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1.
The ion trap quantum information processor 总被引:8,自引:0,他引:8
A. Steane 《Applied physics. B, Lasers and optics》1997,64(6):623-643
Received: 16 October 1996/Revised version: 2 April 1997 相似文献
2.
A. di Stefano D. Wilkowski J.H. Müller E. Arimondo 《Applied physics. B, Lasers and optics》1999,69(4):263-268
We have operated a magneto-optical trap and optical molasses for the laser cooling of cesium atoms on the basis of a five-beam
laser configuration. For the magneto-optical trap two laser beams counterpropagate along the axis of a quadrupole trap and
the remaining three beams propagate in the orthogonal plane at 120° to each other. The same optical configuration was used
for the optical molasses. We have tested the efficiency in atom collection and the temperatures reached in both cooling processes.
In comparison to previous results on a six-beam configuration, a lower number of atoms is collected, while comparable densities
are realized. The atomic temperatures have been measured through a delayed shadow-image technique, where one of the running-wave
cooling beams produces an absorptive image of the atoms on a camera.
Received: 14 January 1999 / revised version: 23 June 1999 / Published online: 8 September 1999 相似文献
3.
Received: 5 February 1998/Revised version: 18 March 1998 相似文献
4.
Micro-bubbles have been stably trapped in liquid ethanol by a focused argon laser beam. Two equilibrium points where bubbles
can be trapped are observed to be at the center and the rim of the laser beam. The light force is also able to push a bubble
into the liquid to a position well below the liquid surface. Both the light-pressure force and the fluid force induced by
the convection of the liquid medium are calculated. The results clearly show that these two kinds of forces account for the
formation of trapping potential.
Received: 3 February 2000 / Revised version: 6 July 2000 / Published online: 8 November 2000 相似文献
5.
We theoretically investigated the mass dependence of the sympathetic cooling rate of gas-phase ions trapped in a linear radio-frequency-quadrupole
ion trap. Using an a priori molecular dynamical calculation, tracing numerically with Newtonian equations of motion, we found
that ions with a mass greater than 0.54±0.04 times that of the laser-cooled ions are sympathetically cooled; otherwise, they
are heated. To understand the mass dependence obtained using the molecular-dynamical calculation, we made a heat-exchange
model of sympathetic cooling, which shows that the factor of 0.54±0.04 is a consequence of absence of micro-motion along the
axis of the linear ion trap.
Received: 10 December 2001 / Revised version: 28 January 2002 / Published online: 14 March 2002 相似文献
6.
High-resolution atomic channeling using velocity-controlled atoms may be able to overcome precision limitations of the conventional
atom lithography. We have experimentally clarified the dependence of line width and contrast of atomic patterns in the channeling
region on the velocity spread of the atomic source for the first time. Thermal or velocity-selected atomic beams prepared
with a one-dimensional magneto-optical trap were employed as the atomic sources. We investigated the channeling characteristics
by measuring the frequency shifts of the atomic absorption spectra in an intense standing wave light field. As a result, we
can show that narrower line width and higher contrast atomic patterns are obtained as the velocity spread becomes narrower.
An atomic pattern with an estimated line width of 57 nm was generated when the velocity spread of the atomic source was almost
50 m/s, that is, 1/6 that of the thermal beam.
Received: 16 June 2001 / Published online: 7 November 2001 相似文献
7.
M. Keller B. Lange K. Hayasaka W. Lange H. Walther 《Applied physics. B, Lasers and optics》2003,76(2):125-128
By combining the technologies of ion trapping and cavity QED, we have achieved deterministic coupling of single ions to an
optical field. By Doppler cooling, the spread of the ion’s wavepacket was reduced to 42 nm, corresponding to Lamb–Dicke localization.
As an application, we have measured the three-dimensional structure of cavity eigenmodes with sub-wavelength precision. The
setup presented is suited for the controlled coherent processing of atomic and photonic quantum information. Examples include
the triggered generation of single photons and two-ion quantum gates.
