共查询到20条相似文献,搜索用时 15 毫秒
1.
D. G. Han Y. G. Zeng H. Guo W. Chen H. Lu C. Huang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):489-493
Driven by one upper level coupling field, a three-level
V-type atomic system with a pair of upper levels is studied. With
one strong coupling field and one weak probe field, it is found
that, due to the effects of the upper level coupling field, the
quantum coherence between the two upper levels can be induced, and
the absorption of the probing field is very sensitive to the
relative phase of the probe, the pumping and the upper level
coupling fields. With proper parameters, lasing without inversion
(LWI) can be realized. 相似文献
2.
M. Al-Amri M. Babiker 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):417-421
We explain why a system of cold 85Rb atoms at temperatures of the order T≈ 7.78× 10-5 K
and below, but not too low to lie in the quantum reflection regime, should be automatically repelled from
the surface of a conductor without the need of an evanescent field, as in a typical atom mirror, to counteract the van
der Waals attraction. The
repulsive potential arises naturally outside the conductor and is effective at distances from the
conductor surface of about 400 nm, intermediate between
the van der Waals and the Casimir-Polder regions of variation. We propose that such a field-free reflection capability should
be useful
as a component in cold atom traps.
It should be practically free of undesirable field
fluctuations and would be operative at distances for which surface roughness, dissipative effects and other finite conductivity
effects should be negligibly small. 相似文献
3.
J. P. Xu Y. P. Yang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):135-145
Recently, Liu et al. [Phys. Rev. B 74, 075314 (2006)] pointed out that the atomic instant decay rate in one dimensional photonic crystal (1DPC) showed a series
of pulse-like peaks with time. In this paper, we continue their work, and adopt a special 1DPC, in which the refractive indexes
of both constitution layers in a period are the same, to perform the analysis in detail. Our results show that the pulse-like
peak of instant decay rate originates from the interaction between the atom and the sub-reservoir, the latter of which corresponds
to the group of reflected fields having the same optical distance. The atom interacts with such a sub-reservoir mainly after
the time needed for propagation. However, near the arrival time of the reflected field, the atomic level is broadened and
couples to all frequency components of the sub-reservoir, and the pulse-like peak of instant decay rate appears. Although
our conclusion is deduced with the special 1DPC, it is also valid for more general cases and might be useful to measure the
quantum Zeno and anti-Zeno effect, since the interval of repeated measurements may be expanded to several optical cycles in
1DPC, which will facilitate the observation of the quantum Zeno or anti-Zeno effect. 相似文献
4.
V.I. Yukalov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):83-91
An ensemble of resonance atoms is considered, which are doped into a medium with well developed polariton effect, when in
the spectrum of polariton states there is a band gap. If an atom with a resonance frequency inside the polariton gap is placed
into the medium, the atomic spontaneous emission is suppressed. However, a system of resonance atoms inside the polariton
gap can radiate when their coherent interaction is sufficiently strong. Thus the suppression of spontaneous emission for a
single atom can be overcome by a collective of atoms radiating coherently. Conditions when such collective effects can appear
and their dynamics are analysed.
Received 7 June 2000 相似文献
5.
J. H. Li 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):467-473
We theoretically study the features of the spontaneous emission
spectra in a coherently driven cold four-level atomic system with
a cyclic configuration. It is shown that a few interesting
phenomena such as spectral-line narrowing, spectral-line
enhancement, and spectral-line suppression can be realized in our
system. Interestingly enough, the spectral-line enhancement and
suppression can be controlled just by appropriately modulating the
phase, the frequency, and the intensity of an external coherent
magnetic field, respectively. This investigation may find
applications in high-precision spectroscopy.
An erratum to this article is available at . 相似文献
6.
S. Yuan J.-Y. Gao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):267-272
A new scheme of the influence of quantum interference on the spontaneous emission in a coherently driven three-level medium
is presented in this paper. The results are the same with that discussed by [S.-Y. Zhu, L.M. Narducci, M.O. Scully, Phys.
