共查询到20条相似文献,搜索用时 78 毫秒
1.
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
2.
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
3.
G. Morigi H. Walther 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):261-269
We study from the point of view of quantum information the properties of the collective oscillations of a linear chain of
ions trapped in a linear Paul trap and composed of two ion species. We discuss extensively sympathetic cooling of the chain
and the effect of anharmonicity on laser-cooling and quantum-information processing.
Received 19 May 2000 相似文献
4.
R. deCarvalho J.M. Doyle B. Friedrich T. Guillet J. Kim D. Patterson J.D. Weinstein 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):289-309
Over the past three years we have developed the technique of buffer-gas cooling and loading of atoms and molecules into magnetic
traps. Buffer-gas cooling relies solely on elastic collisions (thermalization) of the species-to-be-trapped with a cryogenically
cooled helium gas and so is independent of any particular energy level pattern. This makes the cooling technique general and
potentially applicable to any species trappable at the temperature of the buffer gas (as low as 240 mK). Using buffer-gas
loading, paramagnetic atoms (europium and chromium) as well as a molecule (calcium monohydride) were trapped at temperatures
around 300 mK. The numbers of the trapped atoms and molecules were respectively about 1012 and 108. The atoms and molecules were produced by laser ablation of suitable solid precursors. In conjunction with evaporative cooling,
buffer-gas loaded magnetic traps offer the means to further lower the temperature and increase the density of the trapped
ensemble to study a large variety of both static (spectra) and dynamic (collisional cross-sections) properties of many atoms
and molecules at ultra-low temperatures. In this article we survey our main results obtained on Cr, Eu, and CaH and outline
prospects for future work.
Received 2 November 1998 and Received in final form 19 February 1999 相似文献
5.
C. Fort A. Bambini L. Cacciapuoti F.S. Cataliotti M. Prevedelli G.M. Tino M. Inguscio 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(2):113-118
We report on a theoretical and experimental investigation of 39K magneto-optical trapping. The small hyperfine splitting characterizing the upper level of the cooling transition affects
the cooling mechanism. In order to model the atom-laser interaction, the whole level structure of the D2 line has to be taken into account. Two different regimes have been recognized, one optimizing the loading of the trap, the
second minimizing the temperature of the atoms. We investigated these two regimes experimentally and found results in agreement
with the theoretical predictions.
Received: 6 March 1998 / Received in final form: 13 May 1998 / Accepted: 13 May 1998 相似文献
6.
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
7.
G. Bruun Y. Castin R. Dum K. Burnett 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):433-439
We develop an extension of the well-known BCS-theory to systems with trapped fermionic atoms. The theory fully includes the
quantized energy levels in the trap. The key ingredient is to model the attractive interaction between two atoms by a pseudo-potential
which leads to a well defined scattering problem and consequently to a BCS-theory free of divergences. We present numerical
results for the BCS critical temperature and the temperature dependence of the gap. They are used as a test of existing semi-classical
approximations.
Received 18 December 1998 相似文献
8.
Y. Castin R. Dum 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):399-412
We investigate minimal energy solutions with vortices for an interacting Bose-Einstein condensate in a rotating trap. The
atoms are strongly confined along the axis of rotation z, leading to an effective 2D situation in the x-y plane. We first use a simple numerical algorithm converging to local minima of energy. Inspired by the numerical results
we present a variational ansatz in the regime where the interaction energy per particle is stronger than the quantum of vibration
in the harmonic trap in the x-y plane, the so-called Thomas-Fermi regime. This ansatz allows an easy calculation of the energy of the vortices as function
of the rotation frequency of the trap; it gives a physical understanding of the stabilisation of vortices by rotation of the
trap and of the spatial arrangement of vortex cores. We also present analytical results concerning the possibility of detecting
vortices by a time-of-flight measurement or by interference effects. In the final section we give numerical results for a
3D configuration.
Received 16 December 1998 and Received in final form 18 March 1999 相似文献
9.
10.
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
11.
M. Kajita 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):55-59
Collisions between linear polar molecules that were electrostatically trapped were investigated. The collisional transition
from a low to a high field seeking state (inelastic collision) causes trap loss. The efficiency of evaporative cooling is
improved at higher elastic collision rates. We calculated cross-sections of inelastic and elastic collision using a semi-classical
treatment.
