Improvement Of Measurement Precision Of Linear Interferometer Based On Non-gaussian Operation

Quantum measurement plays an important role in the field of quantum information and quantum optics.In recent years,two kinds of non-Gaussian operations,photon subtraction and photon addition,have been proposed to improve the precision of phase estimation.This is because the non-Gaussian operation can be used to improve the nonclassicality of quantum states.For this reason,two new schemes to improve the phase measurement sensitivity are proposed based on two kinds of non-Gaussian operations(multiphoton catalytic(MC)operation and number-conserving generalized superposition of products(GSP)operation).Then,the conditions for improving the phase estimation precision are analyzed comprehensively by using the scheme of both quantum Fisher information and parity detection.The advantages and disadvantages of different non-Gaussian operations(including photon added and photon subtracted)for improving the phase measurement sensitivity are compared.The specific research contents of this thesis are summarized as follows:Firstly,we introduce the multiphoton catalysis two-mode squeezed vacuum(MCTMSV)state as an input of the Mach-Zehnder interferometer(MZI)and then study its phase sensitivity with photon-number parity measurement and the influence of photon losses.In addition,the statistical properties of MC-TMSV state are studied by the average photon number(APN),Wigner function and Mandel-Q parameter.The results show that MC-TMSV state can exhibit stronger nonclassical characteristics,thereby making the phase sensitivity more precise with either the increase of the photoncatalyzed number or the decrease of the transmissivity.In addition,considering the influence of photon loss involving external-and internal-loss processes of the MZI,it is found that the sensitivity of MC-TMSV state is significantly better than that with the TMSV state under the same parameters,especially in small initial squeezing regimes and serious photon losses,and multiphoton catalysis is more sensitive to external photon loss compared with the internal ones.Secondly,we introduce a theoretical scheme to improve the resolution and precision of phase measurement with parity detection by using a new nonclassical state generated by applying a number-conserving generalized superposition of products(GSP)operation,on TMSV state as the input of Mach-Zehnder interferometer.And the statistical properties of the proposed GSP-TMSV state are investigated through the APN,anti-bunching effect and two mode squeezing effect.It is found that both increasing the number m of GSP operations and decreasing the parameter s of GSP operations are beneficial to increase the total APN,which leads to the improvement of quantum Fisher information.In addition,we compare the phase measurement precisions with and without photon losses between our scheme and the previous photon subtraction or photon addition schemes.The results show that,compared with the photon add/subtract scheme,even in the presence of photon losses,GSP operation(especially when the photon is subtracted-then-added(s = 0))can improve the sensitivity of phase measurement more effectively.Interestingly,without losses,the standard quantum-noise limit(SQL)is always broken through for our scheme and the phase uncertainty associated with the state of our scheme is closer to the corresponding Heisenberg limit(HL)than that with the TMSV state in the larger total APN.However,in the presence of photon losses,the HL cannot be beaten,but the SQL can be broken through particularly for the large total APN regimes.