Rydberg excitation spectrum of 40K ultracold Fermi gases

We report the measurement of the Rydberg excitation spectrum by two-photon process in ultracold( 40)K Fermi gases. Two different methods are employed to measure the Rydberg excitation spectrum, depending on the power of the probe laser. One scheme is to reduce atomic losses by means of electromagnetically induced transparency. The other is to enhance the atomic losses by spontaneous avalanche ionization due to the strong Rydberg-Rydberg interactions. We verify the consistency of both of the methods. The highest Rydberg states detectable in our experiment are limited to n <= 62 due to the competition between the long Rydberg blockade effective range and the limited atomic cloud size.

Automated summary

The study reports the measurement of the Rydberg excitation spectrum in ultra-cold (40K) Fermi gases through a two-photon process. Two methods were employed, one to reduce atomic losses using electromagnetically induced transparency, and the other to enhance losses through spontaneous avalanche ionization due to strong Rydberg-Rydberg interactions. The highest detectable Rydberg states were limited to n <= 62 due to competition between the long Rydberg blockade effective range and limited atomic cloud size.