Christian J. Bordé

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Over the past 40 years, a number of discoveries in quantum physics have completely transformed our vision of fundamental metrology. This revolution starts with the frequency stabilization of lasers using saturation spectroscopy and the redefinition of the metre by fixing the velocity of light c. Today, the trend is to redefine all SI base units from(More)
We present a second–quantized field theory of massive spin one–half particles or antiparticles in the presence of a weak gravitational field treated as a spin two external field in a flat Minkowski background. We solve the difficulties which arise from the derivative coupling and we are able to introduce an interaction picture. We derive expressions for the(More)
In ref. 1 the authors present a re-interpretation of atom interferometry experiments published a decade ago. They now consider the atom interferometry experiments as a measurement of the gravitational redshift on the quantum clock operating at the Compton frequency omega(C) = mc(2)/ approximately 2pi x 3.0 x 10(25) Hz, where m is the caesium (Cs) atom rest(More)
Doppler-free high-resolution spectroscopy is applied to molecular iodine at 532 nm by Nd:YAG lasers. The main hyperfine components as well as the crossover lines are measured for R(56)32-0 and P(54)32-0 transitions by heterodyne beating of two I 2-stabilized lasers. The measured hyperfine splittings including both main and crossover lines are fitted to a(More)
Atom interferometers allow the measurement of the acceleration of freely falling atoms with respect to an experimental platform at rest on Earth’s surface. Such experiments have been used to test the universality of free fall by comparing the acceleration of the atoms to that of a classical freely falling object. In a recent paper, Müller, Peters and Chu [A(More)
This special issue is entirely devoted to the experimental determination of Boltzmann’s constant k (also frequently noted kB to avoid the confusion with an electromagnetic wave vector modulus). Named after Ludwig Boltzmann, Austrian physicist of the XIXth century [1844–1906], this fundamental constant acts as a conversion factor from thermodynamic(More)
We report experimental evidence for the splitting of E levels in SiF4, which are degenerate in parity as far as the rovibrational Hamiltonian solely is concerned. The parity degeneracy of rovibrational levels is in fact lifted by hyperfine interactions, even though the associated total spin is I ­ 0. We compare this situation with that in other molecules(More)
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