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The paper summarizes current efforts to develop a novel alternating (AC) sampling standard at the PTB in cooperation with ZERA- and EMH-GmbH in Germany. This instrument shall operate in the frequency range of 40 Hz to 5 kHz and serve as a transfer standard, allowing measurements with basic accuracies of some muV/V at 50 Hz to be made. It is intended to ensure improved traceability to the PTB primary...
Josephson series array voltage standard at 10 volt level has been recently established at National Physical Laboratory (NPL), India. This paper describes the measurement set up and the results that have been obtained in calibrating the secondary standard.
Synthesizing Josephson stepwise sine waves to produce an AC quantum standard is limited by errors in the waveform transitions between quantized voltages. Many parameters have an impact on the shape of the transients. In this paper, the effect from microwave power and the position of the ground connection on the array chip are discussed.
By employing an array of 620 high-Tc Josephson junctions, we have achieved a maximum quantum output voltage with approximate value of 0.1 V at a temperature of 79.2 K and a frequency of 77.465 GHz. We also demonstrate that steps on the current-voltage characteristic of an array of bicrystal junctions at voltages of 70 mV were flat over the current range of 150 muA with a relative uncertainty of 0...
A new dual-heater thermal voltage converter (DH- TVC) with improved low-frequency performance has been developed at the AIST. Frequency characteristic of the DH-TVC was evaluated using a dual-output programmable Josephson voltage standard(DO-PJVS), and was confirmed to have low-frequency flatness better than 10-6 down to 1 Hz.
We have performed an experiment to drive an over-damped Josephson junction array (JJA) with modulated current pulse trains, which are generated by a modulated optical comb (an ultra-short pulse laser). The intensities of optical pulse trains are modulated using a pulse pattern generator. We quantitatively verified that the output voltages of the JJA were consistent with the modulation signals.
Interlaboratory comparison of the SMU 10 V Josephson array voltage standard (JAVS) has been carried out with the CMI JAVS. The comparison method was indirect using Zener diode reference as the traveling standard. This paper presents besides the results of the comparison that the parameters of the SMU primary standard have been preserved after the exchange of the Josephson array chip in the system...
A binary Josephson system was used to characterize an 81/2-digit sampling voltmeter. This voltmeter is the heart of the primary standard for power at 50 Hz or 60 Hz at several National Metrology Institutes (NMIs). In this paper, we present first results on the calibration of the voltmeter under conditions that mimic its use in the power standard set-up. Furthermore, the dependence of the root-mean-square...
We report operation of a programmable Josephson voltage standard on a closed-cycle refrigerator. NIST IV PJVS chip is used, and we operate the chip with the fingerboard that is adopted from the existing liquid helium dipping probe. We demonstrate operation at 5.5 K of chip temperature, with a flat Shapiro step in the sub-array of the chip.
AC voltages and arbitrary waveforms are synthesized by Josephson junctions operated by short current pulses. Series arrays of intrinsically shunted SNS Josephson junctions were developed and investigated for applications in this Josephson Arbitrary Waveform Synthesizer (JAWS). Amplitudes above 200 mV were generated by series arrays consisting of more than 10,000 junctions arranged in a meander-like...
High insulation low pass filters (LPFs) are often useful to improve the step stability of the Josephson array. However ordinarily available capacitors of high insulation at DC usually show a large transient leakage effect when the polarity of input voltage is reversed. A low leakage LPF with polarity reverse switch was made to reduce the transient leakage effect. The characteristics and its effect...
In this paper the setting up of a binary Josephson array waveform system for synthesization of arbitrary waveforms is described. The authors are with the Electricity Laboratory in the Metrology and Calibration Centre of INTA (Instituto Nacional de Tecnica Aeroespacial) in Torrejon de Ardoz, Madrid, Spain.
A two-way Josephson voltage standard (JVS) direct comparison between the National Institute of Standards and Technology (NIST) and the National Research Council (NRC) has been conducted. The process consists of two comparisons, one using NIST designed hardware and software and the other using NRC designed hardware and software. The results of the two comparisons are in agreement to within 0.7 nV and...
NIST recently reported the first application of a quantum AC Josephson voltage standard (ACJVS) for calibration of thermal transfer standards in the 1 kHz to 10 kHz frequency range. This paper describes preliminary work on extending its frequency calibration range up to 100 kHz by correcting systematic errors due to voltage leads.
We have been operating a 10-V programmable Josephson voltage standard (PJVS) system that was developed based on a multi-chip technique. We compared the PJVS with an SIS-based conventional JVS indirectly using a zener diode. The results agreed within 10-8 level.
The progress in developing Josephson voltage system contributes an increasing in the accuracy of the voltage unit transfer. Using the different methods during voltage standard key comparisons allows defining accuracy of compared standard with uncertainty, differing in 10-100 once. Some issues concerning measurement procedure to follow in voltage key comparison are discussed.
An ac-dc transfer measurement system based on a programmable Josephson voltage standard (PJVS) is being developed. Performance of the standard with dc and synthesized ac bias has been characterised. The first ac-dc transfer measurement results indicate agreement with conventional standards of the order of 1 muV/V at frequencies up to 40 Hz.
Nb/Al-AlOx/Nb Josephson junctions of few micrometers size, derived by the basic hysteretic SIS process, have shown stable overdamped current voltage, I-V, characteristic with Ic of 1-10 mA and Vc of 100-600 muV at 4.2 K. The moderate dependence on temperature of these parameters has allowed to use them at temperatures above 4.2 K, near the Nb transition temperature, measuring quantized voltage steps...
A new method to compare the Quantized Hall Resistance (QHR) with a conventional resistance standard is proposed. This new method uses a Binary junction programmable Josephson array specifically designed to have a center tap to simultaneously measure the voltage of the QHR and the test resistance. This new method is expected to compete in uncertainty with the Cryogenic Current Comparator at lower cost.
We describe a method for generating a low frequency sinusoidal calibration voltage with reference to a quantum standard, at the point of connection to the instrument under test (DUT). The voltage is made traceable to the maintained SI unit by a sampling system that compares the applied potential difference to that developed by an array of Josephson junctions. A feedback loop allows the use of a silicon...
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