407 research outputs found
Compact solid-state laser source for 1S-2S spectroscopy in atomic hydrogen
We demonstrate a novel compact solid-state laser source for high-resolution
two-photon spectroscopy of the transition in atomic hydrogen. The
source emits up to 20 mW at 243 nm and consists of a 972 nm diode laser, a
tapered amplifier, and two doubling stages. The diode laser is actively
stabilized to a high-finesse cavity. We compare the new source to the stable
486 nm dye laser used in previous experiments and record 1S-2S spectra using
both systems. With the solid-state laser system we demonstrate a resolution of
the hydrogen spectrometer of 6 \times 10^{11} which is promising for a number
of high-precision measurements in hydrogen-like systems
Applications of Integrated Magnetic Microtraps
Lithographically fabricated circuit patterns can provide magnetic guides and
microtraps for cold neutral atoms. By combining several such structures on the
same ceramic substrate, we have realized the first ``atom chips'' that permit
complex manipulations of ultracold trapped atoms or de Broglie wavepackets. We
show how to design magnetic potentials from simple conductor patterns and we
describe an efficient trap loading procedure in detail. Applying the design
guide, we describe some new microtrap potentials, including a trap which
reaches the Lamb-Dicke regime for rubidium atoms in all three dimensions, and a
rotatable Ioffe-Pritchard trap, which we also demonstrate experimentally.
Finally, we demonstrate a device allowing independent linear positioning of two
atomic clouds which are very tightly confined laterally. This device is well
suited for the study of one-dimensional collisions.Comment: 10 pages, 17 figure
Adaptive dual-comb spectroscopy in the green region
Dual-comb spectroscopy is extended to the visible spectral range with a
set-up based on two frequency-doubled femtosecond ytterbium-doped fiber lasers.
The dense rovibronic spectrum of iodine around 19240 cm-1 is recorded within 12
ms at Doppler-limited resolution with a simple scheme that only uses
free-running femtosecond lasers
Laser frequency combs for astronomical observations
A direct measurement of the universe's expansion history could be made by
observing in real time the evolution of the cosmological redshift of distant
objects. However, this would require measurements of Doppler velocity drifts of
about 1 centimeter per second per year, and astronomical spectrographs have not
yet been calibrated to this tolerance. We demonstrate the first use of a laser
frequency comb for wavelength calibration of an astronomical telescope. Even
with a simple analysis, absolute calibration is achieved with an equivalent
Doppler precision of approximately 9 meters per second at about 1.5 micrometers
- beyond state-of-the-art accuracy. We show that tracking complex, time-varying
systematic effects in the spectrograph and detector system is a particular
advantage of laser frequency comb calibration. This technique promises an
effective means for modeling and removal of such systematic effects to the
accuracy required by future experiments to see direct evidence of the
universe's putative acceleration.Comment: Science, 5th September 2008. 18 pages, 7 figures (7 JPG files),
including Supporting Online Material. Version with higher resolution figures
available at http://astronomy.swin.edu.au/~mmurphy/pub.htm
Observing the Profile of an Atom Laser Beam
We report on an investigation of the beam profile of an atom laser extracted
from a magnetically trapped Rb Bose-Einstein condensate. The transverse
momentum distribution is magnified by a curved mirror for matter waves and a
momentum resolution of 1/60 of a photon recoil is obtained. We find the
transverse momentum distribution to be determined by the mean-field potential
of the residing condensate, which leads to a non-smooth transverse density
distribution. Our experimental data are compared with a full 3D simulation of
the output coupling process and we find good agreement.Comment: 4 pages, 4 figure
Injection Locking of a Trapped-Ion Phonon Laser
We report on injection locking of optically excited mechanical oscillations of a single, trapped ion. The injection locking dynamics are studied by analyzing the oscillator spectrum with a spatially selective Fourier transform technique and the oscillator phase with stroboscopic imaging. In both cases we find excellent agreement with theory inside and outside the locking range. We attain injection locking with forces as low as 5(1)Ă10^(-24)ââN so this system appears promising for the detection of ultraweak oscillating forces
Frequency Metrology on single trapped ions in the weak binding limit: The 3s1/2-3p3/2 transition in 24-Mg+
We demonstrate a method for precision spectroscopy on trapped ions in the
limit of unresolved motional sidebands. By sympathetic cooling of a chain of
crystallized ions we suppress adverse temperature variations induced by the
spectroscopy laser that usually lead to a distorted line profle and obtain a
Voigt profile with negligible distortions. We applied the method to measure the
absolute frequency of the astrophysically relevant D2 transition in single
24-Mg+ ions and find 1072082934.33(16)MHz, a nearly 400fold improvement over
previous results. Further, we find the excited state lifetime to be 3.84(10)
ns.Comment: 4 pages, 5 figure
Comb-calibrated solar spectroscopy through a multiplexed single-mode fiber channel
We investigate a new scheme for astronomical spectrograph calibration using
the laser frequency comb at the Solar Vacuum Tower Telescope on Tenerife. Our
concept is based upon a single-mode fiber channel, that simultaneously feeds
the spectrograph with comb light and sunlight. This yields nearly perfect
spatial mode matching between the two sources. In combination with the absolute
calibration provided by the frequency comb, this method enables extremely
robust and accurate spectroscopic measurements. The performance of this scheme
is compared to a sequence of alternating comb and sunlight, and to absorption
lines from Earth's atmosphere. We also show how the method can be used for
radial-velocity detection by measuring the well-explored 5-minute oscillations
averaged over the full solar disk. Our method is currently restricted to solar
spectroscopy, but with further evolving fiber-injection techniques it could
become an option even for faint astronomical targets.Comment: 21 pages, 11 figures. A video abstract for this paper is available on
youtube. For watching the video, please follow
https://www.youtube.com/watch?v=oshdZgrt89I . The video abstract is also
available for streaming and download on the related article website of New
Journal of Physic
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