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NIST-on-a-Chip: Quantum-Based Electrical Standards - Voltage

NIST Josephson voltage chip

A NIST Josephson voltage chip next to a penny.

NIST scientists are expanding the capabilities of existing chip-based dc and ac voltage standards to higher voltages and frequencies. These efforts, along with development of new associated technologies, will support advanced manufacturing, precision testing, electric power distribution, and other applications that demand the highest possible accuracy in reference sources.

These new capabilities are likely to be deployable in the near future. As they do, it will become increasingly straightforward for anyone to use these superconductive electronics to ensure that their electrical measurements are the same as any other electrical measurements in different places and times because they are all derived from the same physics and fundamental units.

Recently, the researchers devised new techniques for the Programmable Josephson Voltage Standard (PJVS) to reduce leakage currents in the measurement system. That innovation can reduce the uncertainty of comparing two quantum systems to less than 1 part in 1010, and will change the global uncertainty of dc voltage measurements by an order of magnitude because the quantum standards maintained at various national metrology institutes and primary standards laboratories may now have significantly lower uncertainty budgets.

In ac metrology, scientists are making progress toward increasing the bandwidth of another NIST invention, the Josephson Arbitrary Waveform Synthesizer (JAWS), the ac Josephson voltage standard, which will soon join the JPVS as a NIST-distributed Standard Reference Instrument.

At present, JAWS systems generate accurate voltage signals, typically sine waves, for calibrating voltage measurement electronics at frequencies below 100 kHz.  The spectral purity of these waveforms results from synthesis with fast, quantized voltage pulses.

NIST researchers are developing the circuit designs and fabrication processes to extend quantum-based ac voltage synthesis from the present audio regime into the 1 MHz to 7 GHz frequency range to produce quantum-accurate waveforms relevant to microwave metrology, radar, wireless communications, and other microwave applications.

In the fall of 2016 they also increased the JAWS voltage output from 1V to a record 2V by combining two 1 V chips in series. That accomplishment required development of broadband superconducting microwave circuits, custom pulse-drive electronics and amplifiers, fabrication process improvements, cryogenic chip packaging, and automation software development (quantum state optimization and user interface).

Soon, NIST will construct a transferable calibration source including a broadband semiconductor bitstream generator for evaluating common wireless communications instruments and systems such as microwave receivers, frequency converters, and test equipment. It will also develop standard test signals for design and characterization of wireless components.

This work will lead to the development of a new generation of NIST-qualified signal sources that will have wide-ranging impact on the microwave and wireless communities. There is great demand in industry for engineered waveforms and standardized test signals that will simplify system test and measurement. This will, in turn, reduce design cycles, increase efficiency, and provide measurement assurance for the U.S. microwave and wireless industries. The increased accuracy in state-of-the-art wireless testing will also benefit the health-care industry’s move toward wireless data transfer and homeland defense agencies’ need for accurate and robust data and voice transmissions.


Created August 9, 2017, Updated November 15, 2019