Received: 20 August 2002 / Revised version: 16 December 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +49-89/32905-200, E-mail: keller@mpq.mpg.de 相似文献
8.
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
9.
G. Schrade P.J. Bardroff R.J. Glauber C. Leichtle V. Yakovlev W.P. Schleich 《Applied physics. B, Lasers and optics》1997,64(2):181-191
We show that three real-valued parameters govern the quantum motion of an ion stored in the Paul trap. These parameters are
two angles of rotation in phase space and a squeezing parameter. The time dependence of these parameters simplifies considerably
using Floquet solutions. This allows us to use the method of quantum state endoscopy to measure a pure state of the vibratory
motion of an ion taking into account the full time dependence of the trapping potential.
Received: 19 June 1996 相似文献
10.
Atomic beam guide by a one-dimensional magneto-optical trap 总被引:1,自引:0,他引:1
An atomic beam has been collimated, compressed, and deflected simultaneously by an atomic beam guide based on an inclined
one-dimensional magneto-optical trap (1D-MOT). Isotope-selected rubidium atoms were extracted from the naturally-mixed thermal
atomic beam with this method. We could manipulate the transverse displacement of the deflected beam precisely by adjusting
the current in the copper rods to generate the quadrupole magnetic field. We could extract more than 50% of the incident atoms
as a deflection beam when we combined this deflection technique with the atomic deceleration using a broadband spectral light.
Received: 10 December 1998 / Published online: 24 June 1999 相似文献
11.
K. Dholakia G. Zs. K. Horvath W. Power D. M. Segal R. C. Thompson 《Applied physics. B, Lasers and optics》1995,60(4):375-382
We demonstrate a pulse-probe method for measuring the ion-cloud rotation frequency in a Penning trap. We show that it is useful over a range of parameters not accessible to the photon correlation method of Dholakia et al. [1]. In particular, the pulse-probe method works for larger clouds than the photon-correlation method. We show that the pulse-probe method measures the space-charge-shifted frequency and gives us the optical pumping times within clouds. Furthermore, we show that, for Mg+ ions, it is capable of measuring much higher degrees of space-charge shift than the photon-correlation method. Improvements to the method may enable its use in measuring diffusion rates for ions in clouds. 相似文献
12.
We analyse the effects of atom–atom collisions on a collective laser cooling scheme. We derive a quantum master equation which
describes the laser cooling in presence of atom–atom collisions in the weak-condensation regime. Using such equation, we perform
Monte Carlo simulations of the population dynamics in one and three dimensions. We observe that the ground-state laser-induced
condensation is maintained in the presence of collisions. Laser cooling causes a transition from a Bose–Einstein distribution
describing collisionally induced equilibrium, to a distribution with an effective zero temperature. We analyse also the effects
of atom–atom collisions on the cooling into an excited state of the trap.
Received: 18 June 1999 / Revised version: 24 September 1999 / Published online: 10 November 1999 相似文献
13.
H.C. Nägerl W. Bechter J. Eschner F. Schmidt-Kaler R. Blatt 《Applied physics. B, Lasers and optics》1998,66(5):603-608
Received: 6 August 1997/Revised version: 21 October 1997 相似文献
14.
We develop a mean-field approach to include dipole-dipole interactions and quantum statistics in the atomic dynamics in bright
and dark optical lattices including the proper spatial potentials instead of a simple δ-approximation. For classical distinguishable
particles the results are even quantitatively similar to the properly scaled δ-function model. As the dominant effect bright
and dark lattices exhibit opposite shifts in the lattice band energies and differ in their localisation properties as a function
of density. The spatial-dependent potential allows strong modifications also in dark lattices, but the main conclusions obtained
in the δ-approximation turn out to be still valid. Interestingly, important quantitative differences from the δ-model can
occur as far as the effect of statistics in concerned, especially for fermions. We study the quantum statistical effects as
a function of detuning and lattice well depths and identify the case of lattices with deep wells and large detunings as the
preferred parameter region to observe them.