Rev. A 52, 4791 (1995)] under resonance conditions, but they are different when the driven field is detuned.
Received 8 September 1999 and Received in final form 13 January 2000 相似文献
7.
8.
Q. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):387-392
The effects of the non-rotating wave approximation (non-RWA) on the
spontaneous emission of a V-type three-level atom are studied, where the
excited states are coupled to a common ground state by a weak laser field
and the upper-level doublet is driven by a strong microwave field. When the
non-RWA is applied to the interaction of the atom with the microwave field,
for some values of the parameters involved, the spontaneous emission
spectrum is comprised of a central peak and a series of sidebands with a
constant spacing of the microwave frequency, and the central peak and/or
sidebands can be split into two components. The physical interpretation of
the spectral characteristics is given in light of the dressed states. 相似文献
9.
G. H. Yang L. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(2):277-282
We investigate two identical Λ-type atoms in free space, and focus
on the entanglement between the two atoms. We derive a master equation for
the atomic subspace and solve it analytically to show how the spontaneous
emission from the two atoms system induces entanglement. The magnitude of
the entanglement and the steady state entanglement are found to be strongly
dependent on the initial states and the orientation of the dipoles of the
two atoms. 相似文献
10.
W. -S. Dai M. Xie 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):125-128
The electromagnetic transition of two-level atomic systems in a waveguide is calculated. Compared with the result in free
space, the spontaneous emission rate decrease because the phase space is smaller, and meanwhile, some resonance appears in
some cases. Moreover, the influence of non-uniform electromagnetic field in a waveguide on absorption and stimulated emission
is considered. Applying the results to lasers, a method to enhance the laser power is proposed.
Received 29 May 2001 and Received in final form 25 October 2001 相似文献
11.
Q. X. Mu Y. H. Ma L. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):375-379
We present a method of generating two-mode single atom
laser based on the nonresonant interaction of a three-level
Λ type atom in a two-mode cavity with three strong classical
driving fields. An analytical solution for this effective dynamics
under the presence of the cavity losses is obtained, which allow us
to analyze the entanglement properties and the photon statistics of
the two cavity modes exactly. It is also shown that the possible
generation of the two-mode entangled coherent states in the
transient regime after the atomic measurement. 相似文献
12.
13.
C. Russo H. G. Barros A. Stute F. Dubin E. S. Phillips T. Monz T. E. Northup C. Becher T. Salzburger H. Ritsch P. O. Schmidt R. Blatt 《Applied physics. B, Lasers and optics》2009,95(2):205-212
We describe an ion-based cavity-QED system in which the internal dynamics of an atom is coupled to the modes of an optical
cavity by vacuum-stimulated Raman transitions. We observe Raman spectra for different excitation polarizations and find quantitative
agreement with theoretical simulations. Residual motion of the ion introduces motional sidebands in the Raman spectrum and
leads to ion delocalization. The system offers prospects for cavity-assisted resolved-sideband ground-state cooling and coherent
manipulation of ions and photons.
C. Russo and H.G. Barros contributed equally to this work. 相似文献
14.
V. Hannstein G. C. Hegerfeldt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):415-422
A simplified scheme for the investigation of cooperative effects in
the quantum jump statistics of small numbers of fluorescing atoms
and ions in a trap is
presented. It allows the analytic treatment of three
dipole-dipole interacting four-level systems which model the
relevant level scheme of Ba+ ions. For the latter, a huge rate of
double and triple jumps was reported in a former experiment and the
huge rate was attributed to the dipole-dipole interaction. Our theoretical
results show that the effect of the dipole-dipole interaction on these rates
is at most 5% and that for
the parameter values of the experiment there is practically no
effect. Consequently it seems that the
dipole-dipole interaction can be ruled out as a possible explanation for
the huge rates reported in the experiment. 相似文献
15.
H. Kayhan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):443-449
The entanglement dynamics in a system of the
interaction of an atom with a single-mode thermal field in the
presence of noise is studied by the Jaynes-Cummings model.
