%A Dong Xie(谢东), Chunling Xu(徐春玲) %T Quantum estimation of detection efficiency with no-knowledge quantum feedback %0 Journal Article %D 2018 %J Chin. Phys. B %R 10.1088/1674-1056/27/6/060303 %P 60303-060303 %V 27 %N 6 %U {https://cpb.iphy.ac.cn/CN/abstract/article_120690.shtml} %8 2018-06-05 %X We investigate that no-knowledge measurement-based feedback control is utilized to obtain the estimation precision of the detection efficiency. We show that no-knowledge measurement is the optimal way to estimate the detection efficiency. The higher precision can be achieved for the lower or larger detection efficiency. It is found that no-knowledge feedback can be used to cancel decoherence. No-knowledge feedback with a high detection efficiency can perform well in estimating frequency and detection efficiency parameters simultaneously; simultaneous estimation is better than independent estimation given by the same probes.