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

Researchers have used quantum sensors to explore new interactions of particles at small-scale distances, presenting groundbreaking findings that extend the scope of the Standard Model in physics.

A research team led by Academician Du Jiangfeng and Professor Rong Xing from the University of Science and Technology of China (USTC), part of the Chinese Academy of Sciences (CAS), in collaboration with Professor Jiao Man from Zhejiang University, has used quantum state sensors of spin to examine exotic spin-spin-velocity-dependent (SSIVD) interactions in the short force range. Their study reports new experimental findings about interactions between electron spins and is published in Physical review papers.

The Standard Model is a very successful theoretical framework in particle physics, describing the fundamental particles and the four basic interactions. However, the Standard Model still cannot explain some important observational facts in current cosmology, such as dark matter and dark energy.

Some theories suggest that the new particles may act as propagators, transmitting new interactions between Standard Model particles. Currently, there is a dearth of experimental research on novel velocity-related interactions between spins, especially in the relatively small force-distance range, where experimental verification is almost non-existent.

Experimental Setup and Methodology

The researchers designed an experimental structure equipped with two diamonds. A high-quality nitrogen vacancy (NV) ensemble was prepared on the surface of each diamond using chemical vapor deposition. The electron spin in one NV ensemble serves as a spin sensor, while the other acts as a spin source.

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

For two new interactions, the researchers performed the first experimental detection in the force range of less than 1 cm and less than 1 km respectively, obtaining valid experimental data.

As the editor noted, “the results bring new insights to the quantum sensing community to explore fundamental interactions by exploiting the compact, flexible, and sensitive features of solid-state spins.”

Reference: “New constraints on exotic spin-spin-velocity-dependent interactions with solid-state quantum sensors” by Yue Huang, Hang Liang, Man Jiao, Pei Yu, Xiangyu Ye, Yijin Xie, Yi-Fu Cai, Chang -Kui Duan, Ya Wang, Xing Rong and Jiangfeng Du, 30 April 2024, Physical review papers.
DOI: 10.1103/PhysRevLett.132.180801