On May 19th, Physics Review Letters published the latest result of the team led by Prof. Cai Jianming in the School of Physics about the diamond-based quantum sensing and quantum metrology. The paper is entitled Scheme for Detection of Single-molecule Radical Pair Reaction Using Spin in Diamond. Prof. Cai is the corresponding author of this paper and the postdoc researcher Liu Haibin is the first author. Prof. Martin B. Plenio in the University of Ulm in Germany, who is an adjunct professor at the School of Physics of HUST also participated in this work.

In recent years, quantum metrology based on fundamental principles of quantum mechanics with potential applications e.g. in sensing and imaging on the micro (nano) scale has attracted increasingly interest. One of the most appealing quantum sensing technologies is based on quantum spin in diamond. Due to the excellent properties of quantum spin in diamond, the technology has been successfully applied to micro (nano)-scale precise detection of magnetic field, electric field, single spin, temperature and so on. Furthermore, because of the chemical inertness and biocompatibility, diamond spin sensor may have wide applications in biology and medicine.

Radical pair reaction also plays an important role in spin chemistry biology. The general detection methods usually apply to macroscopic samples (namely consisting of billions of molecules). Such ensemble measurement only allows to measure the average properties of macroscopic samples, while the unique information of single-molecule reaction may not be captured. Prof. Cai’s team proposed a new method using spin in diamond as a probe to detect the charge recombination of radical pair at a single-molecule level under ambient conditions. The result shows that the probe is sensitive enough to identity the influence of the direction of geomagnetic field on the single-molecule radical pair reaction.

The result is expected to provide a new route towards highly efficient detection of free radicals and the related kinetic processes at single-molecule level in physiological processes, including photosynthesis, biological magnetic sensing and radical involved organism diseases. Moreover, it may also boost the research on chemical synthesis or polymerization that involves electron transfer. The quantum physics and technology laboratory led by Prof. Cai is currently making intensive efforts to implement the detection technology in experiment.