共查询到20条相似文献,搜索用时 15 毫秒
1.
P. Domokos T. Kiss J. Janszky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):49-53
A beam of diatomic molecules scattered off a standing wave laser mode splits according to the rovibrational quantum state
of the molecules. Our numerical calculation shows that single state resolution can be achieved by properly tuned, monochromatic
light. The proposed scheme allows for selecting non-vibrating and non-rotating molecules from a thermal beam, implementing
a laser Maxwell's demon to prepare a rovibrationally cold molecular ensemble.
Received 23 August 2000 and Received in final form 17 November 2000 相似文献
2.
J. S. Bakos G. P. Djotyan P. N. Ignácz M. Á. Kedves M. Serényi Zs. Sörlei J. Szigeti Z. Tóth 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):141-149
The displacement of Rb atoms in a magneto-optical trap (MOT) caused by the force of a finite time series of counter-propagating
frequency modulated light pulse pairs is measured as a function of the chirp of the pulses. The frequency modulated light
pulses induced 85Rb 52S1/2 F=3 ↔ 85Rb 52P3/2 F'=2, 3, 4 excitation and de-excitation of the atoms. The result of this excitation
de-excitation process is a force causing the acceleration and, consequently, the displacement of the maximum of the spatial
distribution of the trap atoms. The time dependence of the populations of the levels of the atom are calculated — including
also the 85Rb 52S1/2 F=2 and F'=1 states — as
the result of the interaction with the finite train of counter propagating frequency modulated light pulses by the solution
of the Bloch equations. As the result of the measurement the interval of the chirp of the frequency modulated light of given
intensity where the transitions take place, are determined. The results of the experiment and the expectation on the basis
of model calculations are in qualitative agreement. 相似文献
3.
An atom faucet 总被引:3,自引:0,他引:3
W. Wohlleben F. Chevy K. Madison J. Dalibard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):237-244
We present a simple and efficient source of slow atoms. From a background vapour loaded magneto-optical trap (MOT), a thin
laser beam extracts a continuous jet of cold rubidium atoms. The jet that is typical to leaking MOT systems is created without
any optical parts placed inside the vacuum chamber. We also present a simple three dimensional numerical simulation of the
atomic motion in the presence of these multiple saturating laser fields combined with the inhomogeneous magnetic field of
the MOT. At a pressure of P
Rb87 = 10-8 mbar and with a moderate laser power of 10 mW per beam, we generate a flux Φ = 1.3×108 atoms/s with a mean velocity of 14 m/s and a divergence of 10 mrad.
Received 13 January 2001 相似文献
4.
J. S. Bakos G. P. Djotyan P. N. Ignácz M. Á. Kedves M. Serényi Zs. Sörlei J. Szigeti Z. Tóth 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(1):59-66
The spatial displacement of the 85Rb atoms in a
Magneto-Optical Trap (MOT) under the influence of series of frequency
modulated light pulse pairs propagating opposite to each other is measured
as a function of the time elapsed after the start of the pulse train, and
compared with the results of simulations. Adiabatic excitation and
consecutive de-excitation take place between the ground
52S1/2 (F=3) and the 52P3/2 (F'=2, 3, 4) excited levels as the result of
the interaction. The displacement of the 85Rb atoms is calculated as
the solution of simple equation of motion where the expelling force is that
arising from the action of the frequency modulated light pulses. The
restoring and friction forces of the MOT are taken into account also. The
system of Bloch equations for the density matrix elements is solved
numerically for transitions between six working hyperfine levels of the atom
interacting with the sequence of the frequency modulated laser pulses.
According to these simulations, the momentum transferred by one pulse pair
is always smaller than the expected 2ħk, (1) where ħ is the Plank constant and
k=2π/λ where λ is the wavelength, (2) having a maximum
value in a restricted region of variation of the laser pulse peak intensity
and the chirp. 相似文献
5.
Reflection of thermal atoms by a pulsed standing wave 总被引:1,自引:0,他引:1
P. Ryytty M. Kaivola 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(3):415-423
Reflection of thermal atoms by a pulsed standing wave with a duration in the nanosecond range is studied. The momentum distribution
of the reflected atoms is determined by calculations based on the adiabatic atom-photon interactions. It is shown that with
a proper choice of the field intensity and the pulse duration the standing-wave pattern functions as a row of independent
atom mirrors. At an optimum choice of the parameter values, the fraction of the elastically reflected atoms is more than 20%.
Furthermore, we show that the pulsed standing-wave mirror can be used to manipulate their final momentum distribution. When
using laser pulses with an intensity of several tens of MW/cm2, tens of thousands of atoms can be reflected by a single laser pulse.
Received 3 December 1999 and Received in final form 25 April 2000 相似文献
6.
P. Ryytty M. Kaivola C.G. Aminoff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):369-372
We study the deflection of sodium atoms by a resonantly tuned pulsed standing wave of high field intensity. The effects of
the phase fluctuations of the pulsed laser field on the momentum distribution of the deflected atoms are experimentally determined.
The results are explained using a theoretical model based on the generalized density matrix formalism of two-level atoms.
