Go further · Chapter 12 · 12b · A step deeper
How are quantum sensors used in the UK today?
The short answer (tap to open)
Two British quantum sensors have left the lab. A Birmingham gravity sensor found a hidden tunnel under a road in 2022 by sensing the missing mass. Wearable brain scanners from Nottingham use small quantum magnetometers on a helmet, so children can move during a scan. Neither is routine yet: the first NHS scanner sites are due from 2027.
How does a quantum gravity sensor work?
Last checked: 2 October 2026.
It drops a cloud of atoms cooled almost to a standstill (page 9b). Laser pulses split each atom into two paths, then bring the paths back together. Gravity pulls slightly differently on the two paths, and the interference at the end (chapter 4) reveals how strongly gravity pulled.
Earlier versions only worked in quiet labs, because every passing lorry shook the instrument. Birmingham's trick was a gradiometer: two atom clouds, one above the other. Vibration shakes both equally, so it cancels; a hidden hole changes gravity slightly differently at each height, so it shows.
Both traces, in words
- With one gravity sensor, the trace jumps up and down with every passing lorry, and the tiny change over the tunnel is lost.
- With the two-cloud gradiometer, the shake hits both clouds equally and cancels. The trace stays flat, then dips over the tunnel.
Less mass below means slightly less pull.
What has it found?
- 2022: the Birmingham sensor detected a 2 m tunnel about half a metre under a road (Nature), the first quantum gravity gradiometer used outside a lab.
- 2025: its spin-out, Delta.g, delivered its first next-generation sensor to the Department for Transport and raised £4.6 million.
The hope: map pipes, old mine workings and voids before digging, so fewer roads get opened in the wrong place.
How does a wearable brain scanner work?
Your brain's activity creates tiny magnetic fields, hundreds of millions of times weaker than the Earth's. The older method, MEG, reads them with sensors that need liquid-helium cooling inside a fixed helmet the size of a hairdryer hood. You must keep your head very still, which is hard for children.
The new sensors, optically pumped magnetometers, use a small glass cell of gas atoms warmed and read by laser light. They're about the size of a Lego brick and sit on a helmet right against the scalp, closer to the brain, so they pick up a stronger signal. A room lined with magnetic shielding blocks the Earth's field. Patients can nod, move and even play.
Where is it used?
- 2021: the UK's first MEG system dedicated to children opened at the charity Young Epilepsy, built with UCL and the University of Nottingham. Doctors aim to locate where seizures start, to guide surgery.
- 2026: the Nottingham spin-out Cerca Magnetics raised £3.8 million.
- From June 2027: a UK-funded project plans the first two NHS clinical sites, with clinical studies from 2028 and the aim of full regulatory approval.
- The UK's target: quantum brain scanners in precision surgery by 2028.
Check
Two quick ones
Collect
Your aha card
From lab bench to pavement and hospital.
UK quantum sensors now find tunnels and map brains, with routine use still ahead.