Abstract
One major change of the future revision of the International System of Units (SI) is a new definition of the ampere based on the elementary charge \emph{e}. Replacing the former definition based on Amp\`ere's force law will allow one to fully benefit from quantum physics to realize the ampere. However, a quantum realization of the ampere from \emph{e}, accurate to within $10^{-8}$ in relative value and fulfilling traceability needs, is still missing despite many efforts have been spent for the development of single-electron tunneling devices. Starting again with Ohm's law, applied here in a quantum circuit combining the quantum Hall resistance and Josephson voltage standards with a superconducting cryogenic amplifier, we report on a practical and universal programmable quantum current generator. We demonstrate that currents generated in the milliampere range are quantized in terms of $ef_\mathrm{J}$ ($f_\mathrm{J}$ is the Josephson frequency) with a measurement uncertainty of $10^{-8}$. This new quantum current source, able to deliver such accurate currents down to the microampere range, can greatly improve the current measurement traceability, as demonstrated with the calibrations of digital ammeters. Beyond, it opens the way to further developments in metrology and in fundamental physics, such as a quantum multimeter or new accurate comparisons to single electron pumps.
Highlights
Measurements rely on the International System of Units (SI) [1], which is a consistent system historically constructed on seven base units, namely, the meter (m), the kilogram, the second (s), the ampere (A), the kelvin (K), the mole, and the candela, all other units being formed as products of powers of the base units
Returning to Ohm’s law, which is the basis for the definition of the resistance unit, we developed a quantum current standard from the quantum Josephson voltage and Hall resistance standards that are combined in an original quantum circuit, with the aim of universality, accuracy, and simplicity [54]
This universal and versatile quantum current standard improves the accuracy of the current sources of 2 orders of magnitude compared to calibration and measurement capabilities (CMC)
Summary
Measurements rely on the International System of Units (SI) [1], which is a consistent system historically constructed on seven base units, namely, the meter (m), the kilogram (kg), the second (s), the ampere (A), the kelvin (K), the mole (mol), and the candela (cd), all other units being formed as products of powers of the base units. We report on a programmable quantum current generator (PQCG), linked to the elementary charge e, which is built from an application of Ohm’s law to quantum standards combined in an original quantum circuit [Fig. 1(c)] It is based on a current source locked, by means of a highly accurate cryogenic amplifier of gain G using a magnetic coupling, to a multiple or fraction value of a programmable quantum current standard (PQCS) used as a reference. The PQCG is able to implement the future ampere definition in terms of the elementary charge e with a target uncertainty of 10−8 This will rely on the adoption of the solid-state quantum theory in the planned new SI. Improvements in its realization are expected from the PQCG and the quantum circuit methods reported here
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
