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Josephson Effect, Voltage

Working Group 2.63


Our working group works in the field of research, development, and optimization of new methods and instruments for traceable and highly precise measurements or synthesis of DC- and AC voltages based on the Josephson effect.  In recent years AC applications are gaining in importance as more and more national metrology institutes and a number of industrial laboratories have successfully installed conventional 10 V Josephson voltage  standards for routine calibrations.


Tasks of this working group are:

Voltage Standards  Maintenance of the electrical voltage based on the Josephson Effect


josephson arrays Development of new methods based on Josephson voltage standards


Quantum Metrological Measuring Facility Installation and improvement of new calibration facilities for quantum metrology

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Objectives of our  working group comprise research and development of


Cryoprobe with screen and Josephson chips  pulse-driven Josephson standards,


Schematic diagram of the quantum impedance bridge new methods, such as Josephson Impedance bridges,  and calibration techniques in the field of traceable dc and ac voltage with highest precision based on Josephson voltage standards,


A section of an array of Josephson Junctions  on the basis of Josephson arrays,  


Metrological Measuring Facility as well as Installation and improvement of new calibration facilities (AC quantum voltmeter) for quantum metrology, focusing on establishing these systems in industry.


This group works closely together with others of department 2 "Electricity" (PTB Braunschweig). Many projects are part of international research collaborations, e.g. European Metrology Research Program EMRP (Joint Research Projects "Q-WAVE" and "AIM QuTE") and the European Metrology Programme for Innovation and Research EMPIR (Joint Research Project "ACQ PRO").

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Our working group does not offer services. Group 2.1 Direct Current and Low Frequency is responsible for the dissemination of the electrical voltage by calibrating voltmeter (digital multimeter) and reference voltages.
Information about our calibration service can be found in our Database, or by contacting us directly.

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One task of this working group is the maintenance of the electrical voltage, Volt, based on the Josephson-Effect. Measurements based on this quantum effect allow for uncertainties of less than 1 nV for voltages up to 10 V.

Our world-leading measurement expertise with quantum voltage is confirmed by constant international intercomparisons with BIPM.




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