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1.
Cavity-Induced Enhancement of Squeezing in Resonance Fluorescence of a V-Type Three-Level Atom
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The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field exhibit squeezing in the out-of-phase quadrature. The coupling between the atom and the cavity mode can greatly enhance the squeezing centred at the laser frequency. More importantly, for strong excitation, under the effect of the cavity-atom coupling, the in-phase quadrature of fluorescence can exhibit two-mode squeezing at the two inner sideband frequencies. By working in the dressed-state representation and hiring secular approximation, we give an analytical explanation for the effect. The result shows, under appropriate conditions, the squeezing can be greatly enhanced by appropriately tuning the cavity resonant frequency. 相似文献
2.
M. Gangl H. Ritsch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):29-40
We develop quantum models for the combined external and internal motion of atoms in a strongly coupled driven cavity mode
including the transverse degrees of freedom. Using a simplified Gaussian mode function we determine the parameter regimes
and prospects of 3D cooling and confinement of one or two atoms in the cavity field. Analysing the field dynamics for slow
atoms traversing the cavity, we show that the spectrum of the transmitted and spontaneously scattered light contains ample
information on the motional dynamics of the atom and can be nicely used to investigate the cooling properties of the system.
Including several atoms in the dynamics we show how motional correlations build up by the common interaction with the cavity
field. This can be looked upon as collisions at far distance and can be monitored via the transmitted field dynamics.
Received 5 March 1999 and Received in final form 4 May 1999 相似文献
3.
We have studied the spontaneous emission behaviour in a five-level M-type atom driven by two optical fields of high frequencies and a microwave field of low-frequency. In absence of non-orthogonal decaying pathways, due to microwave field induced low-frequency coherence, the present model produces the emission spectrum resembling that of a three-level system controlled by the effect of vacuum induced decay-interference. For particular sets of values of the Rabi frequencies of the resonant coherent fields, the system exhibits quantum interference induced switching effect. By using this model, we have shown that the phenomenon of narrowing can be induced in the emission peaks without any detuning and phase control of the coherent fields. With the increase in the value of the Rabi frequency of the microwave field, this feature will be accompanied by the peak-compression and -repulsion effect. When the coherent fields are far from resonance, the appearance of the single-photon and the two-photon peaks in the emission spectrum can be easily controlled by changing the value of the Rabi frequency of the microwave field. We have shown the appearance of multiple dark regions in the emission line shape for equal as well as unequal decay rates of two emission pathways. Other interesting phenomena like elimination, enhancement and suppression of spectral line are also explored in various resonant and non-resonant cases. 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.
Ch. Andreeva G. Bevilacqua V. Biancalana S. Cartaleva Y. Dancheva T. Karaulanov C. Marinelli E. Mariotti L. Moi 《Applied physics. B, Lasers and optics》2003,76(6):667-675
We investigate the coherent population trapping effect occurring between the Zeeman sublevels of a given hyperfine state of
Cs when excited by a single-mode diode laser, which is frequency modulated in the kHz–MHz range. In the presence of a dc magnetic
field, simultaneous excitation of pairs of ground-state magnetic sublevels to common excited magnetic sublevels is performed.
As a result, coherent population trapping resonance is detected at only a given modulation frequency, whose value gives a
measure of the magnetic field. The parameters of the resonances are measured in order to determine the ultimate accuracy of
the magnetic field measurement.
Received: 6 December 2002 / Revised version: 24 February 2003 / Published online: 2 June 2003
RID="*"
ID="*"Corresponding author. Fax: +39-0577/23-4689, E-mail: biancalana@unisi.it 相似文献
6.
L. Vernac M. Pinard V. Josse E. Giacobino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):129-135
Using a quantum theory for an ensemble of two- or three-level atoms driven by electromagnetic fields in an optical cavity,
we show that the various spins associated with the atomic ensemble can be squeezed. Two kinds of squeezing are obtained: on
the one hand self-spin squeezing when the input fields are coherent ones and the atomic ensemble exhibits a large non-linearity;
on the other hand squeezing transfer when one of the incoming fields is squeezed.
Received 14 August 2001 and Received in final form 7 November 2001 相似文献
7.
Q. Xu J. W. Yin X. M. Hu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(2):271-276
It's shown that the incoherent fluorescence spectrum from a three-level
Λ atom with orthogonal atomic transition dipole moments is comprised
of a single ultrasharp line by simulating the vacuum-induced coherence
(VIC), and the line is on resonance with the driving field. The physical
interpretation of the spectral characteristics is given in terms of dressed states. 相似文献
8.
The transient gain property of a weak probe field in an asymmetric semiconductor coupled double quantum well structure is reported. The transient process of the system, which is induced by the external coherent coupling field, shows the property of no inverse gain. We find that the transient behavior of the probe field can be tuned by the change of tunneling barrier. Both the amplitude of the transient gain and the frequency of the oscillation can be affected by the lifetime broadening. 相似文献
9.
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
10.
We reveal that for a realistic system, interference effects are obtained such as the suppression of central line and inner sidebands and the narrowing of the outer fluorescence sidebands. For this purpose, we consider a spontaneous decay from an excited state to a metastable state when the excited and metastable states are resonantly coupled to an auxiliary metastable state by a laser field and a microwave field, respectively. The fluorescence spectrum evolves from a five-peaked structure into a doublet of ultrasharp lines as the ratio of the laser field Rabi frequency to the microwave Rabi frequency is decreased. The physical origin is presented in terms of dressed states. 相似文献
11.
