Experimental Research On Quantum Information Processing Based On Micro-nano Optical Waveguide

The development of quantum computing and quantum theory provides important new-principle solutions,which deal with the limited chip size and the inapplicability of classical physical principles in the post-Moore era,and can theoretically meet the future demand for higher information content.The miniaturization and integration of quantum information systems are bound to become important research areas in the field of quantum information and quantum computing.In this thesis,we use the micro-nano optical waveguide structure to study the quantum information processing process of the integrated optical system in different structures.The main research contents are:1.We studied the transmission of quantum information in integrated micro-nano structures.Transmission of two-photon polarization-entangled states in a surface plas-mon waveguide of several microns long were realized,and the entanglement properties can be well maintained.We measured the two-photon interference curve by using a tunable phase plate,and evaluated the effect of the overall loss of the system on quan-tum sensing.Our work provides fundamental theoretical and experimental results for quantum imaging or quantum sensing in lossy systems or surface plasmon structures,aiming for breaking the standard shot-noise-limit.2.We briefly introduced the mechanism of photo-induced refractive index changes in transparent media materials using the femtosecond laser direct writing technolgies,which can be used to prepare optical waveguides.Based on the femtosecond laser direct writing of glass waveguide system,we demonstrated the basic performance of polarization-independent optical waveguide devices and the possibility of being ap-plied to quantum information processing;we demonstrated the logic function of the path-encoded quantum CNOT gate;by cascading the path-encoded quantum CNOT gate and a single-qubit quantum gate,we demonstrated the possibility of generating path-encoded Bell entangled states and the scalability of the structure.Our results show that we can use femtosecond laser direct writing technology to realize basic components of quantum circuits with high precision,and lay the foundation for the future study of large-scale quantum circuits or quantum simulations.3.Under the paraxial approximation condition,we showed that the propagation of electromagnetic field in the optical waveguide satisfies the Schrodinger form of propa-gation equation.Based on this,we discussed the similarities between the transmission behavior of light in the waveguide and the electronic behavior in the solid.Tight-binding approximation model was constructed to describe the transmission behavior of light in waveguide arrays.The transportability of the parameters in the two coupled waveguide systems to the complex array structure was studied.Based on our established intuitive theoretical results,we reviewed and discussed many applications of optical waveguide array systems.Furtherly,we experimentally prepared a one-dimensional topological non-trivial waveguide array structure using femtosecond laser direct writing technol-ogy and studied edge states of this system.Evolution of the edge states and topological phase transition in this system were experimentally observed.Based on our basic theo-retical and experimental research on the propagation behavior of light in the waveguide array,we will further investigate higher dimensional or more complex physical models in the near future.4.Based on the honeycomb hexagonal lattice structure,we introduced a two-dimensional topological insulator with different sublattice energies.Firstly,by analyz-ing energy bands of the model,a valley-related topological Chern number was obtained Secondly,by constructing photonic crystal structures with different valley Chern num-bers,we theoretically predicted valley-related directional transmission of light at the interfaces.We then constructed a valley-related wave splitting structure based on this valley-related selective coupling mechanism.Thirdly,we specially designed a harpoon-shaped beam splitter structure,in which the spitting ration is 1:1 at the wavelength of 1550 nm.We demonstrated the two-photon quantum interference in this valley-related topological beam splitter structure.Furthermore,we constructed a simple quantum cir-cuit to verify the generation of path entangled states in the structure.This work provides a pioneering new idea for the use of valley-related topological insulator structures in quantum information processing.