Experimental Verification And Application Of The Fundamental Principles Of Quantum Physics

Born in the early 20 th century,quantum physics refers to phenomena and features in microscopic system that cannot be explained through classical physics.One of the hallmarks that distinguishes quantum physics from classical physics is coherence.Coherence is the basis for phenomena such as quantum interference and quantum entanglement,which can be applied to quantum information science.Quantum information science is a new field of research,which can use quantum resources such as coherence to carry out a series of important tasks such as information storage,transmission,computation,etc.,so as to solve the problems that cannot be solved in the field of classical physics.The well-known quantum algorithms such as the Shor algorithm for prime factorization and the Grover search algorithm can be used to illustrate the potential capabilities of quantum computation.The foundation of quantum information science is inseparable from the study of the basic problems of quantum physics.Only by starting from the scientific basis of quantum physics and explaining counterintuitive phenomena can we continue to bring new ideas and concepts to more technologies and applications.In the early days after the birth of quantum physics,researchers often designed thought experiments to explain some of the fundamental principles in quantum physics.However,we need real experiments to validate some of the ideas put forward by early scientists and intuitively understand quantum physics.At the end of the 20 th century,a large number of real experiments based on linear optics emerged to support fundamental concepts in quantum physics.Until today,linear optics has developed very well,and its advantage lies in having multiple controllable degrees of freedom while maintaining coherence for a long time.These ensure that it not only underpins the testing of the fundamental principles of quantum physics,but also drives the realization of quantum computation.Combined with the above,starting from linear optics,through the preparation of single photons,this paper experimentally verifies a number of fundamental principles in quantum physics,including uncertainty relationships,quantum contextuality,etc.At the same time,this paper also focuses on the relevant applications of quantum physics,including the observation of the dynamics of an ergodic quantum protocol and the implementation of deterministic search algorithms.The specific research content is as follows:(1)Quantum information processing can often be expressed as the coherent superposition initial state,which evolves to obtain the corresponding final state and is finally measured.Starting from this idea,the study introduces the use of photon polarization and path freedom to encode quantum states in linear optical systems.The preparation of quantum states,the evolution of systems,and the measurement of final states are realized by using linear optical elements.This laid the foundation for subsequent research content.(2)Uncertainty relations are one of the most important fundamental concepts of quantum physics,and this study introduces experiments to test a set of uncertainty relations for two unitary operators.The uncertainty relation is derived by replacing the Cauchy-Schwartz inequality with the arithmetic-geometric mean inequality.In high-dimensional systems,the lower bound of this uncertainty relation goes beyond the well-known lower bounds in previous literature.And this lower bound can be further strengthened by the symmetry of permutation.The measurement of the uncertainty relation of unitary operators becomes an effective tool for testing the quantumness of physical systems.(3)The state-independent contextuality in four-dimensional Hilbert space is illustrated by single-photon experiments.The effect of event definition on the emergence of nonclassical correlations under the condition of using coherent light field is analyzed.Subsequently,this study further tests the noncontextual inequality in the form of entropy instead of the linear probability inequality,and the negative information unique to quantum physics can be detected from the experimental data.Testing of quantum contextuality opens up new avenues for distinguishing quantum physics from classical physics.(4)In terms of the application of quantum physics,the experiment implements an ergodic quantum protocol.It is shown that initial states from any small area on the Bloch sphere will cover the entire space of the Bloch sphere after a limited number of iterations.The quantum states is reconstructed through tomography,which further illustrates the ergodicity of the quantum dynamics.(5)Theoretically,a quantum space search algorithm is proposed by alternately using continuous-time quantum walks and phase-flip operators.The number of oracle queries used by the search algorithm is the same as that of the Grover algorithm,indicating that it reaches the optimal boundary of the Grover algorithm.We experimentally implemented this deterministic search algorithm by applying a quantum walking platform.Evidence is provided for quantum walking as a universal tool for quantum information processing.The experiments mentioned in the article are based on linear optical systems,demonstrating that linear optics can be a candidate for general quantum information processing techniques.In this thesis,some research results in the application fields and basic fields of quantum physics are introduced.These research results can provide new insights into interdisciplinary fields such as quantum information and quantum computation.