A new approach to highly sensitive magnetic field sensors uses sunlight instead of power-hungry lasers, which is how previous devices made their measurements.
Lasers can consume roughly 100 watts of power, which is equivalent to maintaining a bright lightbulb. This innovation may liberate quantum sensors from this energy requirement. In a forthcoming issue of Physical Review X Energy, researchers will describe a prototype that is environmentally friendly and technologically advanced.
The most innovative aspect of this device is how it uses sunlight. It does not convert light into electricity using solar cells. According to Jiangfeng Du, a physicist at the University of Science and Technology of China in Hefei, sunlight replaces the laser’s light.
Is It really Environment-Friendly?
Quantum magnetometers frequently incorporate a potent green laser for measuring magnetic fields. The laser illuminates a diamond with atomic flaws (SN: 2/26/08). When nitrogen atoms replace some of the carbon atoms that make up pure diamonds, defects result. The green laser causes nitrogen defects to fluoresce, emitting red light with an intensity dependent on the strength of the magnetic fields in the vicinity.
The new quantum sensor also requires green light. It is abundant in sunlight, as evidenced by the green wavelengths reflected from tree leaves and grass. To gather sufficient sunlight to power their magnetometer, Du and his colleagues replaced the laser with a 15-centimeter-wide lens. They then removed all colors except green from the light and focused it on a diamond with nitrogen atom defects. As with laser-equipped magnetometers, the outcome is a red fluorescence that indicates magnetic field strengths.
Changing energy from one form to another is inherently inefficient (SN: 7-26-2012). Researchers claim that by avoiding the conversion of sunlight into electricity to power lasers, their method is three times more efficient than if lasers were powered by solar cells.
According to the researchers, quantum devices sensitive to other factors, such as electric fields or pressure, could also benefit from the solar-powered method. In particular, space-based quantum technology could utilize the intense sunlight available outside the Earth’s atmosphere to provide the light that is optimal for quantum sensors. The remaining light with wavelengths not utilized by quantum sensors could be used to power solar cells that process the quantum signals.
The solar-powered magnetometer is only the beginning of the fusion of quantum and environmentally sustainable technology.
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