The new 10-volt system* builds on a number of previous NIST inventions, from the initial 1-volt standard in 1984 through the 2006 unveiling of the world's first precision instrument for directly measuring AC voltages.**
Because the measurements are made using integrated circuits based on quantum phenomena and simple equations that can be reproduced reliably, NIST quantum voltage standards represent a major advance over historical artifact standards, which were essentially chemical batteries that were influenced by environmental conditions and sometimes drifted over time.
About 50 standards labs, military organizations, and private companies worldwide calibrate voltmeters using standards based on earlier generations of NIST-developed technology. Products made with these instruments range from compact disc players to missile guidance systems.
The new technology relies on superconducting integrated circuits containing about 300,000 Josephson junctions, whose quantum behavior ensures that every junction produces exactly the same voltage. Quantum voltage standards are based on the Josephson effect, observed when two superconducting materials are separated by a thin insulating or resistive film and a current tunnels through the barrier (or junction). When microwave radiation of a known frequency is applied, the junction generates a voltage that can be calculated based on that frequency and two fundamental constants of nature.
The new standard offers unique advantages over previous generations. For DC metrology, benefits include higher immunity to noise (interference), output stability, and ease of system setup and operation. The system also enables a wider range of applications by producing AC waveforms for accurately calibrating AC signals with frequencies up to a few hundred hertz. A key advance is the use of junctions with metal-silicide barriers that produce stable steps and have uniform electrical properties. The system also incorporates new electronics, automation software, and measurement techniques.
The first system was shipped to the Kennedy Space Center in Florida earlier this month, and others are on order by standards laboratories in Brazil and Taiwan.
* C.J. Burroughs, P.D. Dresselhaus, A. RÜfenacht, D. Olaya, M.M. Elsbury, Y. Tang and S.P. Benz. "NIST 10 V programmable Josephson Voltage Standard System." Presented at the Conference on Precision Electromagnetic Measurements, Daejon, Korea, June 14, 2010.
** See NIST newsletter article "Road to AC Voltage Standard Leads to Important Junction" at www.nist.gov/pml/road_062006.cfm.
A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University
A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences