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1.
C. Ottaviani S. Rebić D. Vitali P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):281-296
The interaction of a five-level atomic system involving electromagnetically induced transparency with four light fields is
investigated.
Two different light-atom configurations are considered, and their efficiency in generating large nonlinear cross-phase shifts
compared.
The dispersive properties of those schemes are analyzed in detail, and the conditions leading to group velocity matching for
two of the light
fields are identified. An analytical
treatment based on amplitude equations is used in order to obtain approximate solutions for the susceptibilities, which are
shown to fit well
with the numerical solution of the full Bloch equations in a large parameter region. 相似文献
2.
N. Vujičić S. Vdović D. Aumiler T. Ban H. Skenderović G. Pichler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):447-454
We present direct observation of the velocity-selective optical pumping of
the Cs ground state hyperfine levels induced by the femtosecond (fs) laser
oscillator centered at either D2 (6 2S1/2↦6 2P3/2,
852 nm) or D1 (6
P1/2, 894 nm) cesium
line. We utilized previously developed modified direct frequency comb
spectroscopy (DFCS) which uses a fixed frequency comb for the excitation and
a weak cw scanning probe laser centered at the 133Cs 6
2S1/2↦6 2P3/2 transition (D2 line) for ground
levels population monitoring. The frequency comb excitation changes the
usual Doppler absorption profile into a specific periodic, comblike
structure. The mechanism of the velocity selective population transfer
between the Cs ground state hyperfine levels induced by fs pulse train
excitation is verified in a theoretical treatment of the multilevel atomic
system subjected to a pulse train resonant field interaction. 相似文献
3.
X.-m. Hu J. Xiong J.-s. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):401-413
A theoretical analysis of the spectral linewidth of V-type inversionless and Raman lasers is presented. First, we examine
the effects of the atomic coherence between dressed states and the Autler-Townes splitting on the linewidth. It is demonstrated
that near above threshold, the V inversionless laser has a narrower linewidth than that of the two-level laser. Instead of
the dressed coherence, it is the Autler-Townes splitting that is responsible for the linewidth reduction though the dressed
coherence determines the laser gain. Next, we explore the effects of the generated laser intensity on the linewidth. It is
shown that the linewidths of the V inversionless and Raman lasers follow the usual 1/I decrease for smaller laser intensity I, but a slower decrease than 1/I for larger laser intensity. For the V Raman laser, even more surprisingly, with the laser intensity increasing, the linewidth
appreciably increases as well. As a result, well above threshold, the V inversionless and Raman lasers may have a larger linewidth
than that of the two-level laser. Finally, a comparison is made between the V lasers and the Λ lasers. It is found that the
linewidth of the Λ inversionless laser shows a fast 1/I
2 decay under optimum conditions.
Received 25 October 1999 and Received in final form 10 March 2000 相似文献
4.
K. Jin Z. C. Wang Q. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):325-332
We study the absorption spectra of a degenerate V-type
atom, where a resonant driving field and a probe field drive
different branches of transitions and a dc field is applied to
drive the transition between two excited states. The effects of
vacuum induced coherence (VIC) on the absorption spectra are
investigated. It is demonstrated that in some special cases the
VIC can lead to the depression of absorption and narrow resonance.
The origin of these features are discussed. When the pump field
and the dc field have the same intensity, it is interesting to
find that the whole absorption spectrum comes mainly from the
absorptions induced by the interferences among different
transitions between dressed states. 相似文献
5.
J. H. Li X. X. Yang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):563-569
We theoretically investigate the features of two-photon absorption
in a five-level atomic system with interacting dark resonances. It
is found that two-photon absorption can be completely suppressed
at two different frequencies due to the application of two
coherent coupling fields and the atomic system exhibits double
electromagnetically induced transparency windows against
two-photon absorption. The position and width of the double
two-photon transparency windows can be controlled via properly
adjusting the frequency detuning and the intensities of the two
coupling fields. In addition, one enhanced narrow central line can
be observed in the two-photon absorption spectra, which may find
applications in high-precision spectroscopy. Form a physical point
of view, we explicitly explain these results in terms of quantum
interference induced by three different two-photon excitation
channels in the dressed-state picture. 相似文献
6.
M. Gartz C. Keutgen S. Kuenneke U. Kreibig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(1):127-131
In this paper a detailed experimental study of Coherent Population Trapping (CPT) effect on sodium induced by a dye-laser
operating in a three-mode regime is presented and a detailed analysis of the role of velocity changing collisions is made.
