Quantum device detects all units of electricity at once

A single quantum device could define the three units we use to understand electricity.

When you measure the electricity, you must find the flow of the flow in the amps, its resistance in the Ohms and its voltage in volts. But even before they start, researchers must agree on the size of each of these units. So far, this has required two distinct quantum devices, and often the expensive and complicated task of visiting two distinct laboratories.

Now, Jason Underwood at the National Institute of Standards and Technology (NIST) in Maryland and his colleagues showed how we could characterize these units using a single device. “The idea of integrating these two quantum standards has always been a kind of Saint Grail,” he says. “It’s been a long time since Sisyphe, we continued to push the rock on the hill.”

This integration was difficult because the two devices are based on fragile quantum phenomena which can only be observed at very low temperatures – so low that they must be used in special refrigerators called cryostats. Traditionally, a device also required a magnetic field that has disrupted the operation of the other.

The new “One box” method bypasses this problem using a new material that can perform its quantum tips without the magnetic field, so that two quantum systems that had to be separated can work in the same cryostat. The team used it to obtain amps, ohms and volts with uncertainties as small as a few million of each unit.

Before researchers can use the combined device in practice, however, its precision must be further increased. For the moment, it is limited by the way the two systems and their wiring warm up when placed side by side. In addition, work is underway to perfect the quantum material still “juvenile” which allows two systems to work together, explains Linsey Rodenbach at the University of Stanford in California.

Although he considers the project as an unreserved success, Underwood says that another thing that prevented the team from reaching even higher details were bad conditions at the NIST, which is funded by the United States government. He particularly noted the “ruined infrastructure of the institution”, as described in a study in 2023 which revealed that several buildings of the NIST deteriorated. Nist refused to comment.

Susmit Kumar in the Norwegian metrology service says that the new device is an “impressive engineering success” and could make quantum electrical standards more profitable and easier to access scientists and technology developers around the world. It is part of the Quahmet consortium, which also uses new materials to develop a device that is easier to use to determine the OHM.

“The international system of units is a common language that all scientists and engineers use. You want to make this as useful as possible, ”explains Richard Davis, who is withdrawn from the International Bureau of Weights and Measures. He says that efforts to unify different devices that are currently used can speed up in the future.