Control enhanced estimation of the driving strength in a superconducting circuit

In this paper, we consider the system where a superconducting qubit is coupled to a resonator acting as a harmonic oscillator. Unlike the existing work regarding estimation of the coupling strength or oscillator frequency, we aim to sense the amplitude of a microwave drive by utilizing the qubit as a quantum probe. Furthermore, in order to improve the estimation precision, we employ a periodic control protocol that is easy to be implemented in practice. Such improvement does not require any manipulation of the oscillator. The proposed strategy sheds light on a systematic study on estimation of the driving field in superconducting circuits by means of adding control.