Novel digital impedance bridges for the realization of the farad from graphene quantum standards

In the International System of Units, a realization of the impedance units is the quantum Hall effect, a macroscopic quantum phenomenon that produces quantized resistance values. Established experiments employ individual GaAs devices [1], but research is ongoing on novel materials such as graphene, which allows the realization of the units with relaxed experimental conditions. Furthermore, novel digital impedance bridges allow the implementation of simple traceability chains. In the framework of the European EMPIR project 18SIB07 GIQS (Graphene Impedance Quantum Standards), an affordable and easy-to-operate impedance standard combining novel digital impedance bridges and graphene quantum standards has been developed. An onsite comparison of an electronic and a Josephson impedance bridges developed at INRIM (Istituto Nazionale di Ricerca Metrologica, Italy) and PTB (Physikalisch-Technische Bundesanstalt, Germany), respectively, were organized for their mutual validation and to assess their performance in the realization of the farad.Measurements of temperature-controlled impedance standards and of a graphene quantized Hall resistance standard in the AC regime were performed with both INRIM’s and PTB’s bridges. The result of the comparison and the last progresses of the GIQS project are here presented

PTB-INRIM comparison of novel digital impedance bridges with graphene impedance quantum standards

This paper describes an onsite comparison of two different digital impedance bridges when performing measurements on a quantum Hall resistance standard with the purpose of realizing the SI unit of capacitance, the farad. In the EMPIR Joint Research Project 18SIB07 GIQS, graphene impedance quantum standards, the Physikalisch-Technische Bundesanstalt (PTB), Germany, developed a Josephson impedance bridge, and the Istituto Nazionale di Ricerca Metrologica (INRIM) and the Politecnico di Torino (POLITO), Italy, developed an electronic digital impedance bridge. The former is based on Josephson waveform generators and the latter on an electronic waveform synthesizer. The INRIM–POLITO impedance bridge was moved to PTB and the two bridges were compared by measuring both temperature-controlled standards and a graphene AC quantized Hall resistance (QHR) standard. The uncertainties for the calibration of 10 nF capacitance standards at 1233 Hz are within 1 × 10−8 for the PTB's bridge and around 1 × 10−7 for the INRIM–POLITO's bridge. The comparison mutually validates the two bridges within the combined uncertainty. The result confirms that digital impedance bridges allow the realization of the SI farad from the QHR with uncertainties comparable with the best calibration capabilities of the BIPM and the major National Metrology Institutes

APMP.EM-S12 Comparison of Standards for the Calibration of Voltage, Current and Resistance Meters

The 14 Meeting of the APMP Technical Committee on Electricity and Magnetism, held on 5 December 2011 in Kobe, Japan, decided to hold a comparison of standards for the calibration of voltage, current and resistance meters at the lowest attainable level of uncertainty. This comparison complements the APMP.EM-S8 comparison using a 6.5 digit multimeter and the following comparisons of primary standards that provide traceability for the calibration of voltage, current and resistance meters: APMP.EM-K2: DC high resistance at 10 MΩ, 1 GΩ(in progress); APMP.EM.BIPM-K11.3: DC voltage, 10 V and 1.018 V (completed); APMP.EM-K6.a: AC/DC transfer at 3 V (completed); APMP.EM-K9: AC/DC transfer at 500 V, 1000 V (completed). The National Measurement Institute, Australia (NMIA) has been appointed as the pilot laboratory

The EMPIR Project GIQS:Graphene Impedance Quantum Standard

GIQS: Graphene Impedance Quantum Standard is a Joint Research Project of the European Metrology Programme for Innovation and Research (EMPIR). The project objective is to combine novel digital impedance measurement bridges with graphene-based ac quantum Hall resistance standards in a simplified cryogenic environment, to achieve simple, user-friendly quantum impedance standards suitable for primary realisation of impedance units in national metrology institutes, calibration centers, and the industry