A. Godone F. Levi S. Micalizio J. Vanier 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):5-13
An analysis of the phenomenon of coherent population trapping as observed by means of the dark state in the case of optically
thick vapors in alkali metal atoms is presented. Very different behaviors are predicted for the observation of the dark state
in the fluorescence and transmission spectra of the same atomic sample when the optical length is not negligible. Among other
effects, the dark line observed in the fluorescence signal may look inverted appearing as a bright line, while in the transmission
signal a narrowing of the line width resonance line is observed for an increase of the atomic density. In the pure three-level
scheme a subnatural width is predicted. These effects, related to the electromagnetically induced transparency phenomenon,
are readily observed in experiments, which are found to be in excellent agreement with the theory developed.
Received 28 March 2001 and Received in final form 3 October 2001 相似文献
12.
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
13.
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
14.
C. Mavroyannis 《Applied physics. B, Lasers and optics》2001,73(1):39-50
We have considered the interference spectra that occur at the three-photon generated frequency arising from the interaction
of three laser fields with a four-level atom, where two of the laser fields are on two-photon resonance with the three levels
forming a “λ” scheme while the third laser operates between the second ground and the second excited state of the atom. At
low intensities of all three laser fields, the overall intensity of the peak at the three-photon generated frequency, describing
the spectrum of an electron in the second excited state, depends on the strength of the combined field of the two laser fields
that are on two-photon resonance and it takes negative values. This indicates that light amplification without population
inversion is likely to occur at the three-photon generated frequency. The combined field of the three laser fields induces
multiphoton excitations near the three-photon generated frequency, whose peaks are characterized by linewidths which are much
less than the natural linewidths of the atoms. These excitations describe absorption or stimulating emission processes depending
on the values of the detunings of the laser fields. The derived results are graphically presented and discussed.
Received: 24 January 2001 / Published online: 8 June 2001 相似文献
15.
F. Grosshans P. Grangier 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):119-125
Homodyne detection can be used to perform measurements on various quantum states of the light, such as conditional single
photon states produced by parametric fluorescence processes. In the pulsed regime, the time and frequency overlap between
the single photon wave packet and the local oscillator field plays a crucial role. We show in this paper that this overlap
can be characterized by an effective quantum efficiency, which is explicitly calculated in various situations of experimental
interest.
Received 27 July 2000 and Received in final form 29 November 2000 相似文献
16.
C. Affolderbach A. Nagel S. Knappe C. Jung D. Wiedenmann R. Wynands 《Applied physics. B, Lasers and optics》2000,70(3):407-413
We have evaluated the suitability of a vertical-cavity surface-emitting laser diode (VCSEL) for spectroscopic applications.
Despite its low output power it is possible to observe narrow resonances in a saturated absorption spectroscopy experiment
on the cesium D
2 transition at 852 nm, limited in width by the laser linewidth of several tens of MHz. High modulation efficiency of the VCSEL
allows us to create modulation sidebands at 9.2 GHz frequency via direct modulation of the laser injection current. Using
the carrier and either one of the sidebands coherent population trapping (CPT) resonances in a buffered cesium vapor can be
prepared with linewidths below 130 Hz. With this very compact setup we have studied the dependence of CPT resonance position
and linewidth as a function of optical detuning and find evidence of the influence of the excited state hyperfine structure.
Received: 30 April 1999 / Revised version: 25 June 1999 / Published online: 30 November 1999 相似文献
17.
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
18.
H.P. Breuer B. Kappler F. Petruccione 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):9-13
A fast simulation algorithm for the calculation of multitime correlation functions of open quantum systems is presented. It
is demonstrated that any stochastic process which “unravels” the quantum Master equation can be used for the calculation of
matrix elements of reduced Heisenberg picture operators, and thus for the calculation of multitime correlation functions,
by extending the stochastic process to a doubled Hilbert space. The numerical performance of the stochastic simulation algorithm
is investigated by means of a standard example.
Received: 30 May 1997 / Revised: 4 November 1997 / Accepted: 7 November 1997 相似文献
19.
We propose a new scheme for realizing left-handed electromagnetic properties in a coherently driven four-level system. At the presence of spontaneously generated coherence and the local field effect, both dielectric permittivity and magnetic permeability may have negative real parts of the same order in a small frequency band. Thus, one can achieve the negative refractive index and then manipulate it by modulating the coherent field or changing the atomic density. With incoherent pumping applied to have more remarkable spontaneously generated coherence, one can further obtain a wider frequency band of negative refraction and simultaneously reduce the accompanied absorption. 相似文献
20.
Z. Ficek J. Seke A.V. Soldatov G. Adam N.N. Bogolubov Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):411-419
We investigate the absorption and dispersion properties of a two-level atom driven by a polychromatic field. The driving field
is composed of a strong resonant (carrier) frequency component and a large number of symmetrically detuned sideband fields
(modulators). A rapid increase in the absorption at the central frequency and the collapse of the response of the system from
multiple frequencies to a single frequency are predicted to occur when the Rabi frequency of the modulating fields is equal
to the Rabi frequency of the carrier field. These are manifestations of the undressing or a disentanglement of the atomic
and driving field states, that leads to a collapse of the atom to its ground state. Our calculation permits consideration
of the question of the undressing of the driven atom by a multiple-modulated field and the predicted spectra offer a method
of observing undressing. Moreover, we find that the absorption and dispersion spectra split into multiplets whose structures
depend on the Rabi frequency of the modulating fields. The spectral features can jump between different resonance frequencies
by changing the Rabi frequency of the modulating fields or their initial phases, which can have potential applications as
a quantum frequency filter.
Received 23 October 2001 and Received in final form 31 January 2002 相似文献