共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
R. Chicireanu Q. Beaufils A. Pouderous B. Laburthe-Tolra É. Maréchal L. Vernac J.-C. Keller O. Gorceix 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):189-195
We report the fast accumulation of a large number of
metastable 52Cr atoms in a mixed trap, formed by the
superposition of a strongly confining optical trap and a quadrupolar
magnetic trap. The steady state is reached after about 400 ms,
providing a cloud of more than one million metastable atoms at a
temperature of about 100 μK, with a peak density of 1018
atoms m-3. We have optimized the loading procedure, and
measured the light shift of the 5D4 state by analyzing how the
trapped atoms respond to a parametric excitation. We compare this
result to a theoretical evaluation based on the available
spectroscopic data for chromium atoms. 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.
85 Rb, 5s2S1/2(F”=2)→6p2P1/2(F’=2,3) absorption resonance with the 88Sr+, 5s2S1/2→5p2P1/2 transition is exploited to provide a simple, effective frequency reference for a laser cooling/fluorescence excitation source
applied to single Sr+ ions. A modulation-free frequency stabilization system has been designed which uses the differential signal from two frequency-displaced
beams traversing a Rb cell and which probe the Doppler-broadened Rb S–P lineshape at microwatt power levels. The method is
applied to frequency lock a 422-nm frequency-doubled diode laser system that is used for excitation of a single 88Sr+ ion. Stable, long-term laser cooling and fluorescence are achieved using the frequency-stabilized 422-nm source resulting
in observed ion confinement times without adjustment of over 8 h, together with an improvement in single-ion loading efficiency.
Received: 12 February 1998 相似文献
5.
L.G. Marcassa R.A.S. Zanon S. Dutta J. Weiner O. Dulieu V.S. Bagnato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):317-321
Using a technique that consists in ionizing atoms out of the 5P
1/2
fragments originated in the cold collision process, we have measured the contribution of the fine structure changing collision
(FS) to the total trap loss rate of cold 85Rb. Our results show that FS contribution is responsible for about 4% of the total trap loss. This result should stimulate
new theoretical discussions involving exoergic cold collisions.
Received 26 October 1998 and Received in final form 2 February 1999 相似文献
6.
V. Wippel C. Binder W. Huber L. Windholz M. Allegrini F. Fuso E. Arimondo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):285-291
A two element magneto-optical trap (MOT) for Na and 7Li or 6Li is used to cool and trap each of them separately. A fraction of the cold atoms is maintained in the first 2P3/2 excited state by the cooling laser. These excited state atoms are ionized by laser light in the near-UV region, giving rise
to a smaller number of trapped atoms and to different loading parameters. Photoionization cross-sections were derived out
of these data. They are in reasonable agreement with data previously obtained using thermal samples and with theoretical predictions.
Received 21 March 2001 and Received in final form 3 August 2001 相似文献
7.
J. Piilo E. Lundh K.-A. Suominen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):211-222
We have developed Monte Carlo wave function simulation schemes to study
cold collisions between magnesium atoms in a strong red-detuned laser field.
In order to address the strong-field problem, we extend the Monte Carlo wave function framework to include the partial wave
structure of the three-dimensional system. The average heating rate due to radiative collisions is calculated with two different
simulation schemes which are described in detail.
We show that the results of the two methods
agree and give estimates for the radiative collision heating rate for 24Mg atoms in a magneto-optical trap based on the 1S0–1P1 atomic laser cooling transition. 相似文献
8.
We have investigated how the formation of ultracold molecules in a rubidium magneto-optical trap is affected by the application of positively-chirped femtosecond laser pulses. The application of femtosecond pulses resulted in a reduction, rather than an increase, in the rate of detection of 85Rb2 and 87Rb2 triplet ground-state molecules, and compared this to the effects of non-chirped pulses, continuous-wave light, and the formation rate when no additional light was applied. A dependence on the amount of chirp of the femtosecond laser pulses suggests that the reduction in the molecular signal is the result of a coherent effect, and provides a promising indication that coherent control could be used to engineer the production of ultracold molecules. 相似文献
9.
