Academician Du Jiangfeng from the University of Science and Technology of China and the Chinese Academy of Sciences, Professor Rong Xing, in collaboration with Researcher Jiao Man from Zhejiang University, have utilized solid-state spin quantum sensors to provide the most stringent experimental constraints on two velocity-dependent novel spin interactions at small scales. This achievement was recently published in "Physical Review Letters."
The Standard Model is a highly successful theoretical framework in particle physics, describing fundamental particles and four fundamental interactions. However, the Standard Model still cannot explain some important observational facts in current astrophysics, such as dark matter and dark energy.
Therefore, theoretical physicists have proposed the existence of new particles beyond the Standard Model. These particles may be the key to understanding the universe at a deeper level. The theory suggests that new particles can act as mediators, conveying new interactions between Standard Model particles, such as inducing velocity-dependent spin-spin interactions.
Currently, there is a lack of experimental research internationally on velocity-dependent new interactions between spins, especially within a relatively small range of distances, with almost no experimental verification. This is because the challenge in small-scale experiments lies in the need to simultaneously achieve coherent control of spin quantum states, high-precision magnetic detection, and precise spatial modulation at the micrometer scale.
To address this challenge, the research team carefully designed an experimental setup with two diamond pieces. Each diamond surface was prepared with high-quality nitrogen-vacancy (NV) ensembles using chemical vapor deposition. The electron spin in one NV ensemble served as the spin sensor, while the other acted as the spin source. By coherently manipulating the spin quantum states and their relative velocities of the two diamond NV ensembles at the micrometer scale, the team searched for the effects of velocity-dependent new spin-spin interactions between electron spins. Initially, they characterized the magnetic dipole interaction between the spin sensor and the spin source as a reference, then modulated the spin source vibration, and performed lock-in detection and phase orthogonal analysis to measure the velocity-dependent spin-spin new interactions. For the two new interactions, the team achieved the first experimental detection internationally within a range of less than 1 centimeter and less than 1 kilometer, obtaining valuable experimental search data.
Reviewers highly praised the work, stating, "This experiment explores fundamental interactions using a compact, flexible, and sensitive solid-state spin system, bringing new insights to the field of quantum sensing."
For more information on the paper, visit: https://doi.org/10.1103/PhysRevLett.132.180801
