4,731 research outputs found
Dark resonances as a probe for the motional state of a single ion
Single, rf-trapped ions find various applications ranging from metrology to
quantum computation. High-resolution interrogation of an extremely weak
transition under best observation conditions requires an ion almost at rest. To
avoid line-broadening effects such as the second order Doppler effect or rf
heating in the absence of laser cooling, excess micromotion has to be
eliminated as far as possible. In this work the motional state of a confined
three-level ion is probed, taking advantage of the high sensitivity of observed
dark resonances to the trapped ion's velocity. Excess micromotion is controlled
by monitoring the dark resonance contrast with varying laser beam geometry. The
influence of different parameters such as the cooling laser intensity has been
investigated experimentally and numerically
Detection Techniques for Trapped Ions
Various techniques are used to detect the presence of charged particles
stored in electromagnetic traps, their energy, their mass, or their internal
states. Detection methods can rely on the variation of the number of trapped
particles (destructive methods) or the use of the ion's interaction with
electromagnetic radiation as a non-destructive tool to probe the trapped
particles. This review gives an introduction into various methods, discussing
the basic mode of operation completed by the description of recent
realizations
Prospects for measurement and control of the scattering length of metastable helium using photoassociation techniques
A numerical investigation of two-laser photoassociation (PA) spectroscopy on
spin-polarized metastable helium (He*) atoms is presented within the context of
experimental observation of the least-bound energy level in the scattering
potential and subsequent determination of the s-wave scattering length.
Starting out from the model developed by Bohn and Julienne [Phys. Rev. A
\textbf{60}, (1999) 414], PA rate coefficients are obtained as a function of
the parameters of the two lasers. The rate coefficients are used to simulate
one- and two-laser PA spectra. The results demonstrate the feasibility of a
spectroscopic determination of the binding energy of the least-bound level. The
simulated spectra may be used as a guideline when designing such an experiment,
whereas the model may also be employed for fitting experimentally obtained PA
spectra. In addition, the prospects for substantial modification of the He*
scattering length by means of optical Feshbach resonances are considered.
Several experimental issues relating to the numerical investigation presented
here are discussed.Comment: 9 pages, 7 figure
Spectroscopic determination of magnetic-field-dependent interactions in an ultracold Yb(3P2)-Li mixture
We present experimental results on the inelastic and elastic interspecies
interactions between ytterbium (Yb) in the metastable state
loaded into a deep optical lattice and spin polarized lithium (Li) in its
ground state. Focusing on the magnetic sublevel of
Yb(), bias magnetic fields between 20 G and 800 G are
investigated and significantly enhanced inelastic collision rates with high
magnetic fields are found. In addition, by direct spectroscopy of the Yb
Mott-insulator immersed in the Li Fermi gas an upper boundary of the background
scattering length of the Yb()-Li() system is estimated,
revealing the absence of useful Feshbach resonances. These observations are
qualitatively consistent with the theoretical calculations.Comment: 7 pages, 4 figure
Standard Model tests with trapped radioactive atoms
We review the use of laser cooling and trapping for Standard Model tests,
focusing on trapping of radioactive isotopes. Experiments with neutral atoms
trapped with modern laser cooling techniques are testing several basic
predictions of electroweak unification. For nuclear decay, demonstrated
trap techniques include neutrino momentum measurements from beta-recoil
coincidences, along with methods to produce highly polarized samples. These
techniques have set the best general constraints on non-Standard Model scalar
interactions in the first generation of particles. They also have the promise
to test whether parity symmetry is maximally violated, to search for tensor
interactions, and to search for new sources of time reversal violation. There
are also possibilites for exotic particle searches. Measurements of the
strength of the weak neutral current can be assisted by precision atomic
experiments using traps of small numbers of radioactive atoms, and sensitivity
to possible time-reversal violating electric dipole moments can be improved.Comment: 45 pages, 17 figures, v3 includes clarifying referee comments,
especially in beta decay section, and updated figure
Isotope shifts of natural Sr+ measured by laser fluorescence in a sympathetically cooled Coulomb crystal
We measured by laser spectroscopy the isotope shifts between
naturally-occurring even-isotopes of strontium ions for both the
5s\,\,^2S_{1/2}\to 5p\,\,^2P_{1/2} (violet) and the 4d\,\,^2D_{3/2}\to
5p\,\,^2P_{1/2} (infrared) dipole-allowed optical transitions. Fluorescence
spectra were taken by simultaneous measurements on a two-component Coulomb
crystal in a linear Paul trap containing -- laser-cooled Sr
ions. The isotope shifts are extracted from the experimental spectra by fitting
the data with the analytical solution of the optical Bloch equations describing
a three-level atom in interaction with two laser beams. This technique allowed
us to increase the precision with respect to previously reported data obtained
by optogalvanic spectroscopy or fast atomic-beam techniques. The results for
the 5s\,\,^2S_{1/2}\to 5p\,\,^2P_{1/2} transition are
MHz and MHz, in
agreement with previously reported measurements. In the case of the previously
unexplored 4d\,\,^2D_{3/2}\to 5p\,\,^2P_{1/2} transition we find
MHz and MHz. These
results provide more data for stringent tests of theoretical calculations of
the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the
identification and the addressing of Sr isotopes for ion frequency
standards or quantum-information-processing applications in the case of
multi-isotope ion strings.Comment: 19 pages; 5 figures; accepted on Phys. Rev. A (http://pra.aps.org/
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