Time and Frequency Resolution of Alternating Electric Signals via Single-Atom Sensor

Abstract

The characterization of externally applied signals is essential in order to improve performance and design appropriate engineering strategies in cold-atom experiments. Here, we present a practical technique to detect the artificially introduced electric signals by an exquisite sensor made of a single ${}^{40}$$\mathrm{Ca}$${}^{+}$ ion behaving as the phonon laser. The sensor can work as an oscilloscope, detecting spectra of the signals in the time domain, and also as a frequency spectrograph for the signal probe with respect to the frequency. The high precision of such an atomic sensor relies on the unique characteristics of the phonon laser. In particular, the sensor is practical since it works without the prerequisite of sideband cooling and the performance of the sensor can be further improved depending on better trapping conditions and a higher collection efficiency of the spontaneous emission fluorescence.