Research Of Application Of Quantum Enhanced Sensor Based On Interferometers

Manipulation and measurement of quantum states are foundations of quantum information and quantum calculation science.The rapid development of these quantum sciences in the past few decades and laser techniques improved the techniques of precise control of the microscopic systems,such as atomic systems and molecular systems.The precision measurement technology based on phonics,atoms and molecules has also been greatly boosted.Higher sensitivity and more precision are the fundamental goal of various quantum sciences.Consequently,the development of quantum measurement is an inevitable trend and gives birth to the quantum metrology.The principle of quantum metrology is to make use of the quantum systems or quantum technology to enhance the sensitivity in parameter estimation to beat the standard quantum limit(SQL).Actually the interferometers have been widely and efficiently used as measuring tools in various fields since long ago,such as engineering,products tests in industry,fundamental research for various disciplines,and so on.Typical examples include the large-scale optical interferometer(LIGO)which has successfully captured the signal of gravitational waves,and high precision gravimeter and gyroscope with matter wave interferometers.Thus interferometers will be among the first choices for quantum metrology.Under such background,we came up with two novel quantum precision measurement schemes with interferometry technology.One is photon-number-resolution quantum non-demolition(QND)measurement scheme based on light-atom hybrid interferometer.And the other is an “optical fountain” type quantum interferometer scheme for precision measurement of gravitational acceleration on Earth.The content in this thesis is organized as below:At the beginning,the Raman scattering process for the light in the atoms is used as beam splitters to produce correlated optical signal and atomic spin wave,leading to a hybrid light-atom interferometer.After a second Raman scattering process,the optical signal and atomic spin wave interfere.The intensity of the output signals is sensitive to the phases of both optical field and atomic field.Specifically,the linear Raman scattering processes are used to construct a SU(2)hybrid interferometer and stimulated Raman scattering processes construct an active,SU(1,1)hybrid interferometer.Because of the parametric amplification property of stimulated Raman scattering process,the produced optical signal and atomic spin wave are quantum correlated,causing an improvement of the phase sensitivity of SU(1,1)hybrid interferometer,which can beat the SQL.In the second place,applying the property of atomic phase sensibility of these hybrid interferometers and light intensity related AC-Stark effect in atoms,a scheme for QND measurement for photon numbers or light intensity was devised by us.When the sensitivity of the hybrid interferometer is good enough,this system can be used for photon number counting.The probed light is far-detuned from the resonant frequency of the atoms,so the absorption can be ignored and the photon number of the probed light after the measurement keeps the same.According to the QND criteria came up by Holland et al in 1990,we analysed the feasibility of QND measurement with single-photon-number resolution under lab parameters and test its application in verifications of correlations of twin-beams,as well as state projection property in sequential measurements processes.Finally,we researched the application of quantum enhanced measurement in gravity acceleration measurement of Earth with an “optical fountain” type arrangement,based on the interplay of quantum optics and curved Schwarzschild space theory.Squeezed state and active SU(1,1)interferometer are also analysed to give a better strategy for the measurement of gravity acceleration.The standard quantum limit for gravity acceleration g measurement is defined in our research,and best strategy from those set-ups are shown.This research may provide proof for unification of quantum mechanics and general relativity theory and may provide support for precision cosmological measurement in the future.