Super-sensitive detection of quantum interferometer in atmospheric environment

Abstract

With squeezed states or entangled states being the source, quantum metrology, imaging and sensing can break the standard quantum limit (SQL), even reach the Heisenberg limit (HL), which is difficult to achieve by traditional methods. However, the photon loss or phase fluctuation caused by the atmospheric attenuation and turbulence cannot be ignored in the actual application. Atmospheric transmittance and phase fluctuation are related to the detection distance, and the phase sensitivity becomes worse as the distance increases. As the functions of distance, the photon loss and phase fluctuation are uniformly expressed according to the introduction of atmospheric attenuation coefficient, turbulence structure constant and receive aperture size in this paper. The density matrixes and phase sensitivities of N00N states and M&M′ states in the atmospheric environment are proposed in terms of distance variables. Then the quantitative computation of super-sensitive distance is carried out. SQL-contour is proposed to describe the super-sensitive ability of the quantum interferometer for the affection from both photon loss and phase fluctuation. The simulation results show that, in atmospheric environment the super-sensitive distance can reach hundreds of meters. M&M′ states with less total photon number are more likely to reflect the advantage of super-sensitivity. SQL-contour can provide references for interferometric source choosing.