F. Pereira Dos Santos F. Perales J. Léonard A. Sinatra Junmin Wang F. Saverio Pavone E. Rasel C.S. Unnikrishnan M. Leduc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):15-22
We present experimental results on the two-body loss rates in a magneto-optical trap of metastable helium atoms. Absolute
rates are measured in a systematic way for several laser detunings ranging from -5 to -30 MHz and at different intensities,
by monitoring the decay of the trap fluorescence. The dependence of the two-body loss rate coefficient β on the excited state
( 23
P
2) and metastable state ( 23
S
1) populations is also investigated. From these results we infer a rather uniform rate constant K
sp = (1±0.4)×10-7 cm3/s.
Received 8 September 2000 and Received in final form 19 December 2000 相似文献
10.
为了得到在高背景噪音下对弱信号光的提取,实验研究了基于87Rb D1线5S1/2F=2→5P1/2 F'=1跃迁的795 nm法拉第反常色散光学滤波器.充铷的样品池所含87Rb的比例高于自然铷,样品池处在均匀的磁场中并且夹在两个相互正交的偏振片之间.入射的探测光通过样品池,与原子相互作用,由于法拉第旋转效应实现滤波功能.改变实验条件,透射结果随之明显变化.当温度从340 K升高到360 K,透射谱的变化情况被细致记录,并且分析了导致透射情况变化的原因.在适当的工作温度以及磁场条件下,得到线宽为约220 MHz的超窄带透射谱线,谱线透过率约为48%.87Rb D1线的实验结果优于85Rb的吸收线. 相似文献
11.
E. Kirilov S. Putterman 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):683-691
We describe an efficient way to photoionize strontium atoms in a linear radio-frequency trap. We use a 2-photon second order
process to excite the autoionization resonance (4d2+5p2) 1D2 in neutral strontium (Sr). A doubled Ti:sapphire laser system is used at 431 nm to provide 100 fs pulses at 82 MHz. The fabrication
of the laser systems for addressing the Sr+ transitions necessary for laser cooling and excitation of quantum jumps, vacuum system and ion trap structure are also described.
With the current setup a easy and repeatable trapping of linear ion chains is readily achieved at very low Sr vapor pressures. 相似文献
12.
We investigate the properties of two separate dipole traps, realised using a cw mode-locked Ti:sapphire laser and a cw mode-locked
Nd:YVO4 laser, red-detuned by 25 nm and 284 nm, respectively. Approximately 103 laser-cooled 85Rb atoms were confined in the traps at ≈50 μK, with no observable heating after initial loading. The lifetimes of the traps
were consistent with limitations imposed by wavelength-dependent photoassociation losses and collisions with background vapour.
Determination of the ac Stark shift of the 780 nm cooling transition using a weak probe beam showed no observable difference
between using narrow-bandwidth or mode-locked trapping light. Techniques for trapping and focusing of atoms based on the dipole
force of blue and uv light become much more accessible through efficient doubling, tripling and quadrupling of mode-locked
sources. This opens up the possibility of manipulating more technologically interesting species.
Received: 30 September 1999 / Revised version: 21 December 1999 / Published online: 24 March 2000 相似文献
13.
A diode-laser optical frequency standard based on laser-cooled Ca atoms: Sub-kilohertz spectroscopy by optical shelving detection 总被引:2,自引:0,他引:2
C.W. Oates F. Bondu R.W. Fox L. Hollberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):449-460
We report an optical frequency standard at 657 nm based on laser-cooled/trapped Ca atoms. The system consists of a novel,
compact magneto-optic trap which uses 50 mW of frequency-doubled diode laser light at 423 nm and can trap >107 Ca atoms in 20 ms. High resolution spectroscopy on this atomic sample using the narrow 657 nm intercombination line resolves
linewidths (FWHM) as narrow as 400 Hz, the natural linewidth of the transition. The spectroscopic signal-to-noise ratio is
enhanced by an order of magnitude with the implementation of a “shelving" detection scheme on the 423 nm transition. Our present
apparatus achieves a fractional frequency instability of in 1 s with a potential atom shot-noise-limited performance of and excellent prospects for high accuracy.
Received 2 November 1998 相似文献
14.
