Two-photon microwave transitions and strong-field effects in a room-temperature Rydberg-atom gas

Thomas F. Gallagher

David Alexander Anderson, Andrew Schwarzkopf, Stephanie Miller +4 more

We investigate two-photon Autler-Townes splitting and strong-field effects of $^{85}\mathrm{Rb}$ Rydberg atoms in a room-temperature vapor cell. To observe the level structure we employ electromagnetically induced transparency. We first study the two-photon $62{S}_{1/2}\text{\ensuremath{-}}63{S}_{1/2}$ microwave transition using an electric-field reference measurement obtained with the one-photon $62{S}_{1/2}\text{\ensuremath{-}}62{P}_{3/2}$ transition. We then study the $61{D}_{5/2}\text{\ensuremath{-}}62{D}_{5/2}$ transition where the microwave electric-field range is extended up to $\ensuremath{\sim}40\phantom{\rule{0.28em}{0ex}}\mathrm{V}/\mathrm{m}$. A Floquet analysis is used to model field-induced level shifts and state-mixing effects present in the strongly driven quantum systems under consideration. Calculations are found to be in good agreement with experimental observations.

Matthias Moos, Razmik G. Unanyan, Michael Fleischhauer

Yongmei Xue, Yuechun Jiao, Liping Hao +1 more

We present a two-photon microwave spectra of cesium Rydberg atoms in the room-temperature vapor cell. The three-level atom including a ground state 6S1/2 (F = 4), an excited state 6P3/2 (F′ = 5) and Rydberg state consists of Rydberg electromagnetically induced transparency (Rydberg-EIT), that is employed to detect the microwave two-photon spectra. The microwave field with frequency ν DD = 11.42865 GHz couples the transition of Rydberg energy level |68D5/2〉 → |69D5/2〉, measured two-photon spectra display a rich of information including the microwave ac Stark shifts and two-photon Autler-Townes (AT) splitting. In the strong microwave field, the two-photon spectroscopy shows the state mixture between |68D5/2〉 and |68D3/2〉 Stark lines. The microwave two-photon spectra of the |69S1/2〉 → |70S1/2〉 transition coupled with frequency ν SS = 11.73503 GHz are also presented. The Floquet theory is employed to simulate the two-photon microwave spectra, showing the good agreement with the measurements. The work suggests the new method that may be used to investigate the multi-photon field-atom interaction and as an atom-based technique for precision field measurements.

Yijie Du, Nan Cong, Yao Liu +3 more

The power broadening of a coupling laser can be converted into two-photon detuning by electromagnetically induced transparency (EIT), resulting in a residual Doppler effect. The residual Doppler effect in a ladder-type EIT in a room-temperature atom ensemble is further amplified through a wavelength mismatch effect between the probe and coupling laser beams, which reduces the atomic coupling of light or microwaves. We measured the Rydberg spectra of the electric dipole (E1) and electric quadrupole (E2) microwave transitions, demonstrating that the reduction in the Rydberg EIT signal can be recovered through far-off-resonance E2 microwave transition dressing and achieving an 8-dB enhancement in the Rydberg EIT signal. The frequency-dependent dressing of the E2 transition enables the shift of the dressed Rydberg states to be tuned, thereby providing a scalable approach to optimize the interaction between the Rydberg state and microwave field.

Ravinder Rupchand Puri, Amitabh Joshi