Argument for a direct realization of the quantum metrological triangle

Abstract

The quantum metrological triangle experiment, which is under development at the Bureau National de Métrologie-Laboratoire Central des Industries Électriques (BNM-LCIE), consists of applying Ohm's law directly to the quantities related to the single-electron tunnelling (SET) effect, the ac Josephson effect (JE) and the quantum Hall effect (QHE). The goal of this experiment is to test, at a significant level of uncertainty of about 1 part in 108, the coherence of the constants involved in these three quantum phenomena: the Josephson constant KJ, expected to correspond to the ratio 2e/h (where e is the elementary charge and h the Planck constant); the von Klitzing constant RK, in relation to the quantum resistance h/e2; and a new constant QX, defined here as the estimate of e. Moreover, realization of the metrological triangle experiment, combined with the experiment being developed at the NIST aimed at charging a capacitor by means of a SET pump, will give information liable to be taken into account in future adjustments of the fundamental constants without requiring any hypothesis regarding the physical phenomena involved. The combination of these two experiments should yield a new value of RK in ohms of the International System of Units (SI). The broad outlines of our experimental set-up are given, along with the expected uncertainties in both the short and long terms.

NbSi nanowire quantum phase-slip circuits: dc supercurrent blockade, microwave measurements, and thermal analysis

“…This requires that the output from a quantum current standard should be accurate to better than 1 part in 10 7 and that the magnitude of the current should exceed 100 pA to avoid an excessively long integration time. 6,9,10 The present state of the art in GaAs tunable barrier electron pumps is a current of magnitude 150 pA with an experimentally demonstrated current accuracy better than 1.2 parts per million and evidence based on modeling that the true accuracy approaches 1 part in 10 8 . 5 A quantum current standard based on QPS arises from the exact duality between the Josephson junction and the quantum-phase-slip junction (QPSJ).…”

TRIMET : fermeture du triangle métrologique quantique à un niveau d'incertitude relative de 10–6

“…Pour cela, il a été nécessaire, d'une part, de poursuivre les efforts dans la maîtrise de l'effet Josephson et de l'effet Hall quantique pour les éta-lons primaires de tension et de résistance, et d'autre part de développer un étalon de courant fondé sur un troisième effet quantique : l'effet tunnel mono-électronique (voir § 2) [10]. Cette stratégie permet au LNE d'avoir une position incontournable dans les débats actuels sur la dé-finition d'un ampère « quantique » et ainsi de mettre en oeuvre l'expérience du triangle métrologique quantique (TMQ) [11][12][13]. L'objectif de cette expérience est d'approfondir nos connaissances sur les trois effets quantiques afin de pouvoir définir, à terme, l'ensemble des unités électriques à partir de h et e, charge élémentaire.…”

SQUIDs for Standards and Metrology

“…The aim of the QMT experiments is to check the consistency of the constants involved in the three quantum phenomena which are strongly believed to provide the free space values of h/e 2 , 2e/h and e. In practice, the experiments determine the dimensionless product R K K J Q X , expected to be equal to 2, where the constant Q X is defined as an estimate of the elementary charge, Q X = e| SET , by analogy to the definitions of Josephson and von Klitzing constants, K J = 2e/h | JE and R K = h/e 2 | QHE [74,75]. Checking the equality R K K J Q X = 2 with an uncertainty of one part in 10 8 will be a relevant test of the validity of the three theories.…”

“…Taking into account the relationships given by acJE, QHE and SET and using the same notation as in [74], R K = h/e 2 (1 + r), K J = 2e/h (1 + k) and Q X = e (1 + q), one finds that Eq. (9.28) becomes s = (n/2)(i/G CCC )(f J /f SET ) (9.29) where s = r +q + k to first order, and f J and f SET are the irradiation and operation frequencies of the JJA and SET devices, respectively.…”

“…An experimental set-up for testing the QMT is sketched in Figure 9.14. The current amplifier is composed of a type I CCC of high winding ratio, G CCC = N 1 /N 2 , a dc SQUID with low white noise level and low corner frequency f c , and a secondary current source, servo-controlled by the SQUID in such a way that the latter works at null magnetic flux [74]. In order to minimize the contribution from 1/f flicker noise, the polarity of the current to be amplified is periodically reversed.…”