Beyond the Standard Model: New Spin-Spin-Velocity Experiments Could Rewrite Physics Textbooks

A groundbreaking study has been conducted by a team of Chinese researchers, led by Academician Du Jiangfeng and Professor Rong Xing from the University of Science and Technology of China (USTC), in collaboration with Professor Jiao Man from Zhejiang University. The team used solid-state spin quantum sensors to investigate new particle interactions at microscale distances, focusing on exotic spin-spin-velocity-dependent interactions (SSIVDs) at short force ranges. This study was published in Physical Review Letters.

The Standard Model, a successful theoretical framework in particle physics, describes fundamental particles and four basic interactions. However, it falls short in explaining certain observational facts in current cosmology, such as dark matter and dark energy. New particles are theorized to act as propagators, transmitting new interactions between Standard Model particles.

However, there has been a lack of experimental research on new interactions related to velocity between spins, especially in the relatively small range of force distance, where experimental verification is scarce. The researchers overcame this challenge by designing an experimental setup equipped with two diamonds. A high-quality nitrogen-vacancy (NV) ensemble was prepared on the surface of each diamond using chemical vapor deposition. One NV ensemble served as a spin sensor, while the other acted as a spin source.

By coherently manipulating the spin quantum states and relative velocities of the two diamond NV ensembles, the researchers were able to search for new interaction effects between the velocity-dependent spin of electrons on a micrometer scale. They first used a spin sensor to characterize the magnetic dipole interaction with the spin source as a reference. Then, by modulating the vibration of the spin source and performing lock-in detection and phase orthogonal analysis, they measured the SSIVDs.

The researchers conducted the first experimental detection for two new interactions in the force range of less than 1 cm and less than 1 km respectively, providing valuable experimental data. The results of the study are expected to bring new insights to the quantum sensing community, helping to explore fundamental interactions exploiting the compact, flexible, and sensitive features of solid-state spins.

The research was published in Physical Review Letters, with the title “New Constraints on Exotic Spin-Spin-Velocity-Dependent Interactions with Solid-State Quantum Sensors.” The article can be accessed with the DOI: 10.1103/PhysRevLett.132.180801.

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