This environmentally friendly quantum sensor runs on sunlight

[Uncle Joe]

[A new take on highly sensitive magnetic field sensors ditches the power-hungry lasers that previous devices have relied on to make their measurements and replaces them with sunlight. Lasers can gobble 100 watts or so of power — like keeping a bright lightbulb burning. The innovation potentially untethers quantum sensors from that energy need. The result is an environmentally friendly prototype on the forefront of technology, researchers report in an upcoming issue of Physical Review X Energy.

The big twist is in how the device uses sunlight. It doesn’t use solar cells to convert light into electricity. Instead, the sunlight does the job of the laser’s light, says Jiangfeng Du, a physicist at the University of Science and Technology of China in Hefei.

Quantum magnetometers often include a powerful green laser to measure magnetic fields. The laser shines on a diamond that contains atomic defects (SN: 2/26/08). The defects result when nitrogen atoms replace some of the carbon atoms that pure diamonds are made of. The green laser causes the nitrogen defects to fluoresce, emitting red light with an intensity that depends on the strength of the surrounding magnetic fields.

The new quantum sensor needs green light too. There’s plenty of that in sunlight, as seen in the green wavelengths reflected from tree leaves and grass. To collect enough of it to run their magnetometer, Du and colleagues replaced the laser with a lens 15 centimeters across to gather sunlight. They then filtered the light to remove all colors but green and focused it on a diamond with nitrogen atom defects. The result is red fluorescence that reveals magnetic field strengths just as laser-equipped magnetometers do.

(snip)

https://www.sciencenews.org/article/quantum-sensor-sunlight-environment-magnetic-field