These collisions show a very small relaxation effect on the dark resonances which are visible even at high pressures. For
the first time we demonstrate the persistence of the ground state coherence to pressures up to one atmosphere for a relatively
“heavy” buffer gas like argon. The experimental results have been compared with theory and a very good agreement has been
obtained. Preliminary results on the effect of Na-N2 collisions on Coherent Population Trapping are presented.
Received: 5 October 1998 / Received in final form: 3 December 1998 相似文献
7.
X.-J. Liu H. Jing M.-L. Ge 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):297-303
We examine in detail the quantum memory technique for photons in a
double Λ atomic ensemble in this work. The novel
application of the present technique to create two different
quantum probe fields as well as entangled states of them is
proposed. A larger zero-degeneracy class besides dark-state
subspace is investigated and the adiabatic condition is confirmed
in the present model. We extend the single-mode quantum memory
technique to the case with multi-mode probe fields, and reveal the
exact pulse matching phenomenon between two quantized pulses in
the present system. 相似文献
8.
9.
G. Huang C. Hang L. Deng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):437-444
We study stable propagation of multiple shape-preserving optical
pulses in an inhomogeneously broadened multi-level atomic medium.
By analytically solving the Maxwell-Schr?dinger equations
governing the evolution of N coupled optical fields and atomic
amplitudes we show that N pulsed optical waves coupling to
(N+1)-levels can be automatically matched with the same soliton
waveform and identical yet very slow propagation velocity. Several
sets of coupled soliton solutions for two different (N+1)-level
models are given and their stability is studied by using a
numerical simulation. 相似文献
10.
J.-H. Wu J.-Y. Gao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):315-319
In order to achieve the phase-sensitive probe gain without population inversion, we investigate a three-level Λ-type atomic system driven by a coherent field and a microwave field. It is shown that, by modulating the relative phase of
applied fields, we can obtain quite high inversionless gain at different probe detunings and change the gain behavior of the
probe correspondingly. We find that amplitudes of the coherent field and the microwave field are also important factors that
can result in different gain behavior of the probe. Here, we use the microwave field to induce the quantum coherence between
the two ground levels, which is necessary for phase-sensitive effects, since it can result in the interference between two
different transition channels.
Received 20 June 2002 / Received in final form 5 December 2002 Published online 4 March 2003 相似文献
11.
Zhuan Li Li-Ping Deng Li-Sen Xu Kaige Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):147-156
We study a four-level double-Λ atomic ensemble interacting with two
time-dependent signal fields and two stationary control fields. Though, in
each Λ channel, a pair of signal and control fields couple
resonantly with the two lower levels of atoms, the occurrences of
electromagnetically induced transparency (EIT) is affected by the coherence
of the four fields. In the discussion of atomic susceptibilities, we show
that the quantum coherence between the two lower levels can be either formed
or released according to the phase matching of the four fields. We analyze
the propagation equation of the two signal fields, and find two
characteristic solutions: the stationary transmission wave and the transient
decay wave. The former corresponds to a correlated EIT effect in which two
signal pulses are shape-matched. The latter is an opposite effect to the
correlated EIT in which two pulses quench simultaneously, thus named as the
correlated two-signal absorption (CTSA). We propose the CTSA condition in
correspondence with the EIT condition. The numerical simulation shows that
the double-Λ configuration is capable of manipulating synchronous
optical signals and thus provides multiplicity and versatility in quantum
information process. 相似文献
12.
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
13.
J. Martin T. Bastin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(2):301-311
The quantum theory of the cold atom micromaser including
the effects of gravity is established in the general case where the
cavity mode and the atomic transition frequencies are detuned. We
show that atoms which classically would not reach the interaction
region are able to emit a photon inside the cavity. The system turns
out to be extremely sensitive to the detuning and in particular to
its sign. A method to solve the equations of motion for non resonant
atom-field interaction and arbitrary cavity modes is presented. 相似文献
14.
A. D. Gazazyan E. A. Gazazyan A. G. Margaryan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):243-251
The possibility of storage of quantum information with photons is studied in the case of resonant transitions via many close
lying exciton levels in a solid with impurity -atoms. The upper levels of the impurity atom form resonant Fano states, similar to the autoionization atomic states, due
to the configuration interaction with the continuum of the exciton band. In this case slowing of light pulses is shown to
be realistic, in the presence of the control field, down to the group velocity much lower than that in vacuum. The possibility
of storage and reconstruction of a quantum pulse is studied in the case of the instantaneous switching on/off of the control
field. It is shown that the signal quantum pulse cannot be stored undistorted for differing values of Fano parameters and
for non-zero two-photon detuning and decay rate between the lower levels (decoherence). However, for small difference of the
Fano parameters and for small values of the two-photon detuning and the decoherence there is no distortion in the case where
the length of the pulse is much longer than the linear absorption (amplification) length, so the shape and quantum state of
the light pulse can be restored. 相似文献
15.
