• The most advanced optical atomic clocks have achieved frequency stability and uncertainty at the 10^−19 level, making them crucial for redefining metrology methods. Large-scale quantum communication network can provide a new platform for precise dissemination of time and frequency. Especially, a global optical clock comparison network can be constructed through medium-high orbit quantum satellites carrying high-precision optical clocks. It is expected to open up the possibility of many exciting applications, including the next-generation definition of the unit of the ‘second’, the testing of general relativity, the search for gravitational waves and dark matter and so on.

  • Robotic space missions throughout the Solar System carry clocks/oscillator as part of their telecommunication systems. Some carry upgraded devices in the category of Ultra Stable Oscillators (USO) to utilize the same links as tools for scientific investigations. These Radio Science techniques enable the profiling of planetary atmospheric temperature and pressures, planetary rings, lunar gravitational fields, solar coronal density, and many other geophysical phenomena. Numerous scientific discoveries are attributed to these stable clocks.  This presentation will discuss the history and develop of USOs in deep space and their scientific applications, along with future techniques in the research phase.

  • Three experiments have recently achieved resonant laser excitation of a low-energy nuclear transition in the isotope Thorium-229, using table-top laser systems at 148 nm in the vacuum-ultraviolet. The thorium nuclei have been prepared as dopant ions in VUV-transparent crystals. This opens a new field for experiments that connect nuclear physics with atomic physics and quantum optics. Among several possible applications, the development of an optical nuclear clock seems particularly attractive. This clock would offer high accuracy, especially with laser cooled trapped Th-229 ions, high stability,  because of the high number of nuclei that can be interrogated in Th-229-doped solids, and high sensitivity in clock-based tests of fundamental principles of physics, involving the strong interaction in addition to electromagnetism.