107 research outputs found
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
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
Proton-electron mass ratio from HD revisited
We present a new derivation of the proton-electron mass ratio from the
hydrogen molecular ion, HD. The derivation entails the adjustment of the
mass ratio in highly precise theory so as to reproduce accurately measured
ro-vibrational frequencies. This work is motivated by recent improvements of
the theory, as well as the more accurate value of the electron mass in the
recently published CODATA-14 set of fundamental constants, which justifies
using it as input data in the adjustment, rather than the proton mass value as
done in previous works. This leads to significantly different sensitivity
coefficients and, consequently, a different value and larger uncertainty margin
of the proton-electron mass ratio as obtained from HD
Precision Spectroscopy of Molecular Hydrogen Ions: Towards Frequency Metrology of Particle Masses
We describe the current status of high-precision ab initio calculations of
the spectra of molecular hydrogen ions (H_2^+ and HD^+) and of two experiments
for vibrational spectroscopy. The perspectives for a comparison between theory
and experiment at a level of 1 ppb are considered.Comment: 26 pages, 13 figures, 1 table, to appear in "Precision Physics of
Simple Atomic Systems", Lecture Notes in Physics, Springer, 200
High accuracy results for the energy levels of the molecular ions H2+, D2+ and HD+, up to J=2
We present a nonrelativistic calculation of the rotation-vibration levels of
the molecular ions H2+, D2+ and HD+, relying on the diagonalization of the
exact three-body Hamiltonian. The J=2 levels are obtained with a very high
accuracy of 10^{-14} a.u. (for most levels) representing an improvement by five
orders of magnitude over previous calculations. The accuracy is also improved
for the J=1 levels of H2+ and D2+ with respect to earlier works. Moreover, we
have computed the sensitivities of the energy levels with respect to the mass
ratios, allowing these levels to be used for metrological purposes.Comment: 11 page
Why three-body physics do not solve the proton radius puzzle
The possible involvement of weakly bound three-body systems in the muonic
hydrogen spectroscopy experiment [1], which could resolve the current
discrepancy between determinations of the proton radius, is investigated. Using
variational calculations with complex coordinate rotation, it is shown that the
ion, which was recently proposed as a possible candidate [2], has no
resonant states in the energy region of interest. QED level shifts are included
phenomenologically by including a Yukawa potential in the three-body Coulomb
Hamiltonian before diagonalization. It is also shown that the molecular
ion cannot play any role in the observed line
Polarization squeezing with cold atoms
We study the interaction of a nearly resonant linearly polarized laser beam
with a cloud of cold cesium atoms in a high finesse optical cavity. We show
theoretically and experimentally that the cross-Kerr effect due to the
saturation of the optical transition produces quadrature squeezing on both the
mean field and the orthogonally polarized vacuum mode. An interpretation of
this vacuum squeezing as polarization squeezing is given and a method for
measuring quantum Stokes parameters for weak beams via a local oscillator is
developed
Atomic physics: An almost lightless laser
Lasers are often described in terms of a light field circulating in an optical resonator system. Now a laser has been demonstrated in which the field resides primarily in the atomic medium that is used to generate the light
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