Generation And Application Of Low-frequency Squeezed Light At Telecommunication Band

Continuous variable(CV) squeezed states of light are an important quantum resource,which have been used in continuous variable quantum information and quantum computing,as well as the precision measurement beyond the shot noise limit.Meanwhile the squeezed states of light can improve the sensitivity of the laser interferometer gravitational wave detector by injecting into the dark port of the detector.Continuous variable squeezed states at the telecommunication wavelength of 1550 nm is an important quantum resource based on the practical application of optical fiber.Because the optical power attenuation of light in standard telecommunication fibres is lowest at 1550 nm,and the source is highly compatible with the existing optical fiber communication system.So it is necessary to achieve CV squeezed states at the telecommunication wavelength of 1550 nm.As the demand and application of CV squeezed states of light,the generation of CV low-frequency squeezed states of light have been widely researched and develope by scientists.The CV low-frequency squeezed states can be obtained by degenerate optical parametric oscillator,which is an key quantum resource and broadens the range of applications when using fiber-based setups for quantum-enhanced sensing,especially in the low-frequency range.The academic paper studies the generation and application of continuous variables low-frequency vacuum squeezed states at the telecommunication wavelength of 1550 nm.The main contents are as follows:1.The first chapter briefly reviews the background of the squeezed states of light and application prospect,especially including the motivation and recent international advances of the low-frequency squeezed states of light.2.The second chapter introduces the theory about the generation of the squeezed states by using optical parametric down-conversion,quasi phase matching technology of nonlinear crystal and balance homodyne detection technology of detecting squeezed states of light.Then CV low-frequency vacuum squeezed states at 1550 nm were experimentally generated by using a type-I degenerate optical parametric oscillator(DOPO)below the threshold.The low-frequency squeezed states were generated at analysis frequency range from 50 kHz-900 k Hz.A maximum squeeze degree of 5.0 dB is obtained at analysis frequency of 200 k Hz.A 2.0 d B squeezed light is obtained at the lowest analysis frequency of 50 kHz.When the analysis frequency is lower than 50 kHz,the squeezed states of light output from the DOPO were submerged because the extra noise exists,which comes from the relaxation oscillation's noise of pump field in audio segments,the parasitic interference in light path,the higher electronics' noise caused by the detector in the audio segment and so on.3.The third chapter firstly introduces the types and the applications of interferometer,and then depicted the application and research status of CV squeezed states of light being injected into the interferometer.We built the fiber Mach-Zehnder interferometer(MZI)firstly.And then the generated vacuum squeezed states at 1550 nm were injected into the dark port of MZI.An improvement of ~1dB relative to the shot noise level is achieved.