共查询到20条相似文献,搜索用时 15 毫秒
1.
Manipulation of cold atoms by an adaptable magnetic reflector 总被引:1,自引:0,他引:1
P. Rosenbusch B.V. Hall I.G. Hughes C.V. Saba E.A. Hinds 《Applied physics. B, Lasers and optics》2000,70(5):709-720
Adaptive optics for cold atoms has been experimentally realized by applying a bias magnetic field to a static magnetic mirror.
The mirror consist of a 12-mm-diameter piece of commercial videotape, having a sine wave of wavelength 25.4 μm recorded in
a single track across its width, curved to form a concave reflector with radius of curvature R=54 mm. We have studied the
performance of the mirror by monitoring the evolution of a 24 μK cloud of 85Rb atoms bouncing on it. A uniform static external magnetic field was added to the mirror field causing a corrugated potential
from which the atoms bounce with increased angular spread. The characteristic angular distribution of the surface normal is
mapped at the peak of the bounce for atoms dropped from a height of R/2 and at the peak of the second bounce for a drop height
of R/4. In a second experiment a time-dependent magnetic field was applied and the angular distribution of the cloud was measured
as a function of field frequency. In this scheme we demonstrate a corrugated potential whose time-dependent magnitude behaves
like a diffraction grating of variable depth. Finally a rotating field was added to generate a corrugated potential that moves
with a velocity given by the product of the external field rotation frequency and the videotape wavelength. This travelling
grating provides a new method of manipulation as cold atoms are transported across the surface by surfing along the moving
wave. Two theoretical methods have been developed to predict the behaviour of atoms reflecting from these stationary, variable
magnitude and moving corrugated potentials. A simple analytic theory provides excellent agreement for reflection from a stationary
corrugated potential and gives good agreement when extended to the case of a travelling grating. A Monte Carlo simulation
was also performed by brute force numeric integration of the equations of motion for atoms reflecting from all three corrugated
potential cases.
Received: 1 December 1999 / Revised version: 3 February 2000 / Published online: 5 April 2000 相似文献
2.
We have theoretically and experimentally investigated the focusing properties of a detuned pulsed standing wave onto a beam
of neutral atoms. In close analogy to the continuous-wave situation the dipole force leads to a periodic focusing of atoms
with a period of λ/2, provided an adiabatic condition is fulfilled. Pulsed laser light is conveniently converted to short
wavelengths and hence offers advantages in the application of atom lithography with elements of technological interest having
blue or UV resonance lines.
Received: 6 October 1999 / Revised version: 3 February 2000 / Published online: 5 April 2000 相似文献
3.
D. Schrader S. Kuhr W. Alt M. Müller V. Gomer D. Meschede 《Applied physics. B, Lasers and optics》2001,73(8):819-824
Using optical dipole forces we have realized controlled transport of a single or any desired small number of neutral atoms
over a distance of a centimeter with sub-micrometer precision. A standing wave dipole trap is loaded with a prescribed number
of cesium atoms from a magneto-optical trap. Mutual detuning of the counter-propagating laser beams moves the interference
pattern, allowing us to accelerate and stop the atoms at preselected points along the standing wave. The transportation efficiency
is close to 100%. This optical ‘single-atom conveyor belt’ represents a versatile tool for future experiments requiring deterministic
delivery of a prescribed number of atoms on demand.
Received: 6 July 2001 / Published online: 23 November 2001 相似文献
4.
E. Peik M. Ben Dahan I. Bouchoule Y. Castin C. Salomon 《Applied physics. B, Lasers and optics》1997,65(6):685-692
Received: 30 May 1997 相似文献
5.
Atom lithography with a cold, metastable neon beam 总被引:1,自引:0,他引:1
P. Engels S. Salewski H. Levsen K. Sengstock W. Ertmer 《Applied physics. B, Lasers and optics》1999,69(5-6):407-412
We study different aspects of atom lithography with metastable neon atoms. Proximity printing of stencil masks is used to
test suitable resists that are sensitive to the internal energy of the atoms, including dodecanethiols on gold and octadecyltrichlorosilanes
grown on a SiO2 surface. As an example of patterning the atomic beam with laser light, we create parallel line structures on the surface
with a periodicity of half the laser wavelength by locally de-exciting the atoms in a standing quenching wave.
Received: 29 June 1999 / Revised version: 30 August 1999 / Published online: 10 November 1999 相似文献
6.
