  Radio reception relies on antennas for the collection of electromagnetic
fields carrying information, and receiver elements for demodulation and
retrieval of the transmitted information. Here we demonstrate an atom-based
receiver for AM and FM microwave communication with a 3-dB bandwidth in the
baseband of $\sim$100~kHz that provides optical circuit-free field pickup,
multi-band carrier capability, and inherently high field sensitivity. The
quantum receiver exploits field-sensitive cesium Rydberg vapors in a
centimeter-sized glass cell, and quantum-optical readout of baseband signals
modulated onto carriers with frequencies ranging over four octaves, from C-band
to Q-band. Receiver bandwidth, dynamic range and sideband suppression are
characterized, and acquisition of audio waveforms of human vocals demonstrated.
The atomic radio receiver is a valuable receiver technology because it does not
require antenna structures and is resilient against electromagnetic
interference, while affording multi-band operation in a single compact
receiving element.
