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1.
Dynamics of a two-level atom moving in an electromagnetic field is studied. The atomic motion gives rise to a momentum-dependent detuning which holds back the atomic transition, and leads to a momentum-dependent Rabi oscillation which causes an overlapping among different Rabi oscillations. When the field is in a Fock state, the atomic population and the mean momentum of the atom exhibit damping oscillation, the damping rate is related to the momentum distribution; the collapse-revival phenomena of the atomic population and the mean momentum will occur if the atomic momentum has some special distribution. When the field is in a superposition state, the collapse-revival phenomena are modified by the atomic momentum distribution and disappear for the wider atomic momentum wavepackets. We also find that each atomic level will split into two sublevels with the same energy difference when the field is in a Fock state and the atom has a definite momentum. 相似文献
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分析了一个运动的三能级原子与一个驻波激光场地斜交相互作用时的动量传递行为。结果表明,当原子和光场由于多普勒效应满足一定条件时,将产生受激拉曼跃迁。如果作用光相对于原子而言为一个“π/2脉冲”光时,那么经过作用后,原子将处于一个相干迭加态,其中一个态与加始相同。 相似文献
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高Q Kerr介质腔中二项式光场与原子相互作用 总被引:6,自引:4,他引:2
应用全量子理论研究了在高Q Kerr介质腔中, 二能级原子与二项式光场相互作用系统中原子行为和光场的量子特性. 采用数值计算的方法, 详细讨论了光场参量和Kerr效应对原子布居反转和平均光子数的影响.研究发现当二项式光场处在中间态时, 在考虑Kerr效应的条件下,原子布居振荡加剧, 回复时间变短, 系统内平均光子数减少. 相似文献
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Inrecentexperimentsonlasercoolingandtrappingtheobservationofquantumefectsrelatedtotheatomiccentreofmasmotion(CM)hasbeenrepo... 相似文献
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M. S. Ateto 《International Journal of Theoretical Physics》2010,49(2):276-292
The wave function of a system governed by the time-dependent nonlinear Jaynes-Cummings (JC) model is obtained. We compute
analytically the eigenvalues of the reduced field density operator by which the dynamics of the entropy of entanglement of
the cavity field are analyzed. The influences of the atomic motion, the field-mode structure and the Kerr-like medium on this
phenomenon are illustrated. The population dynamics of an excited atom is also discussed for the same set of parameters. The
cavity field is assumed to be initially excited in either a Fock or a coherent states. The cavity excitation in a Fock state
generates a class of an entanglement without death with fixed amplitude by adjusting the parameters of the atomic motion as
well as the Kerr and the field-mode structure. In case of a coherent cavity, the only phenomenon to be noted is the periodical
behavior of the dynamics under study when the atomic motion is considered. Although the Kerr medium affects the strength of
the entanglement negatively, the entropy of entanglement loses its zeros where the Kerr is taken into consideration. 相似文献
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GENERATION OF ENTANGLED FOCK STATES OF TWO NONLOCAL CAVITY MODES WITH DIFFERENT FREQUENCIES 总被引:1,自引:0,他引:1
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We present a method to generate entangled Fock states of two nonlocal cavity modes with different frequencies. We send an atom with three levels g,e, and f across two cavities. The atomic transition frequency between level g and e is resonant with the first cavity frequency, while the atomic transition frequency between level g and f is resonant with the second cavity frequency. The detection of the atomic state leaves the pure field in an entangled Fock state. 相似文献
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A. V. Andreev S. Yu. Stremoukhov O. A. Shutova 《Radiophysics and Quantum Electronics》2011,54(2):128-144
We develop the theory of interaction of the electromagnetic field and a single atom being in an arbitrary state and having
an arbitrary direction of the angular momentum of the atomic electron with respect to the direction of the field polarization
vector. It is shown that the atom response current has a tensor structure and depends on both the direction of the angular
momentum of the atom, and the polarization vector of the external field. The tensor character of the response is determined
by the externally induced anisotropic distribution of the probability density of spatial localization of the atomic electron.