Received 24 November 1999 / revised version: 24 June 1999 / Published online: 8 September 1999 相似文献
15.
Writing a superlattice with light forces 总被引:1,自引:0,他引:1
Th. Schulze B. Brezger R. Mertens M. Pivk T. Pfau J. Mlynek 《Applied physics. B, Lasers and optics》2000,70(5):671-674
In atom lithography the conventional roles played by light and matter are reversed. Instead of using a solid mask to pattern
a light beam, a mask of light is used to pattern a beam of neutral atoms. In this paper we report the production of different
chromium dot arrays with quadratic symmetry. The lattice period depends on the relative polarization and the phase of the
two standing waves generating the light mask. A small angular misalignment of the laser beams breaks the high symmetry and
a chromium superlattice is written, that is a continuous periodic change between two different quadratic lattices. The structures
exhibit lines with a FWHM below 50 nm and clearly separated chromium dots with a FWHM below 70 nm.
Received: 30 September 1999 / Revised version: 14 February 2000 / Published online: 5 April 2000 相似文献
16.
We investigate the production of long-lived metastable (43
P
2
) calcium atoms in a magneto-optical trap (MOT) operating on the 41
S
0
?41
P
1
transition at 423 nm. For excited 41
P
1
atoms a weak decay channel into the triplet states 43
P
2
and 43
P
1
exists via the 31
D
2
state. The undesired 43
P
1
atoms decay back to the ground state within 0.4 ms and can be fully recaptured if the illuminated trap volume is sufficientlylarge.
We obtain a flux of above 1010 atoms/s into the 43
P
2
state. We find that our MOT lifetime of 23 ms is mainly limited by this loss channel, and thus the 43
P
2
production is not hampered by inelastic collisions. If we close the loss channel by repumping the 31
D
2
atoms with a 671 nm laser back into the MOT cycling transition, a non-exponential 72 ms trap decay is observed, indicating
the presence of inelastic two-body collisions between 41
S
0
and 41
P
1
atoms.
Received: 10 July 2001 / Revised version: 22 October 2001 / Published online: 23 November 2001 相似文献
17.
A.B. Mundt A. Kreuter C. Russo C. Becher D. Leibfried J. Eschner F. Schmidt-Kaler R. Blatt 《Applied physics. B, Lasers and optics》2003,76(2):117-124
We demonstrate coherent coupling of the quadrupole S1/2D5/2 optical transition of a single trapped 40Ca+ ion to the standing wave field of a high-finesse cavity. The dependence of the coupling on temporal dynamics and spatial
variations of the intracavity field is investigated in detail. By precisely controlling the position of the ion in the cavity
standing wave field and by selectively exciting vibrational state-changing transitions the ion’s quantized vibration in the
trap is deterministically coupled to the cavity mode. We confirm coherent interaction of ion and cavity field by exciting
Rabi oscillations with short resonant laser pulses injected into the cavity, which is frequency-stabilized to the atomic transition.
Received: 23 August 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. E-mail: christoph.becher@uibk.ac.at
RID="**"
ID="**"Present address: Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO 80305, USA 相似文献
18.
V. Gomer B. Ueberholz S. Knappe F. Strauch D. Frese D. Meschede 《Applied physics. B, Lasers and optics》1998,67(6):689-697
Received: 4 September 1998 相似文献
19.
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
20.
We demonstrate two schemes for the coherent excitation of Rydberg atoms in an ultracold gas of rubidium atoms employing the three-level ladder system 5S1/2-5P3/2-n?j. In the first approach rapid adiabatic passage with pulsed laser fields yields Rydberg excitation probabilities of 90% in the center of the laser focus. In a second experiment two-photon Rydberg excitation with continuous-wave fields is applied which results in Rabi oscillations between the ground and Rydberg state. The experiments represent a prerequisite for the control of interactions in ultracold Rydberg gases and the application of ultracold Rydberg gases for quantum information processing. 相似文献