According to a new study published in the journal Physical Review Applied, Australian researchers found that ordinary supermarket grapes can enhance quantum sensor performance by amplifying magnetic fields.
Traditionally, materials like sapphire have been used in quantum sensing devices. However, the researchers proposed that water, due to its properties, could perform better in concentrating microwave energy. "Water is actually better than sapphire at concentrating microwave energy, but it is also less stable and loses more energy in the process. That is the main challenge we need to solve," said Dr. Sarath Raman Nair, a lecturer in quantum technology at Macquarie University and co-author of the study, according to Phys.org.
The team utilized specialized nanodiamonds embedded with nitrogen-vacancy centers, which are tiny flaws that enhance quantum sensitivity. These centers behave like tiny magnets and can detect magnetic fields. By positioning their quantum sensors between two grapes, the researchers observed a doubling of the magnetic field strength. Interesting Engineering reports that the grapes serve as microwave resonators, effectively trapping and enhancing magnetic fields due to their high water content and morphology.
The phenomenon of grapes producing sparks in microwaves has long intrigued scientists and the public alike. Building on viral social media videos showing grapes creating plasma—glowing balls of electrically charged particles—in microwave ovens, the researchers explored how pairs of grapes generate strong localized magnetic field hotspots when microwaved. As reported by Phys.org, this effect opens doors for creating smaller and more efficient quantum sensors.
The brightness of the red glow emitted by the nanodiamonds indicates the intensity of the microwave field around the grapes. By passing green laser light through the fiber, the atoms in the diamond glow red, revealing the strength of the microwave field. This approach allows for precise measurement of magnetic fields, which is crucial for advancing quantum sensing applications.
The size and shape of the grapes were critical to the experiment's success. Experiments were conducted on grapes approximately 27 millimeters long to focus microwave energy at the correct frequency in diamond quantum sensors. "Grapes, which mainly have water in their thin skin, provided an ideal model to test the innovative approach of using water in quantum sensing," reported Interesting Engineering.
Professor Thomas Volz, the lead author of the research and head of the Quantum Materials and Applications Group at Macquarie University, expressed optimism about the findings. "This research opens up another avenue for exploring alternative microwave resonator designs for quantum technologies, potentially leading to more compact and efficient quantum sensing devices," he said, according to Phys.org.
Enhanced quantum sensors are essential components of quantum computers, atomic clocks, and ultra-precise measuring devices like gravitational wave detectors. Improved sensitivity and resolution in these sensors can also enhance imaging techniques like MRI. Advanced magnetic sensors can be employed in resource detection and Earth monitoring.
However, the study also found some challenges. The inherent instability of water presents difficulties for consistent application in sensors. The researchers noted concerns regarding the stability of water-based systems, which could pose challenges in practical applications. Nair acknowledged these concerns, stating, "That is the main challenge we need to solve," according to Phys.org.
Ongoing research aims to identify more stable materials that can leverage the properties of water, optimizing the performance of quantum sensors. The researchers are exploring more reliable materials to overcome the challenges of energy loss and instability associated with water. By hypothesizing that water could perform better than sapphire, they encourage a re-evaluation of material choices within the field.
The article was written with the assistance of a news analysis system.