Super-sensitivity measurement of tiny Doppler frequency shifts based on parametric amplification and squeezed vacuum state

Abstract

The precision measurement of Doppler frequency shifts is of great significance for improving the precision of speed measurement. This paper proposes a precision measurement scheme of tiny Doppler shifts by a parametric amplification process and squeezed vacuum state. This scheme takes a parametric amplification process and squeezed vacuum state into a detection system, so that the measurement precision of tiny Doppler shifts can exceed the Cramér–Rao bound of coherent light. Simultaneously, a simulation study is carried out on the theoretical basis, and the following results are obtained: for the signal light of Gaussian mode, when the amplification factor g = 1 and the squeezed factor r = 0.5, the measurement error of Doppler frequency shifts is 14.4% of the Cramér–Rao bound of the coherent light in our system. At the same time, when the local light mode and squeezed vacuum state mode are optimized, the measurement precision of this scheme can be further improved by ( 2 n + 1 ) / ( n + 1 ) times, where n is the mode-order of the signal light.