Electromagnetically induced transparency and population repump readout of Rydberg states of Cs atoms in a J-scheme

Abstract

Rydberg atom electrometry offers traceable electric field measurements over many decades of radio frequencies in a single device. Miniaturization of these sensors is primarily limited by requirements of the lasers used. Here we demonstrate a three-photon sensing scheme using a J-shaped energy level coupling that can be achieved using external cavity diode lasers, without the need for a doubling crystal or tapered amplifier. In the low laser power regime, we demonstrate a full-width at half-maximum linewidth of 1.3 MHz. We demonstrate that for RF field electrometry using conventional heterodyne techniques, we can detect 4.7 GHz at a sensitivity of 27 μV m-1 Hz-1/2, comparable to that of two-photon detection schemes which require the use of a tapered amplifier. We also investigate a modified scheme where the probe laser is locked to a different hyperfine state, thus measuring the two-photon electromagnetically induced transparency in the other two lasers via the change in population of this separate state due to repumping. In this scheme we find the sensitivity for a 4.7 GHz field to be 39 μV m-1 Hz-1/2, and demonstrate that the amplitude scaling with probe power offers a different saturation profile than the linked J-scheme counterpart.

Figures (7)

• Figure 1: The "J"-shaped electromagnetically induced transparency scheme. a The energy level diagram of the measurement scheme. b The configuration of the lasers' $k$-vectors.
• Figure 2: Lineshape of the three-photon transparency on the $50D_{5/2}$ state in the low-power regime.
• Figure 3: Sensitivity measurement of the system on the 4.7 GHz $53D_{5/2} \rightarrow 54P_{3/2}$ transition. a The Autler-Townes splitting of the $53D_{5/2}$ state is measured at various powers (left), and the field inferred from the splitting is used to calibrate the field at the atoms as a function of the power applied to the horn (right). b With a local oscillator, an 11 kHz beatnote is formed, and the minimum detectable field (MDF) is determined for a resolution bandwidth of 10 Hz.
• Figure 4: Energy level diagram of the repump readout scheme.
• Figure 5: Two-photon (probe, dressing) resonance scan displaying both the EIT and repump features with the probe locked to the $F=4$ state (top) and the $F=3$ state (middle, bottom). On the bottom plot, the $F$ of the $6S_{1/2}$ state and the $F'$ of the $7P_{3/2}$ state are labeled for each spectral feature.