M. M. Hossain S. Mitra S. Chakrabarti D. Bhattacharyya B. Ray P. N. Ghosh 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):141-146
We report the experimental observation of electromagnetically induced transparency (EIT) in a Doppler broadened rubidium vapour
at room temperature for different probe intensities at a fixed pump intensity in a five-level Λ-type system formed by the
D2 transition of 85Rb. For a constant pump intensity, we find that the EIT width and height change with the variation of probe intensity. We
observe a nonlinear variation of the height of the EIT peak and a linear variation of the width (FWHM) of the EIT signal with
probe intensity. In the Doppler broadened multilevel system, we also observe the velocity selective dips along with the EIT
signal. A numerical simulation of the probe response signal based on density matrix representation in a five-level system
is carried out to reproduce the experimentally observed spectra. 相似文献
16.
X. J. Fan A. Y. Li S. F. Tian D. M. Tong S. Q. Gong Z. Z. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):483-488
We studied effects of the relative phase between the probe and driving fields on the absorption and dispersion properties
in an open three-level ladder system with spontaneously generated coherence but without incoherent pumping. It is shown that
by the phase controlling, switching from absorption to lasing without inversion (LWI) and enhancing remarkablely LWI
gain can be realized; large index of refraction with zero absorption and the
electromagnetically induced transparency can be obtained. We also find that
varying the atomic injection and exit rates has a considerable influence on
the phase dependent-absorption property of the probe field, existent of the
atomic injection and exit rates gives the necessary condition of the
realization of LWI, getting LWI is impossible in the corresponding closed
system without incoherent pumping. 相似文献
17.
F. Casagrande A. Lulli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):165-172
We investigate the entanglement of an open tripartite
system where a cavity field mode in thermal equilibrium is
off-resonantly coupled with two atoms that are simultaneously driven
by a resonant coherent field. For moderately detuned atom-field
coupling and strong atomic driving we show the generation, at given
interaction times and for low enough cavity decay rates, of atomic
Bell states and of Bell state superpositions relevant for quantum
gates implementation. The system can oscillate between bi-separable
and fully separable states. Also we describe the distribution of
quantum correlations between the atom-atom and the two atom-field
subsystems. In the dispersive coupling regime with strongly driven
atoms we show the generation of nearly stationary Bell states which
remain protected from cavity dissipation. 相似文献
18.
K. I. Osman S. S. Hassan A. Joshi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(1):119-130
The effects of spontaneously generated coherence (SGC) and phases of
optical fields on the phenomenon of electromagnetically induced
transparency (EIT) are investigated in a four-level inverted-Y
system and in a five-level K-type system under various parametric
conditions in order to demonstrate controllability of the EIT,
dispersion properties, and group velocity in such systems. Non-zero
second-order susceptibility in both systems is due to the SGC
effect. The experimental viability of the model in semiconductor
quantum well systems is also discussed. 相似文献
19.
Q. Xu X. M. Hu J. W. Yin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(2):267-273
The atomic coherence in a three-level Λ atom is studied, in which each optical transition is driven by a coherent field and
the metastable states are coupled to each other via a microwave field. It’s shown that the atomic coherence crucially depends
on the relative phase delay between the envelopes of the amplitudes of the three coupling fields. In particular, when the
phase delay is adjusted to 0 or π, the maximal atomic coherence arises, while the maximal atomic coherence doesn’t occur once
the phase delay is changed to π/2. The maximal atomic coherence is attributed to the trapping of the population in the lower
sublevels. 相似文献
20.
H.-F. Zhang J.-H. Wu J.-Y. Gao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):443-447
A five-level system to control the wavelength of the in-line amplifier by the quantum interference is proposed. It is found
that the gains of the first and the second probe can be adjusted by changing the coherent field and the incoherent pumping.
The new scheme may find its application in optical switch and optical communications.
Received 9 October 2002 Published online 24 April 2003
RID="a"
ID="a"e-mail: qol@mail.jlu.edu.cn 相似文献