24 research outputs found
Longitudinal Atomic Beam Spin Echo Experiments: A possible way to study Parity Violation in Hydrogen
We discuss the propagation of hydrogen atoms in static electric and magnetic
fields in a longitudinal atomic beam spin echo (lABSE) apparatus. Depending on
the choice of the external fields the atoms may acquire both dynamical and
geometrical quantum mechanical phases. As an example of the former, we show
first in-beam spin rotation measurements on atomic hydrogen, which are in
excellent agreement with theory. Additional calculations of the behaviour of
the metastable 2S states of hydrogen reveal that the geometrical phases may
exhibit the signature of parity-(P-)violation. This invites for possible future
lABSE experiments, focusing on P-violating geometrical phases in the lightest
of all atoms.Comment: 6 pages, 4 figure
Enhancement of Blackbody Friction due to the Finite Lifetime of Atomic Levels
The thermal friction force acting on an atom moving relative to a thermal
photon bath is known to be proportional to an integral over the imaginary part
of the frequency-dependent atomic (dipole) polarizability. Using a numerical
approach, we find that blackbody friction on atoms either in dilute
environments or in hot ovens is larger than previously thought by orders of
magnitude. This enhancement is due to far off-resonant driving of transitions
by low-frequency thermal radiation. At typical temperatures, the blackbody
radiation maximum lies far below the atomic transition wavelengths.
Surprisingly, due to the finite lifetime of atomic levels, which gives rise to
Lorentzian line profiles, far off-resonant excitation leads to the dominant
contribution to the blackbody friction.Comment: 4 pages; RevTe
Two-dimensional simulation of quantum reflection
A propagation method for the scattering of a quantum wave packet from a potential surface is presented. It is used to model the quantum reflection of single atoms from a corrugated (metallic) surface. Our numerical procedure works well in two spatial dimensions requiring only reasonable amounts of memory and computing time. The effects of the surface corrugation on the reflectivity are investigated via simulations with a paradigm potential. These indicate that our approach should allow for future tests of realistic, effective potentials obtained from theory in a quantitative comparison to experimental data
The Structure of C2H4 Clusters from Theoretical Interaction Potentials and Vibrational Predissociation Data
Optimized geometries and binding energies are calculated for ethene (ethylene) dimers, trimers, and tetramers based on a pairwise additive dimer potential. From these results intermolecular frequencies and relative abundancies (catchment areas) of the different isomers are obtained and compared with the results of accurate measurements of the photodissociation upon absorption of one photon of a CO2 laser in the region of the ν7 monomer absorption band at 949 cm-1. The clusters are size selected in a scattering experiment and show for a cluster size from n=2 to n=6 a frequency maximum shifted by 3 cm-1 to the blue compared with the monomer. The result is explained by the predominance of chains and chain-like structures of the clusters in the photodissociation process. The chains consist of cross-like dimer sub-units
Atom Interferometers
Interference with atomic and molecular matter waves is a rich branch of
atomic physics and quantum optics. It started with atom diffraction from
crystal surfaces and the separated oscillatory fields technique used in atomic
clocks. Atom interferometry is now reaching maturity as a powerful art with
many applications in modern science. In this review we first describe the basic
tools for coherent atom optics including diffraction by nanostructures and
laser light, three-grating interferometers, and double wells on AtomChips. Then
we review scientific advances in a broad range of fields that have resulted
from the application of atom interferometers. These are grouped in three
categories: (1) fundamental quantum science, (2) precision metrology and (3)
atomic and molecular physics. Although some experiments with Bose Einstein
condensates are included, the focus of the review is on linear matter wave
optics, i.e. phenomena where each single atom interferes with itself.Comment: submitted to Reviews of Modern Physic
Probing the short range spin dependent interactions by polarized 3 He atom beams
Experiments using polarized 3He atom beams to search for short range spin dependent forces are proposed. High intensity, high polarization, small beam size 3He atom beams have been successfully produced and used in surface science researches. By incorporating background reduction designs as combination shielding by µ-metal and superconductor and double beam paths, the precision of spin rotation angle per unit length could be improved by a factor of ~104. By this precision, in combination with a high density and low magnetic susceptibility sample source mass, and reversing one beam path if necessary, sensitivities on three different types of spin dependent interactions could be improved by as much as ~102 to ~108 over the current experiments at the millimeter range
Massive spin-momentum entanglement measured in an atomic beam spin echo experiment
In this paper we present an experiment performed with an atomic beam spin echo
interferometer, in which massive intraparticle entanglement is demonstrated. In the
longitudinal Stern-Gerlach arrangement the nuclear spin and linear momentum of
3He particles are inextricably linked, such that the overall system state
cannot be written as the tensor product of the corresponding Hilbert spaces. The measured
data show maximal entanglement between ℋI
and ℋp. This hybrid system of one quantum and one classical
degree of freedom is a textbook example of entanglement between discrete and continuous
observables