术测量相干介质色散特性的方法,实验测量了三能级铯原子分别在电磁诱导透明和电磁诱导吸收两种截然相反的相干效应下的色散特性.研究表明:在原子频率共振中心,对于透明介质,由于吸收减弱效应,信号光能穿出介质,保证了有效色散信息,即正常色散特性能被测量到;相反地,对于吸收介质,由于强吸收效应,只有在低粒子数密度条件下,即保证有信号光没有被完全吸收而穿出介质,才能测量到介质的反常色散特性;当提高铯泡温度时,介质对信号光吸收增强以至完全吸收,并且吸收频谱宽度变宽,导致色散信息不能被有效测量到.     

级联型三能级原子与单模光场耦合系统中的场量子特性

利用J-C模型,采用数值计算方法研究了相干态光场与级联型三能级原子相互作用过程中场的压缩效应和反聚束效应。讨论了选择原子测量对相干态光场与级联型三能级原子相互作用过程中场压缩效应和反聚束效应的影响。     

光学-射频场双驱动原子系统中的透明与吸收特性的调控

光与物质的相互作用可以产生许多奇特的量子光学现象,电磁诱导透明和电磁诱导吸收是其中最典型的现象.本文在通常的Λ型三能级系统中引入射频场作用于激发态的精细结构能级之间,组成光学-射频双驱动场共同激发原子的相干跃迁,使系统的吸收特性出现电磁诱导透明和电磁诱导吸收两种量子相干效应.通过讨论双驱动场开启后直到系统达到稳定的量子相干过程,分析电磁诱导透明和电磁诱导吸收随时间的产生和转化,得到两种量子相干现象之间的关联性及对其进行量子调控的方法.     

Exactly solvable dicke models and radiation dragging

6. Conclusion We have investigated various exactly solvable Dicke-model cases describing the interaction of two- or three-level atoms with the electromagnetic field in an ideal cavity. In Secs. 2 and 3 are considered two-level atoms, one or two of which are excited at the initial instant of time; both symmetric and asymmetric excitations are considered. In addition, solutions are presented for the case when there are no excited atoms at the initial instant of time, but one or two photons are present. It is shown that in the case of symmetric initial conditions superradiance is present in a certain sense, whereas asymmetric initial conditions lead to the effect of "radiation dragging" from one or two atoms for a very large total number of atoms. In Sec. 4 it is shown that radiation dragging takes place also in the case of asymmetric initial excitation of an arbitrary number m of two-level atoms in the presence of a very large number n of atoms in the ground state. The radiation-dragging condition is the inequality m < < n. Furthermore, in Sec. 5 are considered symmetric and asymmetric excitations of one of N three-level atoms interacting with two or more field modes. The different configurations of the atomic levels (ladder and Λ cases) are considered). It turns out that in addition to radiation dragging due to asymmetric initial conditions, there appears for the ladder configuration an additional absence of radiation from the upper level of the atom in the case of symmetric initial conditions. This additional vanishing of the radiation occurs also in the equidistant ladder three-level case, when transitions between neighboring level pairs result from interaction with one field mode. The authors are deeply grateful to V. I. Man’ko for interest in the work, and to é. A. Akhundova and V. P. Karasev for helpful discussions. Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 191, pp. 150–170, 1989.     

Phase control of probe response in an open ladder type system with spontaneously generated coherence

The control role of the relative phase between the probe and driving fields on the gain and dispersion in an open three-level ladder atomic system with incoherent pumping and spontaneously generated coherence is investigated. It is shown that by adjusting the value of the relative phase, the switching from lasing with inversion to lasing without inversion (LWI) can be realized; high index of the refraction with zero absorption can be achieved. It is also found that when the driving field is on resonance, the dispersion curve versus the probe detuning is very similar to the gain curve if the relative phase corresponding to the dispersion advances π/2 than that corresponding to the gain. LWI gain from the open system is obviously larger than that from corresponding closed system. When the incoherent pumping is absent, the open system can get LWI gain, moreover the gain is larger than that when the incoherent pumping presents for suitable value of the relative phase, but the corresponding closed system exhibits only absorption. In addition, manipulation effects of atomic exit and ratio of the injection rates on phase dependent gain are also analyzed.     

Phase Time for the Tunneling of Ultracold V-Type Atoms Through a Mazer Cavity

We study the tunneling time of ultracold V-type atoms interacting a high quality microwave cavity. Here atomic coherence is introduced in the system by a strong driving field which couples the two lower states of the three-level atom. It is found that in the presence of coherence, mazer action or the scattering like nature of the interaction may be examined for extended energies of the incident cold atoms. Our results show that position and amplitudes of the peak values of the phase time(traversal time) may be very effectively controlled by the coherent driving field. Further, here we obtained superclassical values of the phase time corresponding to much higher values of the transmission amplitudes of the tunneling atoms which may be advantageous in the possible experimental realization of the superclassical tunneling time of the traversing cold atoms. In addition, we examine a mirror reflection type symmetry in the phase time curve for a judicious choice of the external driving field.     

调制激光场中Rydberg原子的电磁感应透明

本文主要研究了调制探测激光场中铯Rydberg 原子阶梯型三能级系统的电磁感应透明(EIT) 效应. 铯原子基态6S_1/2, 第一激发态6P_3/2 和Rydberg 态形成阶梯型三能级系统, 探测光作用于6S_1/2 (F = 4)→6P_3/2(F' = 5) 的跃迁, 耦合光在Rydberg 跃迁线6P_3/2→49S_1/2 附近扫描, 形成Rydberg 原子EIT. 当对探测光频率施加一个几kHz 的调制时, 调制解调后的EIT 信号分裂为两个峰, 双峰间距与调制频率无关,而与调制幅度导致的失谐量大小(频率调制幅度) 成正比, 双峰间隔的一半等于探测光频率调制幅度的λ_p/λ_c = 1.67 倍. 实验结果与理论计算相一致. 本文的研究结果可应用于激光线型和频率抖动的实时监测.     

Effect of vacuum-induced coherence on lasing without inversion in an equispaced three-level ladder system

The effects of vacuum-induced coherence (VIC) on the properties of the absorption and gain of the probe field in an equispaced three-level ladder atomic system are investigated. It is found that lasing without inversion (LWI) is remarkably enhanced due to the effect of VIC in the case of the small incoherent pump rate.     

Correlated photon emission from multiatom Rydberg dark States

We consider three-level atoms driven by two resonant light fields in a ladder scheme where the upper level is a highly excited Rydberg state. We show that the dipole-dipole interactions between Rydberg excited atoms prevents the formation of single particle dark states and leads to strongly correlated photon pairs from atoms separated by distances large compared to the emission wavelength. For a pair of atoms, this enables realization of an efficient photon-pair source with on average one pair every 30 μs.     

利用V-型三能级原子与双模腔场双光子大失谐相互作用制备W纠缠态

本文提出利用V-型三能级原子与双模腔场的双光子大失谐相互作用制备W纠缠态,该方案要求三个三能级原子和一个双模腔场,第一个与腔场作用的原子最初处于激发态,第二个和第三个原子均处于基态,腔场最初处于真空态,合适地选择原子与腔场之间的相互作用时间即可获得三原子W纠缠态.并且此方案可以推广至多原子W纠缠态和多腔场W纠缠态的制备;通过计算共生纠缠度研究系统中态的纠缠演化以及热纠缠现象.