Adiabatic focusing of cold atoms in a blue-detuned laser standing wave is analyzed. It is shown that using repulsive light
forces that push atoms towards dark regions and thus minimizes heating, cold atoms can be adiabatically compressed by more
than an order of magnitude to yield background-free sub-10-nm (rms) spots. The optimal parameters for the atomic lens and
the maximal compression ratio are predicted using an analytic model and found to be in agreement with the exact results of
our Monte Carlo simulations. A combined adiabatic-coherent scheme is proposed and shown to yield 8.8 nm spot size even for
a thermal atomic beam.
Received: 1 October 1999 / Revised version: 13 December 1999 / Published online: 5 April 2000 相似文献
7.
K.W. Madison C.F. Bharucha P.R. Morrow S.R. Wilkinson Q. Niu B. Sundaram M.G. Raizen 《Applied physics. B, Lasers and optics》1997,65(6):693-700
Received: 8 July 1997 相似文献
8.
B. Bahar J. Castellanos U. Hübner C.O. Weiss 《Applied physics. B, Lasers and optics》1998,66(3):359-366
Received: 12 March 1997/Revised version: 30 July 1997 相似文献
9.
Cold atomic beam from a rubidium funnel 总被引:1,自引:0,他引:1
We report an experimental demonstration of a continuous, slow and cold beam of rubidium atoms from a two-dimensional magneto-optic
trap or atomic funnel. Typically 7.3(7)×108 atoms/s are ejected from the funnel with a variable velocity in the range 2–8 m/s and a temperature of 45–55 μK in the moving
frame. This represents the first demonstration of sub-Doppler laser cooling in an atomic beam and temperatures as low as ≈25 μK
have been observed.
Received: 30 September 1999 / Published online: 5 April 2000 相似文献
10.
A. Goepfert F. Lison R. Schütze R. Wynands D. Haubrich D. Meschede 《Applied physics. B, Lasers and optics》1999,69(3):217-222
We have studied guidance and deflection of a beam of cesium atoms by a strong toroidal magnetic quadrupole field. The beam
guide is made from permanent magnets sustaining a radial field gradient of 2.8 T/cm. Atoms with moderate longitudinal velocities
ranging from 30 m/s to 70 m/s were inserted across the 10-mm-diameter aperture of a 24.5° arc with radius 300 mm. We have
measured transmission and beam divergence and find good agreement with ray-tracing calculations and analytical estimates.
The magnetic beam guide allows for 100% transmission of heavy atoms over large angles.
Received: 9 November 1998 / Revised version: 6 April 1999 / Published online: 30 July 1999 相似文献
11.
Reflection of cold atoms from an array of current-carrying wires 总被引:1,自引:0,他引:1
D.C. Lau A.I. Sidorov G.I. Opat R.J. McLean W.J. Rowlands P. Hannaford 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):193-199
We report the realization of a new type of magnetostatic mirror for slowly moving atoms which comprises a planar array of
parallel wires alternately carrying electric current in opposite directions. One of the features of this atomic mirror is
that the magnetic field may be readily varied, switched or modulated by altering the current in the wires. Reflection signals
close to 100% at a pulsed current of 3 A are demonstrated for a beam of free-falling laser-cooled cesium atoms at normal incidence.
The current dependence of the reflection signals exhibits structure which is associated with the sequential onset of reflection
of cesium 62
S
1/2
, F=4 atoms in the m=+4, +3, +2 and +1 magnetic states. Measurements of the spatial distribution of the reflected atoms indicate the reflection
is predominantly specular at currents of 3 A.
Received: 31 August 1998 / Accepted: 6 October 1998 相似文献
12.
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
13.
As a new method for measuring the spatial distribution of Bose–Einstein condensates, the magnetic resonance imaging (MRI)
method is proposed and studied in detail. The basic concepts, the resolution limit and the formalism of the MRI method are
presented. It is expected that a resolution higher than that in optical imaging methods can be obtained by using the MRI method.
Results of simulation of expected MRI signals for Bose–Einstein condensates containing dark solitons are also presented.
Received: 27 September 2001 / Revised version: 24 October 2001 / Published online: 17 January 2002 相似文献
14.
A collision of two-component Bose-Einstein condensates in the presence of Raman coupling is proposed and studied by numerical
simulations. Raman transitions are found to be able to reduce collision-produced irregular excitations by forming a time-averaged
attractive optical potential. Raman transitions also support a kind of dark soliton pair in two-component Bose-Einstein condensates.