Received 23 November 1998 and Received in final form 27 January 1999 相似文献
7.
B. Rohwedder 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):255-260
Fringe shapes in a multiple-beam de Broglie-wave interferometer based on the atomic Kapitza-Dirac effect are studied. An all-optical
implementation of such a device is proposed. A realization in the time-domain, using Bose-Einstein condensates released from
a trap, seems viable within the present state of the art.
Received 5 April 2000 and Received in final form 14 July 2000 相似文献
8.
C.H. Raymond Ooi K.-P. Marzlin J. Audretsch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(2):259-267
A general scheme for reducing the center-of-mass entropy is proposed. It is based on the repetition of a cycle, composed of
three concepts: velocity selection, deceleration and irreversible accumulation. Well-known laser techniques are used to represent
these concepts: Raman π-pulse for velocity selection, STIRAP for deceleration, and a single spontaneous emission for irreversible
accumulation. No closed pumping cycle nor repeated spontaneous emissions are required, so the scheme is applicable to cool
a molecular gas. The quantum dynamics are analytically modelled using the density matrix. It is shown that during the coherent
processes the gas is translationally cooled. The internal states serve as an entropy sink, in addition to spontaneous emission.
This scheme provides new possibilities to translationally laser-cool molecules for high precision molecular spectroscopy and
interferometry.
Received 25 June 2002 / Received in final form 28 September 2002 Published online 12 November 2002
RID="a"
ID="a"e-mail: ooi@spock.physik.uni-konstanz.de
RID="b"
ID="b"e-mail: Peter.Marzlin@uni-konstanz.de
RID="c"
ID="c"e-mail: Juergen.Audretsch@uni-konstanz.de 相似文献
9.
V.S. Malinovsky J.L. Krause 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(2):147-155
We present a general theory of adiabatic rapid passage (ARP) with intense, linearly chirped laser pulses. For pulses with
a Gaussian profile and a fixed bandwidth, we derive a rigorous formula for the maximum temporal chirp rate that can be sustained
by the pulse. A modified Landau-Zener formula displays clearly the relationships among the pulse parameters. This formula
is used to derive the optimal conditions for efficient, robust population transfer. As illustrations of the theory, we present
results for two- and four-level systems, and selective vibronic excitation in the I2 molecule. We demonstrate that population transfer with chirped pulses is more robust and more selective than population transfer
with transform-limited pulses.
Received 6 September 2000 and Received in final form 25 September 2000 相似文献
10.
Single-beam optical bottle for cold atoms using a conical lens 总被引:2,自引:0,他引:2
L. Cacciapuoti M. de Angelis G. Pierattini G.M. Tino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):373-376
We report a new method to generate an optical dipole potential with a null intensity region surrounded in all directions by
light walls. This is achieved with a simple scheme based on a conical lens. Applications to optical trapping of neutral atoms
are discussed.
Received 4 September 2000 and Received in final form 21 January 2001 相似文献
11.
G. Duchateau E. Cormier R. Gayet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):191-196
A simple theoretical approach based on Coulomb-Volkov states is introduced to predict ionisation of atoms by intense laser
pulses in cases where the effective interaction time does not exceed one or two optical cycles [M. Nisoli et al., Opt. Lett. 22, 522 (1997)]. Under these conditions, the energy distributions of ejected electrons predicted by this non-perturbative approach
are in very good agreement with “exact" results obtained by a full numerical treatment. The agreement is all the better that
the principal quantum number of the initial state is high. For very strong fields, most electrons are ejected at an energy
which is close to the classical kinetic energy that would be transferred to free electrons by the electromagnetic field during
the pulse. The power of the present approach appears when keV. In this region, full numerical treatments become very lengthy and finally do not converge. However, the present Coulomb-Volkov
theory still makes reliable predictions in very short computer times.
Received 19 November 1999 and Received in final form 19 January 2000 相似文献
12.
C. Caraby L. Adoui J.P. Grandin A. Cassimi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(1):53-56
We report the observation of resonances in the intensity correlation spectra of a 3D rubidium optical lattice, which we attribute
to light scattering from propagating atomic density fluctuations in the lattice. This process is the spontaneous analog of
the stimulated scattering mechanism recently described by Courtois et al.. We investigate the dependence of the new resonances on the lattice angle and show that they disappear for large angles,
thus resolving previous discrepancies on the subject.
Received: 30 January 1997 / Accepted: 9 October 1997 相似文献
13.
D. Lucas P. Horak G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):261-267
We study one-dimensional Sisyphus cooling on the transition of
87
Rb atoms in the electric field created by two counter-propagating linearly polarized laser beams with an angle of between the polarization directions. The neighbouring F
'=0 and F
'=2 excited states are found to play an important role in the cooling mechanism, e.g., by inhibiting a significant population of the velocity-selective dark state. Our experimental data, such as temperatures
and probe absorption coefficients, agree well with the results of quantum Monte-Carlo wavefunction simulations.
Received 26 November 1998 and Received in final form 20 April 1999 相似文献
14.
