7,437 research outputs found
Lasing on a narrow transition in a cold thermal strontium ensemble
Highly stable laser sources based on narrow atomic transitions provide a
promising platform for direct generation of stable and accurate optical
frequencies. Here we investigate a simple system operating in the
high-temperature regime of cold atoms. The interaction between a thermal
ensemble of Sr at mK temperatures and a medium-finesse cavity produces
strong collective coupling and facilitates high atomic coherence which causes
lasing on the dipole forbidden SP transition. We
experimentally and theoretically characterize the lasing threshold and
evolution of such a system, and investigate decoherence effects in an
unconfined ensemble. We model the system using a Tavis-Cummings model, and
characterize velocity-dependent dynamics of the atoms as well as the dependency
on the cavity-detuning.Comment: 9 pages, 7 figure
Non-linear Spectroscopy of Sr Atoms in an Optical Cavity for Laser Stabilization
We study the non-linear interaction of a cold sample of strontium-88 atoms
coupled to a single mode of a low finesse optical cavity in the so-called bad
cavity limit and investigate the implications for applications to laser
stabilization. The atoms are probed on the weak inter-combination line \lvert
5s^{2} \, ^1 \textrm{S}_0 \rangle \,-\, \lvert 5s5p \, ^3 \textrm{P}_1 \rangle
at 689 nm in a strongly saturated regime. Our measured observables include the
atomic induced phase shift and absorption of the light field transmitted
through the cavity represented by the complex cavity transmission coefficient.
We demonstrate high signal-to-noise-ratio measurements of both quadratures -
the cavity transmitted phase and absorption - by employing FM spectroscopy
(NICE-OHMS). We also show that when FM spectroscopy is employed in connection
with a cavity locked to the probe light, observables are substantially modified
compared to the free space situation where no cavity is present. Furthermore,
the non-linear dynamics of the phase dispersion slope is experimentally
investigated and the optimal conditions for laser stabilization are
established. Our experimental results are compared to state-of-the-art cavity
QED theoretical calculations.Comment: 7 pages, 4 figure
Playing Muller Games in a Hurry
This work studies the following question: can plays in a Muller game be
stopped after a finite number of moves and a winner be declared. A criterion to
do this is sound if Player 0 wins an infinite-duration Muller game if and only
if she wins the finite-duration version. A sound criterion is presented that
stops a play after at most 3^n moves, where n is the size of the arena. This
improves the bound (n!+1)^n obtained by McNaughton and the bound n!+1 derived
from a reduction to parity games
Experimental Evidence for Quantum Interference and Vibrationally Induced Decoherence in Single-Molecule Junctions
We analyze quantum interference and decoherence effects in single-molecule
junctions both experimentally and theoretically by means of the mechanically
controlled break junction technique and density-functional theory. We consider
the case where interference is provided by overlapping quasi-degenerate states.
Decoherence mechanisms arising from the electronic-vibrational coupling
strongly affect the electrical current flowing through a single-molecule
contact and can be controlled by temperature variation. Our findings underline
the all-important relevance of vibrations for understanding charge transport
through molecular junctions.Comment: 5 pages, 4 figure
Co-Occurrence and Characteristics of Patients With Axial Spondyloarthritis Who Meet Criteria for Fibromyalgia : Results From a UK National Register
The British Society for Rheumatology (BSR) Biologics Register in Ankylosing Spondylitis is funded by the BSR and they have receive funds for this from Pfizer, AbbVie and UCB. These companies receive advance copies of manuscripts and can provide comments but have no input into determining the topics for analysis, publication and no input into the work involved in this analysis. This analysis is part-funded by Arthritis Research UK (Grant No: 21378)Peer reviewedPublisher PD
Specific Contributions of Ventromedial, Anterior Cingulate, and Lateral Prefrontal Cortex for Attentional Selection and Stimulus Valuation
Functional clusters of neurons in the monkey prefrontal and anterior cingulate cortex are involved in guiding attention to the most valuable objects in a scene
From extended phase space dynamics to fluid theory
We derive a fluid theory for spin-1/2 particles starting from an extended
kinetic model based on a spin-projected density matrix formalism. The evolution
equation for the spin density is found to contain a pressure-like term. We give
an example where this term is important by looking at a linear mode previously
found in a spin kinetic model.Comment: 4 page
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