共查询到20条相似文献,搜索用时 15 毫秒
1.
E. K. Bashkirov 《Laser Physics》2006,16(8):1218-1226
An exact solution is found for the collective model of two identical two-level atoms that resonantly interact with a two-mode quantum electromagnetic field in an ideal cavity via two-photon nondegenerate transitions. In the case under study, at the initial moment, both field modes are in the coherent state and atoms are in the excited state. The time dependences of the atomic probabilities, the mean number of photons in the modes, and the statistics and squeezing of the photon modes are studied based on the exact solution. 相似文献
2.
An exact solution of the problem of two two-level atoms with nondegenerate two-photon transitions and nondegenerate Raman transitions interacting with two-mode radiation field is presented. Asymptotic solutions for system state vectors are obtained in the approximation of large initial coherent fields. The atom-field entanglement is investigated on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process for both models is shown. Conditions and times of disentanglement are derived. 相似文献
3.
The dynamics of atom–field entanglement for two two-level atoms with degenerate two-photon transitions interacting with one-mode radiation field with taking into account the Stark shift is investigated. Asymptotic solutions for system state vectors are obtained in the approximation of large initial coherent fields. The atom–field entanglement is investigated also on the basis of the linear atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process is shown. Conditions and times of disentanglement are derived. 相似文献
4.
We study the evolution of entanglement for a pair of two-level Rydberg atoms passing one after another into an ideal cavity filled with a single mode radiation field. The atoms interact with the cavity field via two-photon transitions. The initial joint state of two atoms that enter the cavity one after the other is unentangled. Interactions intervened by the single mode cavity photon field brings out the final two-atom mixed entangled type state. We use the well known measure appropriate for the mixed states, i.e. the entanglement of formation to quantify the entanglement. We calculate the entanglement of formation of the joint two-atom state as a function of the Rabi angle, for the Fock state field, coherent field and thermal field respectively inside the cavity. The change in the magnitude of atomic entanglement with cavity photon number has been discussed. 相似文献
5.
Considering two identical two-level atoms interacting
with a single-mode thermal
field through two-photon processes,
this paper studies the atomic coherence control on the
entanglement between two two-level atoms,
and finds that the entanglement is greatly
enhanced due to the initial atomic coherence. The results show
that the entanglement can be manipulated
by changing the initial
parameters of the system, such as the superposition coefficients
and the relative phases
of the initial atomic coherent state and the mean photon
number of the cavity field. 相似文献
6.
Entropy squeezing of a moving atom and control of noise of the quantum mechanical channel via the two-photon process
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Based on the quantum information theory, we have investigated the
entropy squeezing of a moving two-level atom interacting with the
coherent field via the quantum mechanical channel of the two-photon
process. The results are compared with those of atomic squeezing
based on the Heisenberg uncertainty relation. The influences of the
atomic motion and field-mode structure parameter on the atomic
entropy squeezing and on the control of noise of the quantum
mechanical channel via the two-photon process are examined. Our
results show that the squeezed period, duration of optimal entropy
squeezing of a two-level atom and the noise of the quantum mechanical
channel can be controlled by appropriately choosing the atomic motion
and the field-mode structure parameter, respectively. The quantum
mechanical channel of two-photon process is an ideal channel for
quantum information (atomic quantum state) transmission. Quantum
information entropy is a remarkably accurate measure of the atomic
squeezing. 相似文献
7.
V. A. Sautenkov S. A. Saakyan E. V. Vilshanskaya B. B. Zelener B. V. Zelener 《Journal of Russian Laser Research》2017,38(1):91-95
We study power broadening of coherent two-photon resonances on Rydberg transitions in lithium-7 atoms in a magneto-optical trap (MOT). We apply the spectroscopic technique based on the reduction of resonance fluorescence in the MOT. One of the main contributions to the spectral broadening is associated with heating of the trapped atoms by laser cooling beams. We suggest a new nondestructive method to measure the atomic temperature in a working MOT using two-photon spectroscopy with variable directions of probe beams. 相似文献
8.
Mudassar Aqueel Ahmad 《Optics Communications》2008,281(6):1635-1646
In this paper, we study the quantum phase properties of the field in a two-photon micromaser, including the effects of the finite detuning of the intermediate level. For initial coherent state of the cavity field and atoms initially in their excited state multipeak phase structure appears which eventually leads to the randomization of the cavity field phase. However, the approach towards the randomization depends upon the detuning. If the atoms are injected in a coherent superposition of their upper and lower atomic states then the phase distribution evolves into two-peak structure. For initial thermal state and atoms in polarized state, cavity field acquires some phase. We also consider the effect of finite Q of the cavity, random injection of the atoms and fluctuations in the interaction time. 相似文献
9.