L. Sanchez-Palencia P. Horak G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):353-364
We numerically study the spatial diffusion of an atomic cloud experiencing Sisyphus cooling in a three-dimensional linlin optical lattice in a broad range of lattice parameters. In particular, we investigate the dependence on the size of the
lattice sites which changes with the angle between the laser beams. We show that the steady-state temperature is largely independent
of the lattice angle, but that the spatial diffusion changes significantly. It is shown that the numerical results fulfill
the Einstein relations of Brownian motion in the jumping regime as well as in the oscillating regime. We finally derive an
effective Brownian motion model from first principles which gives good agreement with the simulations.
Received 8 August 2001 and Received in final form 6 November 2001 相似文献
15.
A continuous cold atomic beam from a magneto-optical trap 总被引:3,自引:0,他引:3
L. Cacciapuoti A. Castrillo M. de Angelis G.M. Tino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):245-249
We have developed and characterized a new method to produce a continuous beam of cold atoms from a standard vapour-cell magneto-optical
trap (MOT). The experimental apparatus is very simple. Using a single laser beam it is possible to hollow out in the source
MOT a direction of unbalanced radiation pressure along which cold atoms can be accelerated out of the trap. The transverse
cooling process that takes place during the extraction reduces the beam divergence. The atomic beam is used to load a magneto-optical
trap operating in an ultra-high vacuum environment. At a vapour pressure of 10-8mbar in the loading cell, we have produced a continuous flux of 7×107atoms/s at the recapture cell with a mean velocity of 14 m/s. A comparison of this method with a pulsed transfer scheme is
presented.
Received 19 February 2001 相似文献
16.
I. Josopait L. Dobrek L. Santos A. Sanpera M. Lewenstein 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):385-391
The atom optics of Bose-Einstein condensates containing a vortex of circulation one is discussed. We first analyze in detail
the reflection of such a condensate falling on an atomic mirror. In a second part, we consider a rotating condensate in the
case of attractive interactions. We show that for sufficiently large nonlinearity the rotational symmetry of the rotating
condensate is broken.
Received 16 September 2002 / Received in final form 17 November 2002 Published online 11 February 2003 相似文献
17.
A. Lindner H. Freese G. Quehl D. Reiß K. Schiller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):99-112
The time evolution of a damped two-level atom coupled to a damped field mode at resonance is calculated analytically as well
as numerically in the basis of dressed states. We study the dynamics of the density matrix and of observables, e.g. the number of field quanta. For the initial states we consider the field to be in a Fock or Glauber state and the atom in
the ground or excited state. We show the significant influence of the damping on the well-known phenomena of this model, e.g. collapse and revival.
Received 22 January 2001 and Received in final form 16 May 2001 相似文献
18.
J. Eschner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):341-345
Taking recent experiments as examples, we discuss the conditions for sub-wavelength probing of optical field structures by
single trapped atoms. We calculate the achievable resolution, highlighting its connection to the fringe visibility in an interference
experiment. We show that seemingly different physical pictures, such as spatial averaging, phase modulation, and which-way
information, describe the situation equally and lead to identical results. The connection to Bohr's moving slit experiment
is pointed out.
Received 10 September 2002 Published online 17 December 2002 相似文献
19.
C. Champenois M. Büchner J. Vigué 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(3):363-374
Several three-grating Mach-Zehnder atomic interferometers have been built and operated in recent years but no general theory
of the contrast of the fringes produced by these apparatus is available. The purpose of this paper is to develop this theory,
based on the Fresnel-Kirchoff approximate treatment of diffraction. Such a theory has been developed by Turchette et al. [JOSA B 9, 1601 (1992)] but because the necessary multiple integrals were evaluated in a purely numerical way, this treatment was not
fully general. We show here how to reduce the computation by analytic means and we are thus able to calculate the contrast
with a modest numerical effort. Moreover, we get a simple insight of the contrast reduction related to several defects of
a real apparatus. We apply our calculations to existing interferometers as well as to an apparatus working with lithium which
is under construction in our laboratory.
Received: 24 April 1998 / Revised: 25 October 1998 / Accepted: 11 December 1998 相似文献
20.
J.G.C. Tempelaars R.J.W. Stas P.G.M. Sebel H.C.W. Beijerinck E.J.D. Vredenbregt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):113-121
We employ laser cooling to intensify and cool an atomic beam of metastable Ne(3
s) atoms. Using several collimators, a slower and a compressor we achieve a 20Ne* flux of 6×10
10
atoms/s in an 0.7 mm diameter beam traveling at 100 m/s, and having longitudinal and transverse temperatures of 25 mK and 300μK, respectively. This constitutes the highest flux in a concentrated beam achieved to date with metastable rare gas atoms.
We characterize the action of the various cooling stages in terms of their influence on the flux, diameter and divergence
of the atomic beam. The brightness and brilliance achieved are 2.1 ×10
21
s-1m-2sr-1 and 5.0 ×10
22
s-1m-2sr-1, respectively, comparable to the highest values reported for alkali-metal beams. Bright beams of the 21Ne and 22Ne isotopes have also been created.
Received 22 June 2001 相似文献