Two-state random phase telegraph noise is considered as the noise
in the interaction and an exact solution to the model under this
noise is obtained by the Burshtein equation. Although the
Burshtein equation is applicable for laser-atom interactions, it
is shown that it can be applied to atom-thermal field system as a
special case. The solution is used to investigate the entanglement
dynamics of the atom-field interaction by calculating a lower
bound on concurrence. It is found that the entanglement is a non
monotonic function of the intensity of the noise. The degree of
the entanglement decreases to a minimum value for an optimal
intensity of the noise and then increases for a sufficiently large
intensity. Moreover, intense noise may generate stronger
entanglement compared with the absence of noise. 相似文献
16.
F. Plastina F. Piperno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(3):407-413
We examine the decay dynamics of a free four-level system in the -V configuration. Quantum interference strongly manifests itself in this system, as can be seen by looking at the combined spectral
distribution of the two emitted photons and at the time evolution of the intermediate-level populations, whose effective lifetimes
can become very long under certain conditions for the atomic parameters. This effect is attributable to a population transfer
mechanism induced in the time evolution equations by the Fano terms, also responsible for the strong modifications of the
spectral correlation between the emitted photons which we analyze in detail. Finally, population trapping can also occur when
the two intermediate levels are degenerate.
Received: 20 October 1998 相似文献
17.
W. Y. Liang J. W. Dong G. Q. Liang H. Z. Wang 《Applied physics. B, Lasers and optics》2009,96(4):781-785
We study the collimated emission characteristics from a dipole source inside a negative-effective-refractive-index photonic
crystal with a quasi-cavity constructed by a concave photonic crystal reflector. The emissions along the ±X and −Y directions are forbidden by the quasi-cavity, so that most emissions propagate along the +Y direction. Simulation results show that a narrow collimated beam is achieved due to the near-zero negative effective refractive
index. Moreover, the half-power beam width of such a collimated beam can be reduced to 3.48° by optimizing the size of the
source area. Such a compact structure would have potential applications in micro-optical devices. 相似文献
18.
The photoluminescence correlation from a single CdSe nanocrystal under pulsed excitation is studied, and a single photon is
realized at wavelength 655 nm at room temperature. The single colloidal CdSe quantum dot is prepared on a SiO2/silicon surface by a drop-and-drag technique. The long-term stability of the single-photon source is investigated; it is
found that the antibunching effect weakens with excitation time, and the reason for the weakening is attributed to photobleaching.
The lifetimes of photoluminescence from a single quantum dot are analyzed at different excitation times. By analyzing the
probability distribution of on and off times of photoluminescence, the Auger assisted tunneling and Auger assisted photobleaching models are applied to explain
the antibunching phenomenon. 相似文献
19.
C.-Q. Cao C.-G. Yu H. Cao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):279-284
The spontaneous emission of an excited atom is analyzed by quantum stochastic trajectory approach without both rotating-wave
approximation and Markovian approximation. The atom finite size effect is also taken into account. We show by an example that
the correction due to the counter-rotating wave term is rather small, even for the largest atomic number of real nuclei.
Received 10 July 2002 / Received in final form 12 November 2002 Published online 4 February 2003 相似文献
20.
The well-known spatially distributed form of the near field, associated with a dipolar source, is usually unsuitable for effecting
the excitation of a location-specific detector in the vicinity. It is of interest, therefore, to identify a means of producing
a much more greatly directed character to such a near field, imposing features that are more commonly associated with longer-range,
wave-zone electromagnetic propagation. In this paper, it is shown that nonlinear optical coupling with off-resonant, throughput
laser light can achieve this effect. Based on a quantum electrodynamical analysis it is shown that two mechanisms contribute;
one requires both the source and detector to be irradiated by the throughput radiation, the other can operate with the source
alone irradiated. The analysis leads to results identifying the dependence of each mechanism on the relative directions of
the laser beam and the source–detector displacement. Contour maps of the ensuing near field, at the source emission frequency,
exhibit a directionality that grows with the off-resonant beam intensity. The phenomenon affords a means of achieving optical
control over the near-field distribution. 相似文献