Received 6 December 2001 / Received in final form 26 February 2002 Published
online 28 June 2002 相似文献
12.
E. Peik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(2):179-183
An electrodynamic trap is proposed that stores cold neutral atoms or nonpolar molecules in their ground state as well as in
excited states by means of the quadratic Stark effect. The trap uses an oscillating hexapole field and a superposed static
homogeneous field. The dynamics of an atom in this trap can be described as a harmonic oscillation in a static pseudopotential.
Stability criteria and sample parameters for a number of atomic species are given.
Received: 7 August 1998 / Received in final form: 7 January 1999 相似文献
13.
F. Schmidt-Kaler J. Eschner G. Morigi C.F. Roos D. Leibfried A. Mundt R. Blatt 《Applied physics. B, Lasers and optics》2001,73(8):807-814
A novel method of ground-state laser cooling of trapped atoms utilizes the absorption profile of a three- (or multi-) level
system that is tailored by a quantum interference. With cooling rates comparable to conventional sideband cooling, lower final
temperatures may be achieved. The method was experimentally implemented to cool a single Ca+ ion to its vibrational ground state. Since a broad band of vibrational frequencies can be cooled simultaneously, the technique
will be particularly useful for the cooling of larger ion strings, thereby being of great practical importance for initializing
a quantum register based on trapped ions. We also discuss its application to different level schemes and for ground-state
cooling of neutral atoms trapped by a far-detuned standing wave laser field.
Received: 10 July 2001 / Published online: 23 November 2001 相似文献
14.
C. Champenois M. Knoop M. Herbane M. Houssin T. Kaing M. Vedel F. Vedel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):105-111
Frequency standard applications and ultra-high resolution spectroscopy of a confined single ion require traps of drastically
reduced dimensions (about or below 1 mm). These small dimensions increase the sensitivity of the trapping behavior to imperfections
in the trap geometry and to patch potentials. For the aim of the metrological laser interrogation of a single Ca+ ion, a miniature cylindrical ring trap was built. In order to optimize the laser cooling process and to reach strong binding
conditions, the boundaries of the stability diagram and the zones of low confinement as well as the ion motion properties
were characterized.
Received 14 November 2000 and Received in final form 1st February 2001 相似文献
15.
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
16.
J.H. Thywissen M. Olshanii G. Zabow M. Drndić K.S. Johnson R.M. Westervelt M. Prentiss 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):361-367
We describe how tightly confining magnetic waveguides for atoms can be created with microfabricated or nanofabricated wires.
Rubidium atoms guided in the devices we have fabricated would have a transverse mode energy spacing of K. We discuss the creation of a single-mode waveguide for atom interferometry whose depth is comparable to magneto-optical
trap (MOT) temperatures. We also discuss the application of microfabricated waveguides to low-dimensional systems of quantum
degenerate gases, and show that confinement can be strong enough to observe fermionization in a strongly interacting bosonic
ensemble.
Received 1st December 1998 and Received in final form 23 February 1999 相似文献
17.
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
18.
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
19.
D. Boiron C. Mennerat-Robilliard J.-M. Fournier L. Guidoni C. Salomon G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):373-377
We present the results of two experiments where cold cesium atoms are trapped in a speckle field. In the first experiment,
a YAG laser creates the speckle pattern and induces a far-detuned dipole potential which is a nearly-conservative potential.
Localization of atoms near the intensity maxima of the speckle field is observed. In a second experiment we use two counterpropagating
laser beams tuned close to a resonance line of cesium and in the linlin configuration, one of them being modulated by a holographic diffuser that creates the speckle field. Three-dimensional
cooling is observed. Variations of the temperature and of the spatial diffusion coefficient with the size of a speckle grain
are presented.
Received 16 December 1998 and Received in final form 16 April 1999 相似文献
20.
E. Rasel F. Pereira Dos Santos F. Saverio Pavone F. Perales C.S. Unnikrishnan M. Leduc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):311-316
We report a study of transverse laser cooling on a metastable helium beam using spectrally broadened diode lasers (“white
light") to increase its flux. For this purpose, beam profile and atomic flux versus laser power and other parameters have been characterized. We have performed experiments to compare this technique with other
transverse cooling methods using monochromatic light. Best results are obtained with a “ziz-zag" configuration using “white
light".
Received 21 December 1998 and Received in final form 27 May 1999 相似文献