It is shown that the induced-anisotropy effects clarify the harmonic generation mechanism at play during the non-resonance
interaction of laser radiation with atomic media. The developed theory is applied to the analysis of the problem about the
generation of terahertz waves in a two-color laser field. It is shown that the change in the mutual orientation of wave polarization
vectors leads to a significant increase in the efficiency of conversion of high-frequency fields to low-frequency ones. It
is shown for the first time that the generation of terahertz waves is possible in the preionization regime, when the generation
mechanism is related to atomic nonlinearity. 相似文献
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Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium 总被引:1,自引:0,他引:1
ZHOU Qing-Chun 《理论物理通讯》2006,45(4):727-730
By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode field in a Kerr-like medium.The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account. 相似文献
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Magdy E. Amin N. H. Abdel-Wahab M. Taha 《International Journal of Theoretical Physics》2004,43(2):411-420
We study the interaction between a one-mode electromagnetic field and a two-level atom in the presence of a Kerr-like medium when the atom is prepared initially in the momentum eigenstate. The wave function is calculated by using the Schrodinger equation for a coherent electromagnetic field and an atom in the excited state. The effects of the Kerr-like medium and the detuning parameters on the statistical aspects of the intensity-dependent-coupling Hamiltonian such as, atomic momentum increment, momentum diffusion, the radiation force, and the field entropy are calculated. We investigate the effect of the detuning, Kerr-like medium and photon number operator on the field entropy. 相似文献
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A. V. Kozlovskiĭ 《Journal of Experimental and Theoretical Physics》2007,104(4):515-526
A numerical analysis of dispersive quantum nondemolition measurement of the photon number of a microwave cavity field is presented. Simulations show that a key property of the dispersive atom-field interaction used in Ramsey interferometry is the extremely high sensitivity of the dynamics of atomic and field states to basic parameters of the system. When a monokinetic atomic beam is sent through a microwave cavity, a qualitative change in the field state can be caused by an uncontrollably small deviation of parameters (such as atom path length through the cavity, atom velocity, cavity mode frequency detuning, or atom-field coupling constants). The resulting cavity field can be either in a Fock state or in a super-Poissonian state (characterized by a large photon-number variance). When the atoms have a random velocity spread, the field is squeezed to a Fock state for arbitrary values of the system’s parameters. However, this makes detection of Ramsey fringes impossible, because the probability of detecting an atom in the upper or lower electronic state becomes a random quantity almost uniformly distributed over the interval between zero and unity, irrespective of the cavity photon number. 相似文献
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Entropy squeezing of the field interacting with a nearly degenerate V-type three-level atom
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The position- and momentum-entopic squeezing properties of the optical field in the system of a nearly degenerate three-level atom interacting with a single-mode field are investigated. Calculation results indicate that when the field is initially in the vacuum state, it may lead to squeezing of the position entropy or the momentum entropy of the field if the atom is prepared properly. The effects of initial atomic state and the splitting of the excited levels of the atom on field entropies are discussed in this case. When the initial field is in a coherent state, we find that position-entropy squeezing of the field is present even if the atom is prepared in the ground state. By comparing the variance squeezing and entropy squeezing of the field we confirm that entropy is more sensitive than variance in measuring quantum fluctuations. 相似文献
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A theory of the nonresonant response of a single atom in a state with arbitrary magnitude and direction of the angular momentum
of an atomic electron with respect to the polarization vector of the acting electromagnetic field has been developed. It has
been shown that the atomic response current has a tensor structure and depends both on the direction of the angular momentum
of the atom and on the polarization vector of the external field. The tensor character of the response is due to the effects
of the anisotropy of probability density distribution of the atomic electron as compared to the case of the free atom. The
selection rules for the axisymmetric problem of the atom in the field have been analyzed. The manifestation of the selection
rules in the angular spectra of photoelectrons has been demonstrated. The probability of the ionization of the atom has been
analyzed as a function of the amplitude and duration of the pulse. It has been shown that the width of the generation spectrum
is a nonlinear function of the field strength and is saturated in the region of nearly atomic fields. Methods for controlling
the parameters of the atomic response spectrum have been proposed on the basis of the use of a sequence of laser pulses with
various time profiles, carrier frequencies, and polarization states. It has been shown that the generation of terahertz radiation
is possible in the preionization regime, where the generation mechanism is attributed to atomic nonlinearity. 相似文献
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A. V. Kozlovskiĭ 《Journal of Experimental and Theoretical Physics》2008,107(3):356-363
The dynamics of energy exchange between an atom moving in a high-Q cavity and the cavity field is analyzed by taking into account the Roentgen interaction. A two-level atom coupled to a Fock or coherent state of an optical or microwave cavity is considered. The mean cavity photon number required for high-frequency Doppler-Rabi oscillations to occur is relatively high for both Fock-and coherent-state cavity fields and increases with the atomic transition frequency. Conditions are found when the Roentgen interaction plays a key role in the Doppler-Rabi oscillations and must be taken into account, in addition to the conventional electric field-dipole interaction. 相似文献
16.
