Quantum electronics for fundamental physics

Abstract

The emerging field of quantum sensors and electronics for fundamental physics is introduced, emphasising the role of thin-film superconducting devices. Although the next generation of ground-based and space-based experiments requires the development of advanced technology across the whole of the electromagnetic spectrum, this article focuses on ultra-low-noise techniques for radio to far-infrared wavelengths, where existing devices fall short of theoretical limits. Passive circuits, detectors and amplifiers are described from classical and quantum perspectives, and the sensitivities of detector-based and amplifier-based instruments discussed. Advances will be achieved through refinements in existing technology, but innovation is essential. The needed developments go beyond engineering and relate to theoretical studies that bring together concepts from quantum information theory, quantum field theory, classical circuit theory and device physics. This article has been written to introduce graduate-level scientists to quantum sensor physics, rather than as a formal review.

Keywords:

• Quantum technology for fundamental physics
• quantum electronics
• quantisation of circuits
• low-noise detectors
• mixers and amplifiers
• quantum noise limit
• superconducting devices
• submillimetre-wave and far-infrared imaging arrays

Acknowledgments

I am grateful to UKRI/STFC for the awards Quantum Technology for Measurement of Neutrino Mass (QTNM) ST/T006307/1, Quantum Sensors for the Hidden Sector (QSHS) ST/T006625/1 and Ultra-low-noise Superconducting Spectrometer Technology for Astrophysics ST/V000837/1. Over the years I have had numerous enlightening discussions with colleagues on superconducting device physics. In particular, I would like to thank Christopher Thomas, David Goldie, Songyuan Zhao, Michael Crane and Dorota Glowacka for their exceptional work on developing, fabricating and testing the many devices studied by the Quantum Sensors Group in Cambridge over a period of 20 years. I would also like to thank Dennis Molloy and David Sawford for their outstanding work on engineering and operating a long list of ultra-low-noise cryogenic systems.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Notes on contributors

S. Withington

S. Withington has worked on ultra-low-noise experiments for astronomy and fundamental physics for many years, including the development of ultra-low-noise instruments for submillimetre-wave and far-infrared space-based applications. His quantum sensors group at Cambridge has been developing and fabricating superconducting devices, microcircuits and imaging arrays for over 20 years. Stafford is now Emeritus Professor of Physics at the University of Cambridge, and Visiting Professor and Senior Researcher in the Department of Physics at the University of Oxford. He has held fellowships at Downing College Cambridge, All Souls College Oxford, Queens College Oxford and a Royal Society Fellowship at Chalmers University Sweden. He worked for various companies early in his career, including Ferranti Electronics Ltd., Marconi Space and Defence Systems Ltd. and Rolls Royce aircraft Engines (1971) Ltd.