State-of-the-art atomic clocks achieved fractional uncertainties below 10^-18. In these clocks, effects of conventional external fields, such as electric and magnetic fields, are suppressed for the high accuracy. Under this condition, the system can potentially be sensitive to tiny energy shifts caused by hypothetical fields weakly coupled to ordinary matter or by effects mediated by massive particles. Based on this idea, various searches for new particles and fields are performed using precision spectroscopy.
In this seminar, starting from the overview of precision spectroscopy of atoms and its applications to fundamental physics searches, I will describe some major recent progress in the field. Particularly, I focus on the topics related to the new clock transition at 431 nm in ytterbium that has high sensitivity to variation of the fine structure constant and fifth forces between a neutron and an electron.