Figure 1

(a) Energy level diagram for the Rydberg EIT-AT system. A probe laser (\(\Omega _{p}\)) drives atoms from \(|1\rangle \) to \(|2\rangle \) and a coupling laser (\(\Omega _{c}\)) drives atoms from \(|2\rangle \) to \(|3\rangle \) transition. A local MW field (\(\Omega _{L}\)) resonantly couples the transition of \(|3\rangle \) to \(|4\rangle \), which causes the AT splitting of EIT spectrum, while the weak signal field (\(\Omega _{S}\)) has a detuning of \(\delta _{f}\). In the presence of the LO field, the Rydberg atoms work as an atomic mixer to down-convert the signal field to an intermediate frequency with a frequency of \(\delta _{f}\), which causes an oscillation in the transmission of the probe laser. (b) Sketch of the experimental setup for single channel Rydberg receiver. A coupling laser and a probe laser counter-propagate through a cylindrical room-temperature cesium cell. The transmission of the probe laser is detected by an avalanche photodiode (APD). Two RF fields, noted as the LO field and the signal field (\(E_{\mathrm{LO}}\) and \(E_{\mathrm{SIG}}\)), are applied transversely to the laser beams propagating through the vapor cell by two identical horn antennas. (c) Diagram of two-channel Rydberg receiver for increasing the response bandwidth. Both the probe and coupling lasers are split into two beams using a 50/50 beam splitter (BS) and counter-propagate through the cell. One channel is right above the other. The beam waists of each probe and coupling laser are set to \(\omega _{p}/\sqrt{2}\) and \(\omega _{c}/\sqrt{2}\). After propagating through the cell, two separated probe lasers pass through a dichroic mirror (DM) and are merged into a detector