The paper deals with recent progresses at INRiM towards the development and characterization of a programmable Josephson voltage standard (PJVS) operating in a small liquid helium dewar as well as with its integration for the realization of a practical quantum sampling electrical power standard. The PJVS is based on a 1 V superconductor-normal metal-superconductor (SNS) binary-divided array of 8192 Josephson junctions. To ensure proper operating conditions of the PJVS chip, a custom short cryoprobe was designed, built and successfully tested. The overall system is being developed in the framework of EMPIR project 19RPT01-QuantumPower. The goal is to establish a new quantum power standard (QPS) based on a single Josephson voltage standard for sampled power measurements and to gain confidence in running PJVS for precise calibration of digital sampling multimeters and arbitrary waveform digitizers used in the ac-voltage and power metrology community.
The paper deals with recent progresses at INRiM towards the development and characterization of a programmable Josephson voltage standard (PJVS) operating in a small liquid helium dewar as well as with its integration for the realization of a practical quantum sampling electrical power standard. The PJVS is based on a 1 V superconductor-normal metal-superconductor (SNS) binary-divided array of 8192 Josephson junctions. To ensure proper operating conditions of the PJVS chip, a custom short cryoprobe was designed, built and successfully tested. The overall system is being developed in the framework of EMPIR project 19RPT01-QuantumPower. The goal is to establish a new quantum power standard (QPS) based on a single Josephson voltage standard for sampled power measurements and to gain confidence in running PJVS for precise calibration of digital sampling multimeters and arbitrary waveform digitizers used in the ac-voltage and power metrology community.
The paper deals with recent progress at INRiM towards the setting up and preliminary characterization of a novel programmable Josephson voltage standard (PJVS) operating in a small liquid helium dewar.The PJVS setup is based on a 1-V superconductor-normal metal-superconductor (SNS) binary-divided array of 8192 Josephson junctions.To ensure proper operating conditions of the PJVS chip a custom short cryoprobe was designed, built and successfully tested.The overall system is being developed in the framework of EMPIR project 19RPT01-QuantumPower.The goal is to establish a new quantum voltage standard for sampled power measurement and to gain confidence in running quantum voltage standards for precise calibration of digital sampling multimeters and arbitrary waveform digitizers used in the ac-voltage and power metrology community.
The past few decades have witnessed great progress being made from the first voltage standards based on arrays of Josephson junctions. Continuous improvements in the fabrication process have increased the quality and “user-friendliness” of these superconducting circuits. Combined with the improvements in measuring electronics, the range of applications of Josephson-based measurements with unmatched precision has extended from DC into AC voltage metrology for signal frequencies up to 500 kHz. In this poster we will present several Josephson-based measurement systems developed for metrology applications. Two versions of quantum AC standards will be used as Josephson references: Programmable Josephson Voltage Standards (PJVS), which are based on serial arrays with up to 300,000 Josephson junctions, and pulse-driven arrays with more than 50,000 junctions, typically referred to as Josephson Arbitrary Waveform Synthesizers (JAWS). PJVS can reach amplitudes of up to 80 V, while pulse-driven arrays can reach up to 1 V or even 4 V. The advantage of pulse-driven Josephson voltage standards is that they are ideally suited as quantum-based voltage synthesizers for arbitrary waveforms or sine waves with high spectral purity. Therefore, they can be used directly to characterize or calibrate ADCs. In addition, JAWS are particularly useful in Josephson impedance bridges, which perform automated impedance calibrations at the 10-9 uncertainty level over a wide frequency range from 50 Hz to 80 kHz in a single bridge. We will further show how PJVS are used in commercial quantum voltmeters for DC and AC voltages and are typically used as quantum voltage references in measurement systems. Using differential sampling based on PJVS, uncertainties at the level of a few parts in 108 for frequencies up to the kHz range can be achieved. Such quantum-based AC voltage calibrations are at least 30 times faster than conventional AC-DC transfer and offer even better uncertainties. This idea has been quickly adopted by many National Metrology Institutes to establish such systems for AC voltage calibrations. As an example, the BIPM will now start worldwide onsite comparisons to ensure the uniformity of the new method which we introduced in 2006. But developments continue. Recently, a sub-sampling technique was used to extend the frequency range of the AC quantum voltmeter to up to 100 kHz with uncertainties below 5 parts in 106. In addition, a novel method, also for differential sampling, enables the measurement of arbitrary waveforms and the calibration of specific tones. Our poster will provide an overview of these Josephson-based metrological applications and present the latest developments from this fast-developing area.
