  Real-time sensing of ultra-wideband radio-frequency signal with high
frequency resolution is challenging, which is confined by the sampling rate of
electronic analog-to-digital converter and the capability of digital signal
processing. By combining quantum mechanics with compressed sensing, quantum
compressed sensing is proposed for wideband radio-frequency signal frequency
measurement. By using an electro-optical crystal as a sensor which modulates
the wave function of the coherent photons with the signal to be measured. The
frequency spectrum could be recovered by detecting the modulated sparse photons
with a low time-jitter single-photon detector and a time-to-digital converter.
More than 50 GHz real-time analysis bandwidth is demonstrated with the Fourier
transform limit resolution. The further simulation shows it can be extended to
more than 300 GHz with the present technologies.
