Fig. 1: Main components of the experiment.

a Schematic of the atomic frequency-division multiplexing scheme. The microwave cavity-vapor cell system acts analogously to an RF mixer, and information encoded in idler (yellow) channels (▲, ●, ■) is combined coherently with multiple pump (red) channels to produce many output signal (blue) channels over a range of optical frequencies. b A representation of our microwave cavity and the generation process. The optical pump beam passes transversely through the cavity and cell and is polarized along the z-axis, parallel to a weak magnetic field. The cavity’s TE₀₁₁ mode overlaps with the pump interaction region inside the vapor cell. The arrows define the beam propagation and polarization directions. c Three-level energy diagram showing the cyclical transition scheme. The idler (ω_I) and pump (ω_P) fields combine coherently in the vapor to produce the signal field (ω_S). The frequencies shown are for ⁸⁷Rb; in a room-temperature vapor, the excited state addressed by the pump field is Doppler-broadened by ~550 MHz.