《Physics letters. A》1999,254(6):301-306
A simple scheme for quantum non-demolition (QND) measurement of a Fock state stored in a high-Q cavity is proposed. esscheme utilizes well-defined atomic center-of-mass momentum states in wave propagation direction, interacting with an offresonant cavity field in the Bragg regime. The same scheme can be applied for the formation of quantum Controlled-NOT logic gate. 相似文献
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S. V. Prants 《Journal of Experimental and Theoretical Physics》2009,109(5):751-761
A quantum analysis is presented of the motion and internal state of a two-level atom in a strong standing-wave light field. Coherent evolution of the atomic wave-packet, atomic dipole moment, and population inversion strongly depends on the ratio between the detuning from atom-field resonance and a characteristic atomic frequency. In the basis of dressed states, atomic motion is represented as wave-packet motion in two effective optical potentials. At exact resonance, coherent population trapping is observed when an atom with zero momentum is centered at a standing-wave node. When the detuning is comparable to the characteristic atomic frequency, the atom crossing a node may or may not undergo a transition between the potentials with probabilities that are similar in order of magnitude. In this detuning range, atomic wave packets proliferate at the nodes of the standing wave. This phenomenon is interpreted as a quantum manifestation of chaotic transport of classical atoms observed in earlier studies. For a certain detuning range, there exists an interval of initial momentum values such that the atom simultaneously oscillates in an optical potential well and moves as a ballistic particle. This behavior of a wave packet is a quantum analog of a classical random walk of an atom, when it enters and leaves optical potential wells in a seemingly irregular manner and freely moves both ways in a periodic standing light wave. In a far-detuned field, the transition probability between the potentials is low, and adiabatic wave-packet evolution corresponding to regular classical motion of an atom is observed. 相似文献
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By using the theory of cavity QED, we study the system in which a two-level atom interacts with a cavity in the case of large detuning. Through the selective detecting of atomic state, Schrodinger cat states and entangled coherent states are easily generated. When the atom is driven by a weak classical field and the cavity field is in the Schrodinger cat state, we study the conditions of generating the Fock states and the maximal success probability. The maximal success probability in our scheme is larger than the previous one. 相似文献
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研究了两个二能级原子与一个单模腔场的相互作用中,腔场的不同初始态对原子间相对位置退相干的影响。从描述原子间相对位置状态的约化密度矩阵出发,假设原子间相对位置为两个高斯波包的叠加态,讨论了当腔场初始态分别为热态、Fock态和压缩态情况下,原子与光场的相互作用对两原子间相对位置相干性的影响。发现腔场的初始态不同,原子间相对位置的退相干情况有所不同。当腔场初始态为热态或Fock态时,原子间相对位置的相干性会周期性的衰减和回复,而当腔场初始态为压缩态时,原子间相对位置会出现部分退相干,且退相干程度与原子间相对位置的大小成余弦变化关系。 相似文献