Vortrag

Datum:		8.11.2006
Uhrzeit:		11:00 Uhr
Ort:		PTB Berlin, Hermann-von-Helmholtz-Bau, Hörsaal
Titel:		Quantum metrological triangle experiment using a ccc as an ultra-low-current amplifier
Vortragender:		Dr. François Piquemal Fundamental Electrical Metrology Department of the LNE

Abstract:		Following the ac Josephson effect (JE) and the quantum Hall effect (QHE) which are now widely used to maintain the volt and the ohm, the single electron tunneling (SET) effect could be a basis for a quantum standard of current. From theory the constant involved in SET is presumed the electron charge e. Similarly, the constants KJ and RK provided by JE and QHE should correspond to 2e/h and h/e² respectively. Testing these theoretical presumptions presents a great interest especially at an accuracy level as high as one part in 10⁸. This is the ultimate goal of the quantum metrological triangle experiment. At LNE, this consists in the direct comparison of the voltage supplied by a Josephson junction array to the Hall voltage of a QHE device crossed by a current delivered by a SET current source. The very low value (a few pA) of the quantized current issued from the electron pump (the more promising SET device) is amplified by means of a cryogenic current comparator. The talk will first present foundations of the metrological triangle experiment. Then some experimental set-up will be described along with expected uncertainties in both the short and long terms. A progress report of SET measurements carried out at LNE will be finally given
Veranstalter:		Abteilung 7