As humanity's exploration of the Earth's internal structure deepens, Earth's free oscillations, serving as crucial "fingerprints" for revealing the large-scale structure and dynamic processes within the Earth, have always been a core subject in geophysics. Ground-based station observations are currently the mainstream method for measuring Earth's free oscillations. With the advancement of space technology, high-precision inter-satellite distance measurement holds the potential to become a novel method for detecting these oscillations.

In a recent paper published in Space: Science & Technology, a research team from the School of Physics and Astronomy at Sun Yat-sen University, in collaboration with the TianQin Research Center for Gravitational Physics, proposed a novel detection and analysis method for Earth's free oscillations utilizing the "TianQin" space-borne gravitational wave detector. The study constructed a theoretical response model for Earth's free oscillations within the TianQin detector and derived their analytical waveform for high-orbit satellite laser interferometric measurements. Through numerical simulation and Bayesian parameter estimation, the research team demonstrated that for a major seismic event like the 2008 Wenchuan earthquake, TianQin could achieve a clear detection with a signal-to-noise ratio as high as 73 and independently distinguish at least nine different free oscillation modes.

Harvard researchers built a racetrack-shaped quantum cascade laser that makes bright, stable, mid-infrared frequency combs on a chip.