Towards a two-photon E1-M1 clock transition excitation in ^{174}Yb for quantum clock interferometry

Kurzfassung

Atom interferometry experiments measuring gravitational redshift require access to long-lived internal states, such as the 1S0-3P0 optical transition in group II atoms. An E1-M1 two-photon excitation directly access the clock state from the ground state by coupling to a far detuned intermediate state through a pair of electric and magnetic dipole allowed transitions [1]. This avoids state mixing, enhancing the excited state’s lifetime. Moreover, using counter-propagating photons with degenerate frequencies eliminates first-order Doppler effects. We report the progress of our experimental setup to drive the clock transition. We prepare an ultra-cold atomic ensemble of 174Yb through a dual-stage magneto-optical trap sequence, followed by evaporative cooling in a crossed optical dipole trap [2]. To excite the transition, we utilize a high power (10 W), narrow-linewidth l1156 nm laser system referenced to a high-finesse cavity and a frequency comb. We discuss further applications of the two-photon Doppler-free excitation as a beam splliting method for quantum clock interferometry experiments. [1]PRA 90, 012523 (2014). [2]J.Phys.B 54, 035302 (2021)