Researchers at NIST are advancing the **Quantum Metrology Triangle**, a standard that connects electric current, voltage, and resistance using quantum physics principles. This framework was solidified during the 2019 redefinition of the International System of Units (SI), which assigned exact values to fundamental constants like the Planck constant and elementary charge. The standard is now implemented, allowing scientists to verify electrical measurements by cross-checking any two units against the third to ensure consistency.
The system relies on two specific quantum effects: the Josephson effect for voltage and the Quantum Hall effect for resistance. By confirming that these measurements align with Ohm’s law at the quantum level, the standard ensures high-precision calibration for electrical instruments. This accuracy is critical for the development of quantum technologies, as future devices require exact control over electrical properties to function correctly.
While the constants were fixed in 2019, ongoing experiments continue to test the integrity of these relationships. This work supports long-term stability in electrical metrology, ensuring that the measurements used to build and operate quantum hardware remain reliable. The implementation timeline began with the 2019 update, with continued verification expected as the field evolves.
Source: https://www.nist.gov/si-redefinition/ampere/ampere-quantum-metrology-triangle
Keywords: Josephson effect, quantum Hall effect, SI redefinition
