Direct observation of two-photon-resonance Autler-Townes splitting of atomic sodium

Wankai Li, Yixuan Wang, Xing Li +3 more

A two-photon resonance in the sodium atom $3s\text{\ensuremath{-}}4s$ transition is investigated in the strong coupling regime with photoelectron momentum imaging techniques. The kinetic energies of the ionized electron map out the eigenenergies of the dressed states and emerge as the Autler-Townes (AT) splitting, which is proportional to the laser intensity due to the two-photon nature. The partial wave analysis of the angular distribution of the photoelectrons reveals the relative phase shift from dressed states which is related to the attosecond ionization time delays. The phase shift between the two electron wave packets produced from AT splitting are attributed to the combination of the Coulomb phase and the quantum defect phase.

P.-L. Zhang, S.-Y. Zhao

Peilin Zhang, Shuo-Yan Zhao

J. L. Picqué, Jacques Pinard

A two-step optical resonance experiment, which realizes the optical analogue of the Autler-Townes experiment, has been performed on a sodium atomic beam excited by two CW narrow-band dye lasers. An intense laser radiation was locked to a component of the D 2 resonance line while a weak laser radiation probed an upper connected transition. A dynamic Stark splitting of the probe transition was clearly observed for various intensities of the strong resonant radiation.

Zhihui Peng, J. H. Ding, Yu Zhou +7 more

We experimentally study a vacuum-induced Autler-Townes doublet in a superconducting three-level artificial atom strongly coupled to a coplanar waveguide resonator and simultaneously to a transmission line. The Autler-Townes splitting is observed in the reflection spectrum from the three-level atom in a transition between the ground state and the second excited state when the transition between the two excited states is resonant with a resonator. By applying a driving field to the resonator, we observe a change in the regime of the Autler-Townes splitting from quantum (vacuum-induced) to classical (with many resonator photons). Furthermore, we show that the reflection of propagating microwaves in a transmission line could be controlled by different frequency microwave fields at the single-photon level in a resonator.

P. F. Liao, John E. Bjorkholm, J. P. Gordon