Applied Research Of Quantum Information Based On Linear Optics

Due to its special advantages:most of the manipulation can be done at room tem-perature, photons can hardly interact with the environment, it owns good coherence, optical system is one of the most earliest experimental system to used to realize quan-tum communication and quantum information. Quantum measurement is not only the basic postulate, but plays a very important role in the field of quantum information. On the one hand, quantum measurement is the bridge from the quantum world to the clas-sical world, and people never stop to research it by theory and experiment; On the other hand, quantum measurement has been regarded as a kind of technology to develop and use. For instance, in the frame of linear optical quantum calculation, there are several proposals based on the quantum measurement and post selection to bring in nonlinear effect. Furthermore, the theory of weak measurement has gained more and more impor-tance, which was birth at the eighth of the last century. It is not only used to research the basis of quantum mechanics, and to detect the wave function of single photon and pho-ton spin Hall effect, but is widely used as a technology to detect weak signal. During the period to pursue the Ph.D., the author competed several demonstrate experiments about quantum measurement based on linear optical system, including fundamental aspect and applicable aspect. Then, the author also did a quantum simulation experiment in the linear optical system in the real sense, which explored the Kibble-Zurek mechanism in Landau-Zener dynamic model. This work has the followed results:1. We proposed that quantum measurement can lead to the quantum en-tanglement rebirth, and use the frequency freedom to simulate the environment, showed the rebirth of entanglement caused by measurement in experiment.We showed the rebirth of quantum entanglement caused by quantum measurement in the dephasing environment. By twice measurement, the dissipated entanglement can be recovered in some degree. We also point out that even after the phenomenon of entanglement sudden death, it can be rebirth by measurement. Meanwhile, we verified that the entanglement-rebirthed state also has the nonlocality. The result can be used to resist the dephasing in the quantum communication.2. We proposed that polarization-based displaced Sagnac type interferometer can be used to realize partial collapse measurement and recovery, and then we firstly verified the nonlocality of partial collapse measurement and recovery in experimentIn experiment, the partial collapse measurement scheme that we used can make the partial collapse strength be tuned continuously in the whole range. We use polarization-based displaced Sagnac type interferometer to verify the nonlocality of the manipula-tion of partial collapse measurement and recovery. Our results have important signifi-cance in quantum communication and quantum error correcting.3. We proposed an assumption that the white light can be used to estimate phase precisely based on weak measurement, and we pointed out image part of weak value can be bought in by weak measurement evolution, which can decrease the difficulty of experiment. Then, we realized this scheme using a commercial LED light.Firstly, we improved the original scheme of using weak measurement to estimate the phase, and point out that the harsh light source can be avoided by frequency analyze, so that the scheme can be realized using commercial white light source. Our scheme is not dispersion sensitivity, the experiment result is not dependent on Fourier transform. Then we point out that image part of weak value is not necessary, by selecting special input and output states, the weak measurement itself can bring in image part of weak value, which avoid preparing circle polarization state of wide spectrum source. At last, we completed the experiment using commercial LED light, and obtained attosecond-ordered phase change.4. We simulated the Landau-Zener dynamic evolution in the linear optical system, which is the first quantum simulation by linear optical system in the re-al sense. We also studied the Kibble-Zurek mechanism in the non-equilibrium kinetics process.We firstly constructed nine-order polarization-based displaced Sagnac type inter-ferometer. Its interference visibility is as high as0.975±0.008. Then we completed a real quantum simulation experiment by using the interferometer. We observed the evolution process of Landau-Zener kinetics. By tuning the system Hamiltonian, we observed, under different quench condition, the transition from equilibrium to non-equilibrium. It is the first experiment to research Kibble-Zurek mechanism in non-equilibrium kinetics process.