9 research outputs found
Three-dimensional atom localization by laser fields in a four-level tripod system
We present a scheme for high-precision three-dimensional (3D) localization by the measurement of the atomic-level population. The scheme is applied to a four-level tripod-type atom coupled by three strong standing waves and a probe running wave. As a result, the atom can be localized in volumes that are substantially smaller than a cubic optical wavelength, which is achieved by the increase of standing-wave intensities. The upper-level distribution depends crucially on the atom-field coupling and it forms 3D periodic structures composed of spheres, hourglasses, bowls, donuts, or deformed barrels.</p
Efficient Two-dimensional Subrecoil Raman Cooling of Atoms in a Tripod Configuration
We present an efficient method for subrecoil cooling of neutral atoms by
applying Raman cooling in 2D to a four-level tripod-system. The atoms can be
cooled simultaneously in two directions using only three laser beams. We
describe the cooling process with a simple model showing that the momentum
distribution can be rapidly narrowed to velocity spread down to
, corresponding to effective temperature equal to
. This method opens new possibilities for cooling of neutral
atoms.Comment: 6 pages, 3 figure
Robust two-dimensional subrecoil Raman cooling by adiabatic transfer in a tripod atomic system
We demonstrate two-dimensional robust Raman cooling in a four-level tripod
system, in which velocity-selective population transfer is achieved by a STIRAP
pulse. In contrast to basic 2D Raman cooling with square envelope pulses [Phys.
Rev. A 83, 023407 (2011)], the technique presented here allows for a wide
variation in the pulse duration and amplitude once the adiabaticity criterion
is satisfied. An efficient population transfer together with attaining of a
narrow spread of the resonant-velocity group leads to the narrowing of the
velocity-distribution spread down to , corresponding to an
effective temperature equal to . This robust method opens
new possibilities for cooling of neutral atoms.Comment: 8 pages, 3 figure
Pervasive head-to-tail insertions of DNA templates mask desired CRISPR-Cas9-mediated genome editing events
CRISPR-Cas9-mediated homology-directed DNA repair is the method of choice for precise gene editing in a wide range of model organisms, including mouse and human. Broad use by the biomedical community refined the method, making it more efficient and sequence specific. Nevertheless, the rapidly evolving technique still contains pitfalls. During the generation of six different conditional knockout mouse models, we discovered that frequently (sometimes solely) homology-directed repair and/or nonhomologous end joining mechanisms caused multiple unwanted head-to-tail insertions of donor DNA templates. Disturbingly, conventionally applied PCR analysis, in most cases, failed to identify these multiple integration events, which led to a high rate of falsely claimed precisely edited alleles. We caution that comprehensive analysis of modified alleles is essential and offer practical solutions to correctly identify precisely edited chromosomes