Measurement of the ratio h/mRb and determination of the fine structure constant

Abstract

We present a review of the most precise determinations of the fine structure constant α which are obtained in different domains of physics. We describe the measurement of the ratio h/m Rb between the Plank constant and the mass of Rubidium atom which leads to a precise value of α which is very few dependent of the QED. Finally, we present a review of the different determinations of the von Kitzling constant R K .Nous présentons une revue des déterminations les plus précises de la constante de structure fine α qui sont obtenues dans différents domaines de la physique. Nous décrivons la mesure du rapport h/m Rb entre la constante de Planck et la masse de l'atome de rubidium qui conduità une valeur de α très précise et très peu dépendante de l'électrodynamique quantique. Finalement nous présentons une revue des différentes déterminations de la constante de von Kitzling R K .

CODATA Recommended Values of the Fundamental Physical Constants: 2010

“…The experiment of the LKB group from which the result given in Eq. ( 236) was obtained is described in the paper by Bouchendira et al (2011), the references cited therein; see also Cadoret et al (2009Cadoret et al ( , 2011Cadoret et al ( , 2008; Cladé et al (2010). It is worth noting, however, that the reduction in uncertainty of the 2008 result by over a factor of 7 was achieved by reducing the uncertainties of a number of individual components, especially those due to the alignment of beams, wave front curvature and Gouy phase, and the second order Zeeman effect.…”

Single-electron current sources: Toward a refined definition of the ampere

“…Propagation of the solitons promotes time correlation in the electron tunneling events, allowing the accuracy limitations of counting uncorrelated electrons presented above to be lifted. A proof-of-concept experimental realization has been presented by Bylander, Duty, and Delsing (2005). The array is terminated at the middle island of an SET, allowing for unity charge coupling, and a signal centered around frequency f c ¼ I=e is expected.…”

“…First are the tunnel junctions formed between the nearest-neighbor electrodes of the structure which enable the electron transfer between these electrodes, and the second is the possibility to control the electrostatic energy gaps by continuous variation of charges on the junctions (Averin and Likharev, 1986). The simplest way of varying the charges on the tunnel junctions continuously is by placing the electrodes in external electrical fields (Büttiker, 1987) that create continuously varying potential differences between the electrodes of the structure. Externally controlled gate voltages produced in this way can be used then to transfer individual electrons in the system of mesoscopic conductors.…”

“…The same dynamic would be obtained if real dc current I flows into a mesoscopic tunnel junction. In this case, correlated successive transfer of electrons one by one through the junction gives rise to ''single-electron tunneling'' oscillations (Averin and Likharev, 1986;Bylander, Duty, and Delsing, 2005) of voltage on the junction, @U=@ðenÞ ¼ eðnÀn g Þ=C AE , with frequency f related to the current by the fundamental equation…”

“…Therefore, the part of the Hamiltonian describing the tunneling of Cooper pairs should contain the terms accounting for the changes of the charge Q. Using the standard notation ÀE J =2 for the amplitude of Cooper-pair tunneling and including the charging energy (3), one obtains the Hamiltonian of a superconductor-insulator-superconductor (SIS) tunnel junction or, equivalently, Cooper-pair box in the following form (Averin, Zorin, and Likharev, 1985;Büttiker, 1987):…”