Quantum Sensing

New concept to me, but very much emerging.   This explains it.

Quantum Sensing Takes Shape   By Samuel Greengard

Commissioned by CACM Staff, April 27, 2021

" ...By measuring movements, rotations, absorption, and numerous other physical properties, quantum sensors can peer into previously invisible places...."

From compasses and thermometers to accelerometers and LiDAR, scientists and inventors have long searched for tools that help uBy measuring movements, rotations, absorption, and numerous other physical properties, quantum sensors can peer into previously invisible places.s understand our world better. Yet these devices typically run into the same basic limitation: they can only detect signals across a relatively narrow spectrum of light, sound, motion, and gravity waves.

That's poised to change. An emerging field called quantum sensing allows scientists to peer deeper into the surrounding world by detecting quantum state changes at an atomic and sub-atomic level. This technology would allow cars to see through fog, doctors to conduct medical scans with millimeter accuracy, and scientists to identify changes in the Earth that lead to seismic events such as earthquakes and volcanic eruptions.

The technology is nothing less than revolutionary. "Quantum sensors take detection far beyond what has ever been possible," says Kai Bongs, a professor in the School of Physics and Astronomy at the University of Birmingham in the U.K. "The field is likely to disrupt science and the economy in a major way."

Deep Sensing

The technology represents a quantum leap in sensing. Explained Jonathan L. Habif, a research assistant professor of electrical and computer engineering and research lead at the University of Southern California (USC), "For hundreds of years, we've modeled light and other properties as a wave based on their physical characteristics. But we're not able to calculate the fundamental structure and limits of nature simply by measuring light, sound or magnetic performance."

Yet characteristics such as light, sound, vibration, pressure, and magnetism are more than electromagnetic waves: "They're quantum mechanical systems," Habif says. This means some characteristics, qualities, and details lie beyond the scope of classical sensors. Yet by measuring movements, rotations, absorption, and numerous other physical properties, quantum sensors can peer into these previously invisible places.

Some quantum methods involve manipulating or "squeezing" photons to produce a higher signal-to-noise ratio, which enables ultrasensitive measurements. Others enhance or alter light-matter interactions. In the latter case, "This uniquely identifies the 'useful' signal from a classical background noise," says Daniele Faccio, Royal Academy of Engineering Chair in Emerging Technologies at the University of Glasgow School of Physics & Astronomy.

"Everything you can do classically, you can do quantum-mechanically," says Federico Spedalieri, a research assistant professor at USC, "but quantum mechanics may allow you to perform some sensing tasks better." In addition, he says quantum mechanics "introduces certain measurements that have no equivalent in classical systems." For example, it would allow a LiDAR system to see through fog, and perhaps around corners. It also makes it possible to develop sensing systems that find buried objects. ... "