A single quantum device can now define all three units critical for understanding electricity.

When calculating electricity, one must assess the current in amperes, resistance in ohms, and voltage in volts. Before proceeding, researchers need consensus on the measurements for each unit, which has historically required separate quantum devices and often necessitated visits to different labs.

Recently, Jason Underwood and his team at the National Institute of Standards and Technology (NIST) in Maryland have showcased how to characterize these units using a single device. “Integrating these two quantum standards has always felt like a Holy Grail,” he remarks. “It was a prolonged endeavor. Much like Sisyphus, we’ve been pushing this boulder uphill.”

This integration posed challenges as both devices depend on delicate quantum effects observable only at extremely low temperatures. Additionally, certain devices historically required magnetic fields, which could disrupt the operation of others.

The innovative “One Box” approach circumvents these issues by utilizing new materials capable of conducting quantum functions without the need for magnetic fields, allowing previously separated quantum systems to function together within the same cryostat. This method successfully measures amperes, ohms, and volts with an uncertainty of just one in millions for each unit.

However, before these combined devices can be used practically, researchers must further enhance their precision. Currently, accuracy is hampered by the heating generated when placing the two systems and their wiring too closely together. Moreover, development on the new quantum material, which facilitates the cooperation of both systems, is ongoing, according to Lindsey Rodenbach at Stanford University in California.

He views the project as a significant achievement, yet Underwood highlights that Budget constraints at NIST, funded by the US government, have impeded the team’s reach for even higher precision. He specifically mentions the agency’s “Crossing Infrastructure” report, which revealed that several NIST facilities are in disrepair. NIST has chosen not to comment on the matter.

Susmit Kumar from the Norwegian Metrology Service describes the new device as an “impressive engineering feat” that could enhance quantum electrical standards, making them more accessible and affordable for researchers and tech developers worldwide. He is part of the Quahmet Consortium, which also aims to develop user-friendly devices for measuring ohms using novel materials.

“The International System of Units is a shared language for scientists and engineers everywhere. Our goal is to simplify their use as much as possible,” says Richard Davis, a retired member of the International Bureau of Weights and Measures. He adds that integrating existing devices will foster advancement moving forward.