266 research outputs found
Analytical matrix elements of the Uehling potential in three-body systems, and applications to exotic molecules
Exact analytical expressions for the matrix elements of the Uehling potential
in a basis of explicitly correlated exponential wave functions are presented.
The obtained formulas are then used to compute with an improved accuracy the
vacuum polarization correction to the binding energy of muonic and pionic
molecules, both in a first-order perturbative treatment and in a
nonperturbative approach. The first resonant states lying below the n=2
threshold are also studied, by means of the stabilization method with a real
dilatation parameter
Theoretical transition frequencies beyond 0.1 ppb accuracy in H, HD, and antiprotonic helium
We present improved theoretical calculations of transition frequencies for
the fundamental transitions in the
hydrogen molecular ions H and HD with a relative uncertainty
and for the two-photon transitions in the antiprotonic helium
atom with a relative uncertainty . To do that, the one-loop
self-energy correction of order is derived in the two
Coulomb center approximation, and numerically evaluated in the case of the
aforementioned transitions. The final results also include a complete set of
other spin-independent corrections of order . The leading order
corrections of are also considered
that allows to estimate a magnitude of yet uncalculated contributions.Comment: 10 pages, 2 figure, to be submitted to PR
One-loop vacuum polarization at order for the two center problem
We present calculations of the one-loop vacuum polarization contribution
(Uehling potential) for the two-center problem in the NRQED formalism. The
cases of hydrogen molecular ions () as well as antiprotonic helium
(, ) are considered. Numerical results of the vacuum
polarization contribution at order for the fundamental transitions
in H and HD are presented.Comment: 6 pages, 2 figues, submitted to PR
Calculation of the relativistic Bethe logarithm in the two-center problem
We present a variational approach to evaluate relativistic corrections of
order \alpha^2 to the Bethe logarithm for the ground electronic state of the
Coulomb two center problem. That allows to estimate the radiative contribution
at m\alpha^7 order in molecular-like three-body systems such as hydrogen
molecular ions H_2^+ and HD^+, or antiprotonic helium atoms. While we get 10
significant digits for the nonrelativistic Bethe logarithm, calculation of the
relativistic corrections is much more involved especially for small values of
bond length R. We were able to achieve a level of 3-4 significant digits
starting from R=0.2 bohr, that will allow to reach 10^{-10} relative
uncertainty on transition frequencies.Comment: 19 pages, 5 tables, 7 figure
A new vibrational level of the H molecular ion
A new state of the H molecular ion with binding energy of
1.09 a.u. below the first dissociation limit is predicted, using
highly accurate numerical nonrelativistic quantum calculations. It is the first
L=0 excited state, antisymmetric with respect to the exchange of the two
protons. It manifests itself as a huge p-H scattering length of
Bohr radii.Comment: 6 pages + 3 figure
Hydrogen molecular ions for improved determination of fundamental constants
The possible use of high-resolution rovibrational spectroscopy of the
hydrogen molecular ions H + 2 and HD + for an independent determination of
several fundamental constants is analyzed. While these molecules had been
proposed for metrology of nuclear-to-electron mass ratios, we show that they
are also sensitive to the radii of the proton and deuteron and to the Rydberg
constant at the level of the current discrepancies colloquially known as the
proton size puzzle. The required level of accuracy, in the 10 --12 range, can
be reached both by experiments, using Doppler-free two-photon spectroscopy
schemes, and by theoretical predictions. It is shown how the measurement of
several well-chosen rovibrational transitions may shed new light on the
proton-radius puzzle, provide an alternative accurate determination of the
Rydberg constant, and yield new values of the proton-to-electron and
deuteron-to-proton mass ratios with one order of magnitude higher precision
Optical nonlinear dynamics with cold atoms in a cavity
This paper presents the nonlinear dynamics of laser cooled and trapped cesium
atoms placed inside an optical cavity and interacting with a probe light beam
slightly detuned from the 6S1/2(F=4) to 6P3/2(F=5) transition. The system
exhibits very strong bistability and instabilities. The origin of the latter is
found to be a competition between optical pumping and non-linearities due to
saturation of the optical transition.Comment: 6 pages, 7 figures, LaTe
Raman laser spectroscopy of Wannier Stark states
Raman lasers are used as a spectroscopic probe of the state of atoms confined
in a shallow 1D vertical lattice. For long enough laser pulses, resolved
transitions in the bottom band of the lattice between Wannier Stark states
corresponding to neighboring wells are observed. Couplings between such states
are measured as a function of the lattice laser intensity and compared to
theoretical predictions, from which the lattice depth can be extracted. Limits
to the linewidth of these transitions are investigated. Transitions to higher
bands can also be induced, as well as between transverse states for tilted
Raman beams. All these features allow for a precise characterization of the
trapping potential and for an efficient control of the atoms external degrees
of freedom
Narrow-line phase-locked quantum cascade laser in the 9.2 micron range
We report on the operation of a 50 mW continuous wave quantum cascade laser
(QCL) in the 9.2 micrometer range, phase locked to a single mode CO2 laser with
a tunable frequency offset. The wide free running emission spectrum of the QCL
(3-5 MHz) is strongly narrowed down to the kHz range making it suitable for
high resolution molecular spectroscopy.Comment: 4 page
State labelling Wannier-Stark atomic interferometers
Using cold 87Rb atoms trapped in a 1D-optical lattice, atomic interferometers
involving coherent superpositions between different Wannier-Stark atomic states
are realized. Two di fferent kinds of trapped interferometer schemes are
presented: a Ramsey-type interferometer sensitive both to clock frequency and
external forces, and a symmetric accordion-type interferometer, sensitive to
external forces only. We evaluate the limits in terms of sensitivity and
accuracy of those schemes and discuss their application as force sensors. As a
first step, we apply these interferometers to the measurement of the Bloch
frequency and the demonstration of a compact gravimeter.Comment: 11 page
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