Experimental Investigation Of Continuous-variable Higher Order Mode Non-classical Optical Field

Non-classical optical field,especially squeezed light and entanglement are important resource in quantum information processing.It?s generation,control,transmission and measurement are playing an important role in the development of quantum communication and quantum metrology.At present,most research focus on the fundamental mode,the intensity and phase patterns of higher order mode is more complex.Meanwhile,the characteristics of different modes and their orthogonality provide more choices and applications for quantum information processing and precise measurement.For example,rotation measurement,micro-displacement measurement and super-resolution imaging using higher order modes.In addition,the higher order mode can be applied to multi-channel quantum computing and quantum super-dense coding,improve the channel capacity.Besides the freedom of spatial mode,other degrees of freedom such as polarization and frequency are also concerned.High dimensional entanglement provides higher information density and security than two dimensional entanglement,making it more prominent in quantum communication.In the case of high noise environment or the random number generation device has controlled,high dimensional entanglement can complete the work that ordinary entanglement cannot.Compared with ordinary entanglement,high dimensional entanglement can greatly reduce the probability of being successfully cloned,and the higher the dimension of the system,the lower the probability of being successfully cloned.Furthermore,high dimensional entanglement can optimize the quantum computing system and accelerate the execution of quantum computing.Therefore,the research in theory and experiment of continuous variable high order mode squeezed light and entanglement are important to quantum physics and quantum information.The main contents in this thesis are as follows:1.Based on the temperature sensitivity of entanglement in type-II NOPA,a method to exploiting the photothermal effect locking the crystal temperature is relized.A significantly enhanced stability is present with crystal temperature locking.Faster and more accurate temperature control was accomplished compared with current temperature controllers.A long-term stable entanglement source at 5.4 d B lasting up to 2 hours was achieved,the fluctuation of the degree of entanglement was 0.13 d B.2.Beam shaping system(BSS)can be used to transfer squeezing from the fundamental mode to an arbitrary complex amplitude distributed mode,the max mode conversion efficiency is 0.77.With this method,different spatial modes can be generated simply by applying different holograms on the spatial light modulators.Our system does not disrupt the quantum properties of the light.As a quantitative benchmark for the generated mode quality,we analyze the mode purity by comparing the generated mode and corresponding theoretical standard mode.3.The high dimensional entanglement in type-II NOPA is analysed.Through a single type-II NOPA generated five pairs entanglement based on optical frequency comb,the degree of entanglement is-4.5d B.Through the spatial mode manipulate technique,control the spatial mode of NOPA,generated the high dimensional entanglement with three different degrees of freedom.The creative works in the thesis are as follows:1.A method to exploiting the photothermal effect locking the crystal temperature is relized.A long-term stable entanglement source at 5.4 d B was achieved.The fluctuation of the degree of entanglement within two hours was 0.13 d B.2.Beam shaping system(BSS)can be used to high efficiency transfer squeezing from the fundamental mode to an arbitrary complex amplitude distributed mode.3.The high dimensional entanglement with three different degrees of freedom is realized by using the higher order mode NOPA multimode resonance technique.