36 research outputs found
A steady-state magneto-optical trap with 100 fold improved phase-space density
We demonstrate a continuously loaded magneto-optical trap
(MOT) with a steady-state phase-space density of . This
is two orders of magnitude higher than reported in previous steady-state MOTs.
Our approach is to flow atoms through a series of spatially separated laser
cooling stages before capturing them in a MOT operated on the 7.4-kHz linewidth
Sr intercombination line using a hybrid slower+MOT configuration. We also
demonstrate producing a Bose-Einstein condensate at the MOT location, despite
the presence of laser cooling light on resonance with the 30-MHz linewidth
transition used to initially slow atoms in a separate chamber. Our steady-state
high phase-space density MOT is an excellent starting point for a continuous
atom laser and dead-time free atom interferometers or clocks.Comment: 11 pages, 5 figure
Sisyphus Optical Lattice Decelerator
We experimentally demonstrate a variation on a Sisyphus cooling technique
that was proposed for cooling antihydrogen. In our implementation, atoms are
selectively excited to an electronic state whose energy is spatially modulated
by an optical lattice, and the ensuing spontaneous decay completes one Sisyphus
cooling cycle. We characterize the cooling efficiency of this technique on a
continuous beam of Sr, and compare it with radiation pressure based laser
cooling. We demonstrate that this technique provides similar atom number for
lower end temperatures, provides additional cooling per scattering event and is
compatible with other laser cooling methods. This method can be instrumental in
bringing new exotic species and molecules to the ultracold regime.Comment: 11 pages, 11 figure
The Role of Source Coherence in Atom Interferometery
The role of source cloud spatial coherence in a Mach-Zehnder type atom
interferometer is experimentally investigated. The visibility and contrast of a
Bose-Einstein condensate (BEC) and three thermal sources with varying spatial
coherence are compared as a function of interferometer time. At short times,
the fringe visibility of a BEC source approaches 100 % nearly independent of pi
pulse efficiency, while thermal sources have fringe visibilities limited to the
mirror efficiency. More importantly for precision measurement systems, the BEC
source maintains interference at interferometer times significantly beyond the
thermal source
80hk Momentum Separation with Bloch Oscillations in an Optically Guided Atom Interferometer
We demonstrate phase sensitivity in a horizontally guided,
acceleration-sensitive atom interferometer with a momentum separation of 80hk
between its arms. A fringe visibility of 7% is observed. Our coherent pulse
sequence accelerates the cold cloud in an optical waveguide, an inherently
scalable route to large momentum separation and high sensitivity. We maintain
coherence at high momentum separation due to both the transverse confinement
provided by the guide, and our use of optical delta-kick cooling on our
cold-atom cloud. We also construct a horizontal interferometric gradiometer to
measure the longitudinal curvature of our optical waveguide.Comment: 6 pages, 6 figure
A Bright Solitonic Matter-Wave Interferometer
We present the first realisation of a solitonic atom interferometer. A
Bose-Einstein condensate of atoms of rubidium-85 is loaded into a
horizontal optical waveguide. Through the use of a Feshbach resonance, the
-wave scattering length of the Rb atoms is tuned to a small negative
value. This attractive atomic interaction then balances the inherent
matter-wave dispersion, creating a bright solitonic matter wave. A Mach-Zehnder
interferometer is constructed by driving Bragg transitions with the use of an
optical lattice co-linear with the waveguide. Matter wave propagation and
interferometric fringe visibility are compared across a range of -wave
scattering values including repulsive, attractive and non-interacting values.
The solitonic matter wave is found to significantly increase fringe visibility
even compared with a non-interacting cloud.Comment: 6 pages, 4 figure
A Bose-condensed, simultaneous dual-species Mach-Zehnder atom interferometer
This paper presents the first realization of a simultaneous 87Rb-85Rb Mach-Zehnder atom interferometer with Bose-condensed atoms. A number of ambitious proposals for precise terrestrial and space based tests of the weak equivalence principle rely on suc
Optically guided linear Mach-Zehnder atom interferometer
We demonstrate a horizontal, linearly guided Mach-Zehnder atom interferometer in an optical waveguide. Intended as a proof-of-principle experiment, the interferometer utilizes a Bose-Einstein condensate in the magnetically insensitive F=1,mF=0 state of 87Rb as an acceleration-sensitive test mass. We achieve a modest sensitivity to acceleration of Δa=7×10-4 m/s2. Our fringe visibility is as high as 38% in this optically guided atom interferometer. We observe a time of flight in the waveguide of over 0.5 s, demonstrating the utility of our optical guide for future sensors
Gain-switched holmium-doped fibre laser
We demonstrate the first gain-switched, singly doped, single-mode holmium-doped silicate glass fibre laser that operates at 2.106 microm. Using a gain-switched 1.909-microm thulium-doped fibre laser as the pump source, output pulses of energy 3.2 microJ and pulse duration of 150 ns were generated at 80 kHz and slope efficiency of 44%. Pulse stacking within the holmium-doped fibre laser resulted in significantly shorter 70 ns pulses.Ka S. Wu, David Ottaway, Jesper Munch, David G. Lancaster, Shayne Bennetts, and Stuart D. Jackso
High-power 83 W holmium-doped silica fiber laser operating with high beam quality
Stuart D. Jackson, Alex Sabella, Alex Hemming, Shayne Bennetts, and David G. Lancaste
Efficient, polarised, gain-switched operation of a Tm-doped fibre laser
We present a monolithic, robustly polarised thulium fibre laser which produces pulses with 25 ns duration and energy of up to 35 µJ. A pulsed 1.55 μm source was used to gain switch the laser at repetition rates of up to 300 kHz, producing average powers of up to 8 W at 2.044 µm. To the best of our knowledge this is the highest power gain-switched thulium fibre laser and it is also the first with a linearly polarised output. The large repetition rate, pulse energy and average power will enable efficient energy extraction from a large mode-area, polarisation maintaining thulium fibre amplifier