The advancement of quantum metrology is intrinsically linked to the development of nanoelectronic and quantum devices. The Programmable Josephson Voltage Standard (PJVS), a system comprising thousands of superconducting Josephson junctions with tunnel barriers on the nanoscale, provides a fundamental quantum-based AC voltage reference. However, extending this quantum traceability to harmonic power measurements, essential for modern power systems with extensive power electronics, remains a significant challenge. This work demonstrates a high-accuracy harmonic power standard by leveraging the unique quantum properties of a nano-fabricated PJVS array. We introduce a time-division calibration scheme where the precise voltage steps of the PJVS are used to calibrate a high-performance dual-channel analog-to-digital converter (ADC). This method bypasses the need for complex synchronous sampling and heavy computational algorithms, relying instead on the intrinsic accuracy of the Josephson quantum voltage. The system achieves a measurement uncertainty of 14 × 10 ×6 ( k = 2) for fundamental power and 50 × 10 −6 ( k = 2) for harmonic power up to the 60th order. Comparative tests with national primary standards show a maximum deviation of only 6 × 10 −6 for harmonic power metrology but also serves as a compelling demonstration of a practical, high-precision application for superconducting nanoelectronic devices, bridging the gap between quantum standards and industrial measurement needs.
Abstract The paper describes a dry-cooled AC quantum voltmeter system operated up to kilohertz frequencies and 7 V rms. A 10 V programmable Josephson voltage standard (PJVS) array was installed on a pulse tube cooler (PTC) driven with a 4 kW air-cooled compressor. The operating margins at 70 GHz frequencies were investigated in detail and found to exceed 1 mA Shapiro step width. A key factor for the successful chip operation was the low on-chip power consumption of 65 mW in total. A thermal interface between PJVS chip and PTC cold stage was used to avoid a significant chip overheating. By installing the cryocooled PJVS array into an AC quantum voltmeter setup, several calibration measurements of dc standards and calibrator ac voltages up to 2 kHz frequencies were carried out to demonstrate the full functionality. The results are discussed and compared to systems with standard liquid helium cooling. For dc voltages, a direct comparison measurement between the dry-cooled AC quantum voltmeter and a liquid-helium based 10 V PJVS shows an agreement better than 1 part in 10 10 .
The programmable quantum voltage standard (PJVS) is a type of quantum voltage standard capable of generating AC waveforms accurately. This paper systematically summarizes the research progress of PJVS. The basic principles of PJVS are elaborated, focusing on the sources of transient errors and methods for error suppression. The development history of PJVS chips is reviewed, the fabrication of low-temperature superconducting Josephson junction arrays, the core characteristics of PJVS chips, and the research progress of PJVS chips at home and abroad are briefly summarized. The main application of PJVS are sorted out and summarized, the setup, key indicators, and practical application scenarios of quantum voltmeters, impedance bridges, and quantum current measurements are specifically analyzed. This paper also deeply explores the differential sampling method of PJVS and comparatively analyzes the two technical routes of differential sampling and subsampling. It conducts a comparative study on the two-terminal and four-terminal impedance bridges based on PJVS and summarizes their application status in various countries. It analyzes the advantages and disadvantages of current standards based on PJVS and single-electron tunneling schemes, and introduces the programmable quantum current standard based on Ohm’s law. Finally, this paper prospects the future development trend of PJVS from two dimensions of the breakthrough of core underlying chip technologies and the optimization of system integration.
The design, fabrication, and the characterization of a 0.5-V Josephson junction array device are presented for the quantum voltage standards in the National Institute of Metrology (NIM) of China. The device consists of four junction arrays, each of which has 1200 3-stacked Nb/Nb x Si1−x /Nb junctions and an on-chip superconducting microwave circuit which is mainly a power divider enabling each Josephson array being loaded with an equal amount of microwave power. A direct current (dc) quantum voltage of about 0.5 V with a ∼1-mA current margin of the 1st quantum voltage step is obtained. To further prove the quality of NIM device, a comparison between the NIM device with the National Institute of Standards and Technology (NIST) programmable Josephson voltage standard (PJVS) system device is conducted. The difference of the reproduced 0.5-V quantum voltage between the two devices is about 0.55 nV, which indicates good agreement between the two devices. With the homemade device, we have realized a precise and applicable 0.5-V applicable-level quantum voltage.