4 research outputs found
Quantum control, quantum information processing, and quantum-limited metrology with trapped ions
We briefly discuss recent experiments on quantum information processing using
trapped ions at NIST. A central theme of this work has been to increase our
capabilities in terms of quantum computing protocols, but we have also applied
the same concepts to improved metrology, particularly in the area of frequency
standards and atomic clocks. Such work may eventually shed light on more
fundamental issues, such as the quantum measurement problem.Comment: Proceedings of the International Conference on Laser Spectroscopy
(ICOLS), 10 pages, 5 figure
Remote frequency measurement of the 1S0-3P1 transition in laser cooled Mg-24
We perform Ramsey-Bord\'e spectroscopy on laser-cooled magnesium atoms in
free fall to measure the 1S0 \rightarrow 3P1 intercombination transition
frequency. The measured value of 655 659 923 839 730 (48) Hz is consistent with
our former atomic beam measurement (Friebe et al 2008 Phys. Rev. A 78 033830).
We improve upon the fractional accuracy of the previous measurement by more
than an order of magnitude to 7e-14. The magnesium frequency standard was
referenced to a fountain clock of the Physikalisch-Technische Bundesanstalt
(PTB) via a phase-stabilized telecom fiber link and its stability was
characterized for interrogation times up to 8000 s. The high temperature of the
atomic ensemble leads to a systematic shift due to the motion of atoms across
the spectroscopy beams. In our regime, this leads to a counterintuitive
reduction of residual Doppler shift with increasing resolution. Our theoretical
model of the atom-light interaction is in agreement with the observed effect
and allows us to quantify its contribution in the uncertainty budget.Comment: 16 pages, 8 figures. Accepted in New Journal of Physic
Theory and applications of atomic and ionic polarizabilities
Atomic polarization phenomena impinge upon a number of areas and processes in
physics. The dielectric constant and refractive index of any gas are examples
of macroscopic properties that are largely determined by the dipole
polarizability. When it comes to microscopic phenomena, the existence of
alkaline-earth anions and the recently discovered ability of positrons to bind
to many atoms are predominantly due to the polarization interaction. An
imperfect knowledge of atomic polarizabilities is presently looming as the
largest source of uncertainty in the new generation of optical frequency
standards. Accurate polarizabilities for the group I and II atoms and ions of
the periodic table have recently become available by a variety of techniques.
These include refined many-body perturbation theory and coupled-cluster
calculations sometimes combined with precise experimental data for selected
transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index
measurements in microwave cavities, ab initio calculations of atomic structures
using explicitly correlated wave functions, interferometry with atom beams, and
velocity changes of laser cooled atoms induced by an electric field. This
review examines existing theoretical methods of determining atomic and ionic
polarizabilities, and discusses their relevance to various applications with
particular emphasis on cold-atom physics and the metrology of atomic frequency
standards.Comment: Review paper, 44 page