Figure 1

(a) The Λ-type three-level system used for CPT, including a Zeeman splitting between the $m_s=+1$ and $-$1 states. (b) Rabi oscillations observed between the $m_s$ $=$ 0 and $\pm$1 states (with no Zeeman splitting between the $m_s=+1$ and $-$1 states). Bottom trace: The resonant laser is tuned to the $m_s=\pm 1$ to $A_2$ transition. Top trace: The resonant laser is tuned to the transition between the $m_s$ $=$ 0 state and the $E_y$ excited state. Solid lines are a numerical fit to a damped periodic oscillation. Inset: The pulse sequence used. (c) PLE spectra of the two $A_2$ transitions, showing a Zeeman splitting of approximately 500 MHz. Solid lines are a Lorentzian fit.Reuse & Permissions

Figure 2

(a) CPT spectral response with the Rabi frequency of the optical fields exceeding the hyperfine splitting. The solid line is a Lorentzian fit. (b) The energy-level diagram with the hyperfine states labeled by their nuclear spin projection $m_n$. (c) CPT spectral responses obtained with relatively weak optical fields and with a strong microwave π pulse populating all three hyperfine states with $m_s$ $=$ 1. The solid line shows a fit to three Lorentzians. (d) Pulse sequence used for the nuclear-spin-dependent CPT. (e) CPT spectral response obtained with relatively weak optical fields and with a week microwave π pulse populating the $m_n=-1$ (blue or dashed line), $m_n=0$ (black or solid line), or $m_n=+1$ (red or dotted line) state (with $m_s$ $=$ 1).Reuse & Permissions

Figure 3

CPT spectral responses (vertically offset) in the presence of a strong resonant or nearly resonant second microwave field. (a) Responses obtained with the microwave field resonant with the $m_n$ $=$ 0 hyperfine state and with three different microwave powers. The traces are labeled with the microwave Rabi frequency. (b) Responses obtained with different microwave frequencies and with a fixed microwave power. For the top trace, the microwave frequency is 9.9 MHz above the spin transition for the $m_n$ $=$ 0 state. For the succeeding traces, the frequency is shifted down in steps of 2 MHz. In both (a) and (b), solid lines show a fit to six Lorentzians, with the center frequencies determined theoretically based on the microwave power and frequency and with the widths and depths of the dips as adjustable parameters.Reuse & Permissions