Investigation On Application Of Squeezed Vacuum State Light Field At A Telecommunication Wavelength In Optical Precision Measurement Based On Fiber Structure

Optical precision measurement device based on fiber structure is the foundation of the development of optical fiber sensing technology.Because it has the advantages of simple structure,low cost,high precision,it can be flexibly used in various measurement environments and has a wide range of applications in the actual optical precision measurement.Due to the limitation of the shot noise of the optical field,the measurement accuracy of optical precision measurement has quantum limit,that is,standard quantum limit(SQL).The noise fluctuation of one quadrature component of the squeezed vacuum state light field is lower than the shot noise limit(SNL).The squeezed vacuum state light field can be used for quantum enhanced optical precision measurement,and the measurement accuracy can break through the SQL.The measured frequency of many physical quantities,such as tiny vibration and strain on the surface of objects,is usually in the range of k Hz.Therefore,low-frequency squeezed vacuum state light field is the best quantum light source to realize quantum enhanced optical precision measurement.In the process of realizing quantum-enhanced optical precision measurement based on fiber structure,the squeezed vacuum state light field will occur decoherence because of the interaction with the environment,that will reduce the sensitivity of quantum-enhanced precision measurement.When squeezed vacuum state is used in fiber channel transmission of various quantum protocols,the decoherence will also affect the implementation of quantum protocols.In this paper,low frequency stable output quadrature phase squeezed vacuum state light field and quadrature amplitude squeezed vacuum state light field at a telecommunication wavelength are prepared.Secondly,the prepared squeezed vacuum state light field is applied to the precision measurement of the amplitude and phase low-frequency signal using the measurement device based on fiber structure.The quantum enhanced phase and amplitude low-frequency signal measurement is realized.Finally,a four-channel error correction scheme based on optical fiber correlated noise channel is proposed to realize the quantum error correction of the squeezed vacuum state light field in optical fiber.The main research contents of this paper are as follows:1.The stable output squeezed vacuum state light field at a telecommunication wavelength is prepared.The Optical parametric oscillator(OPO)is used to generate the squeezed vacuum state light field at a telecommunication wavelength.The squeezing angle of the squeezed vacuum state and the relative phase between the squeezed light and the local oscillator light are locked using the coherent control technique.The quadrature phase squeezed vacuum state of squeezing degree is 5.2±0.5 d B and the quadrature amplitude squeezed vacuum state of squeezing degree is 5.0±0.5 d B stably output in the frequency range of 40 k Hz to 200 k Hz.The squeezing degree of the quadrature phase squeezed vacuum state and the quadrature amplitude squeezed vacuum state is about 2.7±0.5 d B at the frequency of 6 k Hz.2.The quantum enhanced phase signal and amplitude signal at low-frequency are measured by using the prepared squeezed vacuum states.The low-frequency quadraturephase squeezed vacuum states is injected into the vacuum port of the fiber Mach-Zehnder interferometer,and the low frequency signal measurement which breaks the SNL is realized,the signal-to-noise ratio is increased by more than 3.5d B at the frequency range of 40-200 k Hz,and 2.3 d B at 20 k Hz.The low-frequency quadrature-amplitude squeezed vacuum states and a weak coherent light are coupled into a single mode polarization-maintaining fiber as signal light.The signal light is detected by a balanced homodyne detectors system of the fiber structure.In the frequency range of 60-200 k Hz,the measurement sensitivity of the amplitude signal is improved by 2 d B compared with that of SNL.3.A four-channel quantum error correction scheme based on optical fiber correlated noise channel is designed.The influence of optical fiber transmission distance,light power of Local oscillator,and the correlated degree of optical fiber correlated noise channel on reducing the decoherence of squeezed vacuum state optical field in optical fiber channel is theoretically studied.