1,942 research outputs found
BaH molecular spectroscopy with relevance to laser cooling
We describe a simple experimental apparatus for laser ablation of barium
monohydride (BaH) molecules and the study of their rovibrational spectra that
are relevant to direct laser cooling. We present a detailed analysis of the
properties of ablation plumes that can improve the understanding of surface
ablation and deposition technologies. A range of absorption spectroscopy and
collisional thermalization regimes has been studied. We directly measured the
Franck-Condon factor of the
transition.
Prospects for production of a high luminosity cryogenic BaH beam are outlined.
This molecule is a promising candidate for laser cooling and ultracold
fragmentation, both of which are precursors to novel experiments in many-body
physics and precision measurement.Comment: 11 pages, 10 figure
Precise study of asymptotic physics with subradiant ultracold molecules
Weakly bound molecules have physical properties without atomic analogues,
even as the bond length approaches dissociation. In particular, the internal
symmetries of homonuclear diatomic molecules result in formation of two-body
superradiant and subradiant excited states. While superradiance has been
demonstrated in a variety of systems, subradiance is more elusive due to the
inherently weak interaction with the environment. Here we characterize the
properties of deeply subradiant molecular states with intrinsic quality factors
exceeding via precise optical spectroscopy with the longest
molecule-light coherent interaction times to date. We find that two competing
effects limit the lifetimes of the subradiant molecules, with different
asymptotic behaviors. The first is radiative decay via weak magnetic-dipole and
electric-quadrupole interactions. We prove that its rate increases
quadratically with the bond length, confirming quantum mechanical predictions.
The second is nonradiative decay through weak gyroscopic predissociation, with
a rate proportional to the vibrational mode spacing and sensitive to
short-range physics. This work bridges the gap between atomic and molecular
metrology based on lattice-clock techniques, yielding new understanding of
long-range interatomic interactions and placing ultracold molecules at the
forefront of precision measurements.Comment: 12 pages, 6 figure
High-precision spectroscopy of ultracold molecules in an optical lattice
The study of ultracold molecules tightly trapped in an optical lattice can
expand the frontier of precision measurement and spectroscopy, and provide a
deeper insight into molecular and fundamental physics. Here we create, probe,
and image microkelvin Sr molecules in a lattice, and demonstrate
precise measurements of molecular parameters as well as coherent control of
molecular quantum states using optical fields. We discuss the sensitivity of
the system to dimensional effects, a new bound-to-continuum spectroscopy
technique for highly accurate binding energy measurements, and prospects for
new physics with this rich experimental system.Comment: 12 pages, 4 figure
Small-sized dichroic atomic vapor laser lock
Two, lightweight diode laser frequency stabilization systems designed for
experiments in the field are described. A significant reduction in size and
weight in both models supports the further miniaturization of measurement
devices in the field. Similar to a previous design, magnetic-field lines are
contained within a magnetic shield enclosing permanent magnets and a Rb cell,
so that these DAVLL systems may be used for magnetically sensitive instruments.
The Mini-DAVLL system (49 mm long) uses a vapor cell (20 mm long), and does not
require cell heaters. An even smaller Micro-DAVLL system (9mm long) uses a
micro-fabricated cell (3 mm square), and requires heaters. These new systems
show no degradation in performance with regard to previous designs, while
considerably reducing dimensions.Comment: 13 pages, 11 figures, published versio
Knots and Random Walks in Vibrated Granular Chains
We study experimentally statistical properties of the opening times of knots
in vertically vibrated granular chains. Our measurements are in good
qualitative and quantitative agreement with a theoretical model involving three
random walks interacting via hard core exclusion in one spatial dimension. In
particular, the knot survival probability follows a universal scaling function
which is independent of the chain length, with a corresponding diffusive
characteristic time scale. Both the large-exit-time and the small-exit-time
tails of the distribution are suppressed exponentially, and the corresponding
decay coefficients are in excellent agreement with the theoretical values.Comment: 4 pages, 5 figure
Unrestricted Hartree-Fock Analysis of SrCaRuO
We investigated the electronic and magnetic structure of
SrCaRuO () on the basis of the
double-layered three-dimensional multiband Hubbard model with spin-orbit
interaction. In our model, lattice distortion is implemented as the modulation
of transfer integrals or a crystal field. The most stable states are estimated
within the unrestricted Hartree-Fock approximation, in which the colinear spin
configurations with five different spin-quantization axes are adopted as
candidates. The obtained spin structures for some particular lattice
distortions are consistent with the neutron diffraction results for
CaRuO. Also, some magnetic phase transitions can occur due to
changes in lattice distortion. These results facilitate the comprehensive
understanding of the phase diagram of SrCaRuO.Comment: 16 pages, 7 figure
Generalized second Bargmann transforms associated with the hyperbolic Landau levels on the Poincar\'e disk
We deal with a family of generalized coherent states associated to the
hyperbolic Landau levels of the Schr\"odinger operator with uniform magnetic
field on the Poincar\'e disk. Their associated coherent state transforms
constitute a class of generalized second Bargmann transforms.Comment: 7 page
Lyman Alpha Emitters at Redshift 5.7 in the COSMOS Field
We present results from a narrow-band optical survey of a contiguous area of
1.95 deg^2, covered by the Cosmic Evolution Survey (COSMOS). Both optical
narrow-band (lambda_c = 8150 AA and Delta_lambda = 120 AA) and broad-band (B,
V, g', r', i', and z') imaging observations were performed with the Subaru
prime-focus camera, Suprime-Cam on the Subaru Telescope. We provide the largest
contiguous narrow-band survey, targetting Ly alpha emitters (LAEs) at z~5.7. We
find a total of 119 LAE candidates at z~5.7. Over the wide-area covered by this
survey, we find no strong evidence for large scale clustering of LAEs. We
estimate a star formation rate (SFR) density of ~7*10^-4 M_sun yr^-1 Mpc^-3 for
LAEs at z~5.7, and compare it with previous measurements.Comment: 26 pages, 19 figures. to appear in the ApJ Supplement COSMOS Special
Issu
- …