I. D. Petrov T. Peters T. Halfmann S. Aloïse P. O'Keeffe M. Meyer V. L. Sukhorukov H. Hotop 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):181-193
The even parity mp1/2
5np′ and mp1/2
5nf′ autoionizing resonances of Ar, Kr, and Xe (m=3,4,5) were investigated experimentally and theoretically by one-photon
excitation from lower-lying intermediate levels. In particular, high
resolution measurements for the Ar(nf′), Kr(12p′,8f′), and Xe(8p′)
resonances are reported; lineshape parameters for these resonances have been
derived by a Fano-type analysis, thus yielding reduced resonance widths. The
experimental spectra and the resonance parameters are compared with
theoretical calculations which are based on the configuration interaction
Pauli–Fock approach including core polarization. The measured and
calculated lineshapes are in good agreement. In addition, theoretical predictions are presented
for other resonances, which have not yet been observed experimentally, and some
systematic trends are elucidated. 相似文献
15.
M. Lontano D. Ryutov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):347-351
We demonstrate the in situ detection of cold 87Rb atoms near a dielectric surface using the absorption of a weak, resonant evanescent wave. We have used this technique in
time of flight experiments determining the density of atoms falling on the surface. A quantitative understanding of the measured
curve was obtained using a detailed calculation of the evanescent intensity distribution. We have also used it to detect atoms
trapped near the surface in a standing-wave optical dipole potential. This trap was loaded by inelastic bouncing on a strong,
repulsive evanescent potential. We estimate that we trap 1.5×104 atoms at a density 100 times higher than the falling atoms.
Received 14 May 2002 Published online 8 October 2002
RID="a"
ID="a"e-mail: spreeuw@science.uva.nl 相似文献
16.
J. Dingjan B. Darquié J. Beugnon M.P.A. Jones S. Bergamini G. Messin A. Browaeys P. Grangier 《Applied physics. B, Lasers and optics》2006,82(1):47-51
We have constructed a pulsed laser system for the manipulation of cold 87Rb atoms. The system combines optical telecommunications components and frequency doubling to generate light at 780 nm. Using
a fast, fibre-coupled intensity modulator, we sliced output from a continuous laser diode into pulses with a length between
1.3 and 6.1 ns and a repetition frequency of 5 MHz. These pulses are amplified using an erbium-doped fibre amplifier, and
frequency-doubled in a periodically poled lithium niobate crystal, yielding a peak power up to 12 W. Using the resulting light
at 780 nm, we demonstrate Rabi oscillations on the F=2,mF=+2↔F′=3, m′
F=+3-transition of a single 87Rb atom.
PACS 32.80.Qk; 39.25.+k; 42.55.-f 相似文献
17.
S. Laha Y. C. Chen P. Gupta C. E. Simien Y. N. Martinez P. G. Mickelson S. B. Nagel T. C. Killian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):51-56
A study of ion equilibration in annular regions of ultracold strontium plasmas is reported. Plasmas are formed by photoionizing
laser-cooled atoms with a pulsed dye laser. The experimental probe is spatially-resolved absorption spectroscopy using the
2S1/2-2P1/2 transition of the Sr+ ion. The kinetic energy of the ions is calculated from the Doppler broadening of the spectrum, and it displays clear oscillations
during the first microsecond after plasma formation. The oscillations, which are a characteristic of strong coulomb coupling,
are fit with a simple phenomenological model incorporating damping and density variation in the plasma. 相似文献
18.
Y. Torii N. Shiokawa T. Hirano T. Kuga Y. Shimizu H. Sasada 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(3):239-242
We utilized a blue-detuned Laguerre-Gaussian (doughnut) laser beam to trap cold rubidium atoms by optical dipole force. ”Pulsed”
polarization gradient cooling was applied to the trapped atoms to suppress the trap loss due to heating caused by random photon
scattering of the trapping light. In this trap about 108 atoms were initially captured and the trap lifetime was 1.5 s, which was consistent with losses due to background gas collisions.
This trap can readily be applied to atom guiding, compression, and evaporative cooling.
Received: 10 July 1997 / Received in final form: 5 January 1998 / Accepted: 16 January 1998 相似文献
19.
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
20.
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