Instead of using power-hungry lasers, as was done with prior versions of these sensors, the new design measures the magnetic field using light from the sun. About the same amount of energy is required to keep a 100-watt light bulb on can be consumed by a laser. The development has the potential to free quantum sensors from this constraint. In the next issue of Physical Review X Energy, researchers will detail their findings, which include a prototype of cutting-edge technology that is also ecologically benign.
The device’s innovative usage of sunlight is the main selling point. In other words, it doesn’t make use of photovoltaic cells to generate power from sunlight. According to Jiangfeng Du, a physicist from China’s University of Science and Technology in Hefei, natural sunshine can replace laser light. In order to measure magnetic fields, many quantum magnetometers use a strong green laser. Radiation from the laser illuminates atomic flaws in a diamond (SN: 2/26/08). Nitrogen atoms replace some of the carbon atoms that make up pure diamonds, resulting in the flaws. By shining a green laser beam on them, nitrogen defects glow, giving off a red light whose brightness varies with the strength of the magnetic fields around them.
Additionally, green light is required by the novel quantum sensor. Sunlight contains a lot of it, as can be seen in the green light reflected off plants and grass. Du and his coworkers swapped out the laser for a lens 15 cm in diameter to catch enough sunlight to power their magnetometer. The light was then concentrated on a diamond with nitrogen atom flaws while being filtered to exclude all hues except green. The resulting red fluorescence can be used, like laser-equipped magnetometers, to measure magnetic field strengths.
The technique by which solar cells convert light into electricity is inefficient due to the nature of energy conversion (SN: 7/26/17). In comparison to using solar cells to power lasers, the researchers believe their method is three times more efficient. Physicist Yen-Hung Lin from the University of Oxford who was not involved in the work says, “I’ve never seen any other papers that tie solar research to quantum technology.” More cross-disciplinary energy studies may result.
Researchers believe that their solar-powered method might be applied to other quantum devices that detect subtle changes in conditions such as electric fields or pressure. In example, quantum sensors designed for use in space could benefit from the bright sunlight present outside Earth’s atmosphere. The remainder of the light, at wavelengths not used by the quantum sensors, might power electronics used to process the quantum signals. The solar-powered magnetometer is just the beginning of the integration of quantum and green technologies. In its current form, “this equipment is solely for developmental reasons,” Du notes. We anticipate the gadgets will be put to useful ends. Although there is much to be accomplished.