1,416 research outputs found
Doppler-free frequency modulation spectroscopy of atomic erbium in a hollow cathode discharge cell
The erbium atomic system is a promising candidate for an atomic Bose-Einstein
condensate of atoms with a non-vanishing orbital angular momentum ()
of the electronic ground state. In this paper we report on the frequency
stabilization of a blue external cavity diode laser system on the 400.91
laser cooling transition of atomic erbium. Doppler-free saturation spectroscopy
is applied within a hollow cathode discharge tube to the corresponding
electronic transition of several of the erbium isotopes. Using the technique of
frequency modulation spectroscopy, a zero-crossing error signal is produced to
lock the diode laser frequency on the atomic erbium resonance. The latter is
taken as a reference laser to which a second main laser system, used for laser
cooling of atomic erbium, is frequency stabilized
Coherent excitation of ultracold atoms between ground and Rydberg states
This thesis describes the development of an experiment to study coherent population transfer between ground states, and between ground and Rydberg states, in ultracold atoms.
In order to study coherent transfer between hyperfine ground states a pair of phase stable Raman beams is required. Both beams are derived from a single master laser before being spatially separated into individual components using a novel Faraday filtering technique. The frequency dependent Faraday effect in an isotopically pure thermal vapour is exploited to rotate the plane of polarisation of each Raman component such that they may be separated using a polarising beam splitter. The Raman beams are applied to a sample of ultracold atoms and evidence of coherent population transfer is observed.
Rydberg states offer an ideal tool for electrometry; the electric field induced Rydberg energy level shift scales with the seventh power of the principle quantum number. Electromagnetically induced transparency (EIT) is used to map Rydberg energy level shifts onto a ground state transition. EIT in a thermal vapour cell also provides a novel method of stabilising the Rydberg coupling laser. The Rydberg energy level shift is highly sensitive to the electric field produced by adsorbates bonded to a nearby dielectric surface. These effects are found to be time dependent and can be eliminated if the electric field is applied transiently. The measured electric field is compared to that calculated by numerical solution of Laplace's equation; the bulk dielectric is found to have a strong effect on the local electric field experienced by the atoms.
The exaggerated properties of Rydberg states make these systems ideal for quantum information processing and precision electrometry
Atom interferometry gravity-gradiometer for the determination of the Newtonian gravitational constant G
We developed a gravity-gradiometer based on atom interferometry for the
determination of the Newtonian gravitational constant \textit{G}. The
apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme
for fast launch of two atomic clouds, was specifically designed to reduce
possible systematic effects. We present instrument performances and show that
the sensor is able to detect the gravitational field induced by source masses.
A discussion of projected accuracy for \textit{G} measurement using this new
scheme shows that the results of the experiment will be significant to
discriminate between previous inconsistent values.Comment: 9 pages,9 figures, Submitte
Generation of tuneable 589nm radiation as a Na guide star source using an optical parametric amplifier
We describe a 5.5W 589nm source based on a passively modelocked
Nd:YVO4 laser and a multi-stage Lithium Triborate optical
parametric amplifier seeded by a tuneable semiconductor laser. We show
this system can produce rapidly tuneable, transform-limited pulses in near
diffraction-limited beams at 589nm, useful for Na guide star applications.
The attraction of this scheme is that it can be assembled from commercially
available hardware and is readily scalable to high average powers
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Raman spectrometer
An improved Raman spectrometer is provided, having, in a preferred embodiment, a light source comprising an injection-locked laser diode array, a multipass cell to multiply the intensity of the light source, a dynamic gas sample focusing system, and an atomic vapor filter to remove the Rayleigh scattered light. The laser diode arrays are tuned to match an absorption band of the atomic vapor filter. The Raman scattered light passes virtually unattenuated through the filter to be recorded by a Fourier transform spectrometer or other spectrometer. This invention permits higher sensitivity and resolution than prior art Raman spectrometers, in particular permitting identification and measurement of Raman emissions that occur at low wave numbers. The light source of this invention can also be used in conjunction with optical notch filters and photodetectors to permit detection and measurement of preselected species in a sample.Board of Regents, University of Texas Syste
Solid-state laser system for laser cooling of Sodium
We demonstrate a frequency-stabilized, all-solid laser source at 589 nm with
up to 800 mW output power. The laser relies on sum-frequency generation from
two laser sources at 1064 nm and 1319 nm through a PPKTP crystal in a
doubly-resonant cavity. We obtain conversion efficiency as high as 2 W/W^2
after optimization of the cavity parameters. The output wavelength is tunable
over 60 GHz, which is sufficient to lock on the Sodium D2 line. The robustness,
beam quality, spectral narrowness and tunability of our source make it an
alternative to dye lasers for atomic physics experiments with Sodium atoms
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