  Quantum metrology is supposed to significantly improve the precision of
parameter estimation by utilizing suitable quantum resources. However, the
predicted precision can be severely distorted by realistic noises. Here, we
propose a control-enhanced quantum metrology scheme to defend against these
noises for improving the metrology performance. Our scheme can automatically
alter the parameter encoding dynamics with adjustable controls, thus leading to
optimal resultant states that are less sensitive to the noises under
consideration. As a demonstration, we numerically apply it to the problem of
frequency estimation under several typical Markovian noise channels. Through
comparing our control-enhanced scheme with the standard scheme and the
ancilla-assisted scheme, we show that our scheme performs better and can
improve the estimation precision up to around one order of magnitude.
Furthermore, we conduct a proof-of-principle experiment in nuclear magnetic
resonance system to verify the effectiveness of the proposed scheme. The
research here is helpful for current quantum platforms to harness the power of
quantum metrology in realistic noise environments.
