July 9, 2025: In a major scientific advance, researchers at the Raman Research Institute (RRI) have developed a new magnetic sensing technology that uses the subtle quantum fluctuations known as spin noise to measure magnetic fields with high precision, without the need for bulky shielding or controlled lab environments.
This method, based on a technique called Raman-Driven Spin Noise Spectroscopy (RDSNS), could pave the way for compact, portable magnetometers capable of operating in real-world settings, from hospitals and factories to remote space missions.
Scientists at the Raman Research Institute (RRI), under India’s Department of Science and Technology (DST), have discovered this new way to measure invisible magnetic fields, from the human brain to deep space, using a compact, all-optical technology that works without the need for bulky magnetic shielding or specialized labs.
Magnetic fields are all around us. They play key roles in everything from brain activity to geological exploration and space science. Measuring these fields accurately, however, has always required highly controlled environments. Until now.
Researchers have created a new kind of magnetometer using a method called Raman-Driven Spin Noise Spectroscopy (RDSNS). This system listens to the tiny quantum movements, called “spin noise” of Rubidium atoms using laser light. These movements shift in response to magnetic fields, allowing precise measurements without touching or disturbing the atoms.
“This is a big step toward real-world, deployable magnetic sensors,” said Sayari, PhD researcher and lead author of the study. “Our setup is compact, highly sensitive, and works even in noisy environments where traditional systems fail.”
Unlike current high-end magnetometers, which trade off between sensitivity and range, RDSNS delivers both. It detects very weak and very strong magnetic fields with high precision, without the need for magnetic shielding. The system is fully optical, has no moving parts, and resists interference from electrical and mechanical noise.
The team’s prototype achieved a sensitivity of 30 picotesla per root hertz at 100 Hz, close to that of large lab-based machines, but in a compact form that could be made portable.
New Quantum Method Tracks Magnetic Fields Without Shielding or Interference
- In medicine, it could offer a quiet, portable alternative to MRI machines for scanning the brain and nervous system.
- In geology, it could help detect underground minerals by sensing subtle changes in the Earth’s magnetic field.
- In space exploration, where size and weight matter, the tech could measure magnetic environments around planets without requiring heavy shielding.
The findings were published in IEEE Transactions on Instrumentation and Measurement, as part of the National Quantum Mission of the DST.
Dr. Saptarishi Chaudhuri, who heads the Quantum Mixtures (QuMIX) lab at RRI, said, “We’re using atoms, the building blocks of quantum physics, to build smarter, lighter sensors that can work in the real world.”
Future versions of the device may include phase-locked lasers for even more stability and miniaturized chip-based designs using MEMS (Micro-Electro-Mechanical Systems) technology.
This breakthrough showcases how India’s growing quantum research ecosystem is producing technologies that could change how we explore the brain, Earth, and the universe.
