Successful commercial demonstration of a cryogenic radio frequency power sensor paves the way for quantum computing

Radio frequency (RF) and microwave power measurements are widely used to support applications across space, security and communications. These precise measurements help engineers to accurately identify waveforms, components, circuits and systems.

Taking this a step further, NPL and Keysight Technologies collaborated on a research project, exploring RF power at cryogenic temperatures. This resulted in the world’s first successful demonstration of an RF voltage sensor operating at temperatures below 3 Kelvin.

“SI Traceable RF and Microwave Power Measurements at Cryogenic Temperatures” was presented at the 2024 Precision Electromagnetic Measurements (CPEM) Conference held in Denver, CO, US, and later published.

This not only marks a technological milestone, but an important step in supporting the development of quantum and other applications that require cryogenic conditions. Quantum technology has the potential to achieve massive breakthroughs, accelerating computing, communications and sensing.

However, another challenge is that quantum devices such as qubits require operation at cryogenic temperatures. These conditions, while necessary, present difficulties in maintaining signal integrity and producing accurate measurements.

The research focuses on using Keysight’s N8481S RF sensor, originally designed for room temperature operation, to make accurate measurements at cryogenic temperatures.

The thermopile response of the sensor was carefully measured at different RF power ranges from -35 dBm to 0 dBm at a frequency from 100 kHz to 10 GHz, to verify the SI performance with input power a well-known DC. This breakthrough opens up new opportunities in quantum technology, where precise measurements of RF power at cryogenic temperatures are essential.

Dr. Murat Celep, NPL senior scientist and scientific area leader, said, “NPL has more than 60 years of expertise in RF and microwave power metrology research. This experience, combined with state-of-the-art equipment top of cryogenic testing NPL and collaboration with Keysight, has enabled us to demonstrate cryogenic energy measurements of SI This is an exciting moment, and we look forward to seeing the quantum improvement continue.

“Our joint efforts have paved the way for the development of quantum computing and other applications that require the measurement of RF energy at cryogenic temperatures,” said Greg Patschke, general manager of Keysight’s Aerospace, Defense and Government Solutions Group. “This marks a significant milestone, and we are delighted to have partnered with NPL on this important research.”