In analogy to the classical double lock-in amplifier, this work presents a general protocol for achieving a quantum double lock-in amplifier to extract complete information about the signal’s amplitude, frequency, and initial phase. The realization of the quantum double lock-in amplifier is illustrated using a five-level double-Λ coherent population trapping system as an example.
- Sijie Chen
- Min Zhuang
- Chaohong Lee