Sunil Kumar 《Pramana》1985,25(3):291-309
The theory of the coherent, two-photon resonant interaction of a monochromatic field with N atoms is given. It is seen that
the dynamics of the atom-field system can be completely determined when the field is “strong”. Two specific examples are given:
(i) two-photon absorption by atoms in ground state, and (ii) stimulated two-photon emission by fully excited atoms, assuming
a coherent field in both cases. In case (ii), the field shows photon-antibunching after the decay of half of the atoms. The
merits of our approach are shown by comparing with other treatments. Our results can also be applied to certain degenerate
four-wave mixing processes which are described by a similar Hamiltonian. 相似文献
10.
Entanglement of two artificial two-level atoms with degenerate two-photon transitions is considered in the case in which the atoms interact with the thermal single-mode field in an ideal cavity. The possibility of controlling the atomic entanglement degree in such a system due to the induction of atomic coherence and direct dipole-dipole interaction of atoms is shown. 相似文献
11.
In this paper, we have studied the field and atomic dipole squeezing in the two-photon Jaynes-Cummings model when it is restricted to the following initial condition: the field in the thermal state and the atom in a coherent state. The relationship between the field and atomic dipole squeezing has also been discussed in detail. 相似文献
12.
The nonclassical squeezing effect emerging from a nonlinear coupling model (generalized Jaynes–Cummings model) of a two-level atom interacting resonantly with a bimodal cavity field via two-photon transitions is investigated in the rotating wave approximation. Various Bloch coherent initial states (rotated states) for the atomic system are assumed, i.e., (i) ground state, (ii) excited state, and (iii) linear superposition of both states. Initially, the atomic system and the field are in a disentangled state, where the field modes are in Glauber coherent states via Poisson distribution. The model is numerically tested against simulations of time evolution of the based Heisenberg uncertainty relation variance and Shannon information entropy squeezing factors. The quantum state purity is computed for the three possible initial states and used as a criterion to get information about the entanglement of the components of the system. Analytical expression of the total density operator matrix elements at t > 0 shows, in fact, the present nonlinear model to be strongly entangled, where each of the definite initial Bloch coherent states is reduced to statistical mixtures. Thus, the present model does not preserve the modulus of the Bloch vector. 相似文献
13.
An experimental investigation of the coherent interaction of femtosecond pulses with two resonant sequential transitions of Rb atoms is presented. Fluorescence from the atomic system exhibits beating at a frequency given by difference in the sequential atomic transitions. The results are interpreted in terms of quantum interference in the induced coherence and its interaction with the field that results from a cooperative emission process. 相似文献
14.
H.P. Yuen 《Physics letters. A》1976,56(2):105-106
Under a radiation power constraint, the maximum signal-to-quantum noise ratio obtainable for any state of a radiation field is found. This maximum value is achieved by the two-photon coherent states introduced previously to describe two-photon lasers. 相似文献
15.
16.
SU(2)相干态场与二能级原子的非简并双光子相互作用 总被引:5,自引:0,他引:5
研究了双模SU(2)相干态场与腔中二能级原子的非简并双光子相互作用。用数值计算讨论了SU(2)光场的反关联特性对原子动力学行的影响及场的量子统计性质时间的演化。 相似文献
17.
We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium D1 line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch. 相似文献
18.
Using the two-mode two-photon Jaynes-Cummings model, entanglement transfer between atoms and field is studied. It is found that when the field is in state constructed from the two-mode photon number states |00〉,|11〉 or the two-mode squeezed vacuum states, full entanglement exchange can be attained no matter the atoms are initially in pure or mixed states. These investigations show that CV entangled states can act as perfectly as the entangled number states in entangling initially separable atoms. The two-mode two-photon atom-field interaction also provides a simple way for the quantum teleportation of atomic or field states. 相似文献
19.
HUANG Hongbina) b) XING Linglingc) SONG Jiliangd) 《Chinese Journal of Lasers》1997,6(3):213-222
MultipleEfectiveTwo┐photonCorelated┐emisionOpticalBistabilitywithInjectedSquezedVacuumHUANGHongbina),b)XINGLinglingc)SONGJil... 相似文献
20.
This paper proposes an efficient scheme for deterministic generation
of entangled coherent states for two atomic samples. In the scheme
two collections of atoms are trapped in an optical cavity and driven
by a classical field. Under certain conditions the two atomic
samples evolve from an coherent state to an entangled coherent
state. During the interaction the cavity mode is always in the
vacuum state and the atoms have no probability of being populated in
the excited state. Thus, the scheme is insensitive to both the
cavity decay and atomic spontaneous emission. 相似文献