Estimation of the Laser Frequency Noise Spectrum by Continuous Dynamical Decoupling

Decoherence induced by laser frequency noise is one of the most important obstacles in quantum information processing. In order to suppress this decoherence, power spectral density needs be accurately characterized. particular, spectrum measurement based on coherence characteristics qubits would a meaningful and still challenging method. Here, we theoretically analyze experimentally obtain continuous dynamical decoupling technique. We first estimate mixture-noise (including magnetic noises) up $(2\ensuremath{\pi})530$ kHz monitoring transverse relaxation from an initial state $+X$, followed gradient descent data process protocol. Then contribution extracted encoding different Zeeman sublevels. also investigate two sufficiently strong components making analogy between these noises driving lasers whose linewidth assumed negligible. This method verified finally helps characterize noise.