In a significant advance that could miniaturize MRI-like machines from massive room‑sized setups to portable units, researchers at the Raman Research Institute (RRI) have built a lightweight magnetometer capable of detecting magnetic fields with remarkable accuracy even in everyday, noisy environments.
This innovation paves the way for a quieter, cheaper, and portable alternative to traditional MRI scans something that could be invaluable for small clinics, mobile diagnostic vans, and rural healthcare facilities.
How MRIs work and the challenge they pose
MRI (Magnetic Resonance Imaging) systems work by picking up extremely faint magnetic signals from inside the body, particularly the brain. Because these signals are so weak, conventional machines require heavy magnetic shielding and ultra‑silent rooms to function.
The new RRI device does away with all of that. It is a compact, fully optical, shield‑free magnetometer that can sense magnetic fields in real‑world conditions in clinics, outdoors, or even in spacecraft without needing a controlled environment.
What sets this apart from existing magnetometers
Magnetometers, which measure magnetic fields, are widely used in navigation, earth sciences, medical imaging, physics, and space exploration. The most sensitive types such as Optically Pumped Atomic Magnetometers (OPAMs) and Spin‑Exchange Relaxation‑Free (SERF) magnetometers perform well only in shielded labs and struggle when exposed to stronger magnetic fields, limiting their dynamic range.
RRI scientists broke through this limitation by introducing a technique called Raman‑Driven Spin Noise Spectroscopy (RDSNS). Using lasers, they monitor the tiny, random spin fluctuations or “spin noise” of rubidium atoms. These atoms act like miniature bar magnets, and their spin noise subtly shifts when a magnetic field is present. By reading these shifts optically, the team can accurately measure magnetic fields without physical contact and without interference from electricity, vibrations, or radio signals.
A rare combination: high sensitivity and wide range
Typically, magnetometers must trade off between sensitivity (picking up very faint signals) and dynamic range (handling both weak and strong fields). Devices that excel in one area often perform poorly in the other.
The RRI team managed to achieve both in a single system. “We have combined high sensitivity with an unusually large dynamic range something that is extremely difficult to achieve,” said Sayari, a PhD researcher and lead author of the study.
The new device reaches a sensitivity of 30 picotesla per root hertz at 100 Hz, comparable to bulky, high-end lab equipment but in a compact, fully optical form that needs no shielding.
“Our approach reflects India’s growing ambition in the global quantum technology race,” said Dr. Saptarishi Chaudhuri, head of the Quantum Mixtures (QuMIX) Lab at RRI. “We are using atoms nature’s quantum building blocks to design next-generation sensors.”
Potential applications
- Healthcare: Portable, quiet brain-scanning devices that could replace expensive MRI machines, especially in low-resource settings.
- Geology: Mapping underground minerals by detecting subtle magnetic changes in the Earth’s crust.
- Space: Lightweight, shield-free sensors suitable for satellites and spacecraft to study planetary and stellar magnetic fields.
