Research progress of terahertz quantum frequency standard

A highly stable clock is indispensable for electronic systems in navigation, communication, and sensing, with the frequency standard serving as its core component. However, meeting the demands of high-precision military operations and aerospace activities using a crystal oscillator remains significant challenges. The quantum frequency standard based on the specific transition frequencies of ground state atoms or molecules is superior to the conventional crystal oscillator. However, the current quantum frequency standard based on atomic clocks either fails to meet the requirements of battlefield scheduling and other scenarios due to its excessive size or is prohibitively expensive for universal implementation. With the advancement of terahertz spectroscopy and electronics technology, a terahertz molecular clock based on Carbonyl Sulfide (i.e., ¹⁶O¹²C³²S) as a reference molecule has emerged, offering a novel avenue for the further progression of terahertz quantum frequency standards. It can not only have several orders of magnitude higher stability and accuracy than the traditional crystal oscillator, but also greatly reduce the device size and production costs. With the technological breakthroughs in related fields, in the near future, the terahertz quantum frequency standard will provide key support for modern people’s production and life and scientific research and exploration, which has far-reaching and great significance.