46 research outputs found
Improvement by laser quenching of an "atom diode": a one-way barrier for ultra-cold atoms
Different laser devices working as ``atom diodes'' or ``one-way barriers''
for ultra-cold atoms have been proposed recently. They transmit ground state
level atoms coming from one side, say from the left, but reflect them when they
come from the other side. We combine a previous model, consisting of the
stimulated Raman adiabatic passage (STIRAP) from the ground to an excited state
and a state-selective mirror potential, with a localized quenching laser which
produces spontaneous decay back to the ground state. This avoids backwards
motion, provides more control of the decay process and therefore a more compact
and useful device.Comment: 6 page
Inelastic chaotic scattering on a Bose-Einstein condensate
We devise a microscopic scattering approach to probe the excitation spectrum
of a Bose-Einstein condensate. We show that the experimentally accessible
scattering cross section exhibits universal Ericson fluctuations, with
characteristic properties rooted in the underlying classical field equations.Comment: 11 pages, 5 figure
Matter wave pulses characteristics
We study the properties of quantum single-particle wave pulses created by
sharp-edged or apodized shutters with single or periodic openings. In
particular, we examine the visibility of diffraction fringes depending on
evolution time and temperature; the purity of the state depending on the
opening-time window; the accuracy of a simplified description which uses
``source'' boundary conditions instead of solving an initial value problem; and
the effects of apodization on the energy width.Comment: 11 pages, 11 figure
Atom Chips
Atoms can be trapped and guided using nano-fabricated wires on surfaces,
achieving the scales required by quantum information proposals. These Atom
Chips form the basis for robust and widespread applications of cold atoms
ranging from atom optics to fundamental questions in mesoscopic physics, and
possibly quantum information systems
Thermometry with spin-dependent lattices
We propose a method for measuring the temperature of strongly correlated
phases of ultracold atom gases confined in spin-dependent optical lattices. In
this technique, a small number of "impurity" atoms--trapped in a state that
does not experience the lattice potential--are in thermal contact with atoms
bound to the lattice. The impurity serves as a thermometer for the system
because its temperature can be straightforwardly measured using time-of-flight
expansion velocity. This technique may be useful for resolving many open
questions regarding thermalization in these isolated systems. We discuss the
theory behind this method and demonstrate proof-of-principle experiments,
including the first realization of a 3D spin-dependent lattice in the strongly
correlated regime.Comment: 22 pages, 8 figures v2: Several references added; Section on heating
rates updated to include dipole fluctuation terms; Section added on the
limitations of the proposed method. To appear in New Journal of Physic
Physics with Coherent Matter Waves
This review discusses progress in the new field of coherent matter waves, in
particular with respect to Bose-Einstein condensates. We give a short
introduction to Bose-Einstein condensation and the theoretical description of
the condensate wavefunction. We concentrate on the coherence properties of this
new type of matter wave as a basis for fundamental physics and applications.
The main part of this review treats various measurements and concepts in the
physics with coherent matter waves. In particular we present phase manipulation
methods, atom lasers, nonlinear atom optics, optical elements, interferometry
and physics in optical lattices. We give an overview of the state of the art in
the respective fields and discuss achievements and challenges for the future
Cooperative coupling of ultracold atoms and surface plasmons
Cooperative coupling between optical emitters and light fields is one of the
outstanding goals in quantum technology. It is both fundamentally interesting
for the extraordinary radiation properties of the participating emitters and
has many potential applications in photonics. While this goal has been achieved
using high-finesse optical cavities, cavity-free approaches that are broadband
and easy to build have attracted much attention recently. Here we demonstrate
cooperative coupling of ultracold atoms with surface plasmons propagating on a
plane gold surface. While the atoms are moving towards the surface they are
excited by an external laser pulse. Excited surface plasmons are detected via
leakage radiation into the substrate of the gold layer. A maximum Purcell
factor of is reached at an optimum distance of
from the surface. The coupling leads to the observation of
a Fano-like resonance in the spectrum.Comment: 9 pages, 4 figure
Quantitative Histomorphometry of the Healthy Peritoneum
The peritoneum plays an essential role in preventing abdominal frictions and adhesions and can be utilized as a dialysis membrane. Its physiological ultrastructure, however, has not yet been studied systematically. 106 standardized peritoneal and 69 omental specimens were obtained from 107 patients (0.1-60 years) undergoing surgery for disease not affecting the peritoneum for automated quantitative histomorphometry and immunohistochemistry. The mesothelial cell layer morphology and protein expression pattern is similar across all age groups. Infants below one year have a thinner submesothelium; inflammation, profibrotic activity and mesothelial cell translocation is largely absent in all age groups. Peritoneal blood capillaries, lymphatics and nerve fibers locate in three distinct submesothelial layers. Blood vessel density and endothelial surface area follow a U-shaped curve with highest values in infants below one year and lowest values in children aged 7-12 years. Lymphatic vessel density is much lower, and again highest in infants. Omental blood capillary density correlates with parietal peritoneal findings, whereas only few lymphatic vessels are present. The healthy peritoneum exhibits major thus far unknown particularities, pertaining to functionally relevant structures, and subject to substantial changes with age. The reference ranges established here provide a framework for future histomorphometric analyses and peritoneal transport modeling approaches. © 2016, EDP Science. All rights reserved