230 research outputs found
Double Bragg diffraction: A tool for atom optics
The use of retro-reflection in light-pulse atom interferometry under
microgravity conditions naturally leads to a double-diffraction scheme. The two
pairs of counterpropagating beams induce simultaneously transitions with
opposite momentum transfer that, when acting on atoms initially at rest, give
rise to symmetric interferometer configurations where the total momentum
transfer is automatically doubled and where a number of noise sources and
systematic effects cancel out. Here we extend earlier implementations for Raman
transitions to the case of Bragg diffraction. In contrast with the
single-diffraction case, the existence of additional off-resonant transitions
between resonantly connected states precludes the use of the adiabatic
elimination technique. Nevertheless, we have been able to obtain analytic
results even beyond the deep Bragg regime by employing the so-called "method of
averaging," which can be applied to more general situations of this kind. Our
results have been validated by comparison to numerical solutions of the basic
equations describing the double-diffraction process.Comment: 26 pages, 20 figures; minor changes to match the published versio
A compact dual atom interferometer gyroscope based on laser-cooled rubidium
We present a compact and transportable inertial sensor for precision sensing
of rotations and accelerations. The sensor consists of a dual Mach-Zehnder-type
atom interferometer operated with laser-cooled Rb. Raman processes are
employed to coherently manipulate the matter waves. We describe and
characterize the experimental apparatus. A method for passing from a compact
geometry to an extended interferometer with three independent atom-light
interaction zones is proposed and investigated. The extended geometry will
enhance the sensitivity by more than two orders of magnitude which is necessary
to achieve sensitivities better than rad/s/.Comment: 9 pages, 8 figure
A robust, high-flux source of laser-cooled ytterbium atoms
We present a high-flux source of cold ytterbium atoms that is robust, lightweight and low-maintenance. Our apparatus delivers 1 Ă 109 atoms sâ1 into a 3D magneto-optical trap without requiring water cooling or high current power supplies. We achieve this by employing a Zeeman slower and a 2D magneto-optical trap fully based on permanent magnets in Halbach configurations. This strategy minimizes mechanical complexity, stray magnetic fields, and heat production while requiring little to no maintenance, making it applicable to both embedded systems that seek to minimize electrical power consumption, and large scale experiments to reduce the complexity of their subsystems
Extended coherence time on the clock transition of optically trapped Rubidium
Optically trapped ensembles are of crucial importance for frequency
measurements and quantum memories, but generally suffer from strong dephasing
due to inhomogeneous density and light shifts. We demonstrate a drastic
increase of the coherence time to 21 s on the magnetic field insensitive clock
transition of Rb-87 by applying the recently discovered spin self-rephasing.
This result confirms the general nature of this new mechanism and thus shows
its applicability in atom clocks and quantum memories. A systematic
investigation of all relevant frequency shifts and noise contributions yields a
stability of 2.4E-11 x tau^(-1/2), where tau is the integration time in
seconds. Based on a set of technical improvements, the presented frequency
standard is predicted to rival the stability of microwave fountain clocks in a
potentially much more compact setup.Comment: 5 pages, 4 figure
Penning collisions of laser-cooled metastable helium atoms
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 on the excited state
() and metastable state () populations is also investigated.
From these results we infer a rather uniform rate constant
cm/s.Comment: 8 pages, 9 figures, Revte
Versatile compact atomic source for high resolution dual atom interferometry
We present a compact Rb atomic source for high precision dual atom
interferometers. The source is based on a double-stage magneto-optical trap
(MOT) design, consisting of a 2-dimensional (2D)-MOT for efficient loading of a
3D-MOT. The accumulated atoms are precisely launched in a horizontal moving
molasses. Our setup generates a high atomic flux ( atoms/s) with
precise and flexibly tunable atomic trajectories as required for high
resolution Sagnac atom interferometry. We characterize the performance of the
source with respect to the relevant parameters of the launched atoms, i.e.
temperature, absolute velocity and pointing, by utilizing time-of-flight
techniques and velocity selective Raman transitions.Comment: uses revtex4, 9 pages, 12 figures, submitted to Phys. Rev.
Efficient magneto-optical trapping of a metastable helium gas
This article presents a new experiment aiming at BEC of metastable helium
atoms. It describes the design of a high flux discharge source of atoms and a
robust laser system using a DBR diode coupled with a high power Yb doped fiber
amplifier for manipulating the beam of metastable atoms. The atoms are trapped
in a small quartz cell in an extreme high vacuum. The trapping design uses an
additional laser (repumper) and allows the capture of a large number of
metastable helium atoms (approximately ) in a geometry favorable for
loading a tight magnetostatic trap.Comment: 12 pages, 7 figures, Late
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