Soliton pairs and their remnant single solitons are shown to be controllable by adjusting the initial relative phase between
the two colliding condensates or the two-photon detuning of Raman transitions.
Received: 5 February 2001 / Published online: 27 April 2001 相似文献
15.
J. Stenger S. Inouye D.M. Stamper-Kurn A.P. Chikkatur D.E. Pritchard W. Ketterle 《Applied physics. B, Lasers and optics》1999,69(5-6):347-352
Two sets of studies concerning the interaction of off-resonant light with a sodium Bose–Einstein condensate are described.
In the first set, properties of a Bose–Einstein condensate were studied using Bragg spectroscopy. The high momentum and energy
resolution of this method allowed a spectroscopic measurement of the mean-field energy and of the intrinsic momentum distribution
of the condensate. Depending on the momentum transfer, both the phonon regime as well as the free-particle regime could be
explored. In the second set of studies, the cigar-shaped condensate was exposed to a single off-resonant laser beam and highly
directional scattering of light and atoms was observed. This collective light scattering was caused by the long coherence
time of the quasi-particles in the condensate and resulted in a new form of matter wave amplification.
Received: 26 June 1999 / Revised version: 21 September 1999 / Published online: 10 November 1999 相似文献
16.
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
17.
Bright atomic beam by a temporal Zeeman acceleration 总被引:1,自引:0,他引:1
Y. Fukuyama H. Kanou V.I. Balykin K. Shimizu 《Applied physics. B, Lasers and optics》2000,70(4):561-565
A novel method to produce a slow, monochromatic, and bright pulsed atomic beam from a magneto-optical trap by switching the
magnetic field of the trap is proposed. A pulsed lithium atomic beam with a brightness of 1.1×1015 /sr s and a velocity of 13 m/s was produced as an experimental proof of this technique. The conversion efficiency from the
trap into the atomic pulse was nearly 100%.
Received: 22 October 1999 / Revised version: 15 November 1999 / Published online: 8 March 2000 相似文献
18.
We propose a novel scheme to form a 2D dark optical surface lattice (DOSL) for cold atoms on the surface of the dense flint glass by using two sets of blue-detuned evanescent wave interference fields and a blue-detuned evanescent wave field. In the 2D DOSL, cold atoms will be trapped in the vicinity of minimum intensity and suffered the minimal light shift as well as the lowest coherence loss. The total potential and trap-depth of the individual optical micro-trap in the 2D DOSL are high enough to trap cold atoms (T = 120 μK) released from the standard magneto-optical trap (MOT), and atoms trapped in the 2D DOSL can be cooled to several μK with the efficient intensity-gradient Sisyphus cooling. The lattice constant of the DOSL can be controllable by changing the incident angles of lights. 相似文献
19.
W. DeGraffenreid J. Ramirez-Serrano Y.-M. Liu R. Napolitano A. Rosenbaum J. Weiner 《Applied physics. B, Lasers and optics》2000,71(6):881-884
We report measurements of the angular distribution of optical suppression in photoassociative ionization collisions taking
place within a bright, slow Na atom beam. At a collision “temperature” (T=Ekin/kB) of about 5 mK we observe rich structure in the suppression measure as a function of the angle between the atom-beam axis
and the polarization axis of the suppressor light beam. This structure cannot be explained by the superposition of individual
partial-wave contributions to the suppression measure, and we propose a partial-wave interference phenomenon to account for
it.
Received: 9 June 2000 / Revised version: 21 September 2000 / Published online: 8 November 2000 相似文献
20.
S. Urabe M. Watanabe H. Imajo K. Hayasaka U. Tanaka R. Ohmukai 《Applied physics. B, Lasers and optics》1998,67(2):223-227
1/2 -D5/2 electric-quadrupole-allowed transitions of a laser-cooled Ca+ ion in a small rf trap. The electron shelving method was used to measure the absorption spectrum of the electric-quadrupole-allowed
transitions, and the motional sidebands due to the secular motion of the ion in the harmonic potential well of the rf trap
were completely resolved. The effective temperature of the ion, estimated by comparing the observed sideband intensities with
the theoretical ones, was less than 4.4 mK. This result is in good agreement with that obtained from the analysis of the linewidth
measurement.
Received: 18 March 1998 相似文献