GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells

We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of $\sim 4\mathrm{ns}$. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.

Figure 1

Schema of the experiment. (a) The Rydberg state is addressed with a two-photon transition via an intermediate state. The laser for the upper transition is pulsed. (b) Transmission signal of the 780 nm laser (upper half) and corresponding laser intensities (lower half) as a function of time. (c) Simplified schematic of the optical setup.

Figure 2

Rabi oscillations for different pulse intensities. (a) Oscillations in the transmission of the 780 nm laser during the pulse. Both lasers are resonant to their respective transitions. The beginning of the pulse is at $t=0\mathrm{ns}$. (b) A corresponding simulation provides results for $\mathrm{Im}({\rho }_{21})$, which is connected to the absorption. The behavior of the experimental data is reproduced in excellent agreement. (c) Simulated Rydberg occupation ${\rho }_{33}$. Above the dashed line, the dynamics is dominated by the pulsed laser. All relevant parameters are described in the text.

Figure 3

Rabi oscillations for different detunings of the pulse. (a) Oscillations in the transmission of the 780 nm laser during the pulse. This laser is resonant to the $\mid 1⟩\to \mid 2⟩$ transition. The beginning of the pulse is at $t=0\mathrm{ns}$. (b) Simulation of $\mathrm{Im}({\rho }_{21})$ which is connected to the absorption. The behavior agrees very well with the experimental data. (c) Simulated behavior of $\mathrm{Im}({\rho }_{21})$ for the velocity class $v=0$ only. The black lines (both dashed and solid) indicate points of constant phase for the two oscillatory modes that occur.