A research team led by Prof Gang Chen from the School of Physics at Zhengzhou University (ZZU) has made significant progress in enhancing gravity sensing using levitated mesoscopic nanoparticles. This innovative study combines spin-entangled states with spatial superposition, achieving increased sensitivity in gravity measurements while enabling device miniaturization. The findings hold promise for applications in fundamental science, resource exploration, and inertial navigation.
Gravity measurement is crucial in fields like resource exploration, tidal measurement, polar motion, geodesy, and geophysics. Traditional methods have evolved from laser interference to matter-wave interference, achieving micro-gal sensitivity. However, existing atomic gravimeters are typically meter-sized, and miniaturization often compromises sensitivity. Addressing this challenge, the team proposed a gravity sensing scheme using ion-trapped levitated nanodiamonds, which enhances sensitivity while reducing the interferometer size.
Nanodiamonds with nitrogen-vacancy (N-V) centers offer significant mass and multiple spin centers, effectively reducing interference size and increasing signal strength. The protocol involves five steps: momentum splitting, free fall, momentum recombination, another free fall, and final momentum merging. This approach introduces gravitational acceleration into vibrational states, achieving a sensitivity of approximately 18 μGal/Hz^(-1/2) with a single N-V center nanodiamond over a 20-micron free fall. Using nanodiamonds with 100 N-V centers, the sensitivity surpasses the standard quantum limit, reaching over 0.4 μGal/Hz^(-1/2).
The study, titled "Enhanced Gravity Sensing by a Levitated Mesoscopic Nanoparticle", was published in Physical Review Letters. Luyun Wang, a PhD candidate at the School of Physics is the first author, with contributions from Kaifeng Cui, Leilei Yan, and Prof Gang. The work was supported by national research programs and foundations.