Experimental Investigation Of Photonic Quantum Walks

Quantum walks are similar to classical random walks in natural physics,but they are superior to classical random walk due to quantum interference effects.A very useful tool for the study of quantum algorithms in quantum information processing is the quantum walk,which of course plays an important role as a universal quantum simulation platform for controlling dynamical processes in a wide variety of physical systems and for verifying some theoretical problems in quantum mechanics.Although it has been widely studied in theory,the experimental exploration of quantum walk is still in its infancy.In this paper we focus on the implementation of single-photon quantum walk using an optical fiber ring experimental structure,followed by a discussion of the effect of external experimental conditions on the number of steps,the identification of the optimal experimental solution and the simulation of Anderson localization using quantum walk platform.The main points of this paper are as follows:1.The working principle of the linear optical crystals and the wave plates is introduced in detail,then we test an experimental setup for achieving the location spatial distribution of photonic quantum walk using only linear optical crystals,and verify the feasibility of implementing photonic quantum walk with linear optical crystals and analyze the strengths and weaknesses of such a setup.2.The experimental structure of a new optical fiber loop using linear crystals and special single-mode fibers to achieve one-dimensional discrete-time photonic quantum walk is highlighted,and the results of five steps of photonic quantum walk were successfully obtained,which were in good agreement with the theoretical results,and the feasibility of this experimental setup is successfully verified.3.The reasons for limiting the number of photonic quantum walk's steps in the optical fiber loop experimental setup are explored.The effects of the beam splitter transmittance ratio,fiber length,repetition frequency of the pulsed laser and digital delay generator on the number of quantum walk steps were analysed in turn.We have successfully identified the most suitable experimental conditions and achieved a 15-step photonic quantum walks,and some of its properties were discussed.4.We propose an original experimental structure for a fiber-optic loop and introduce an electro-optical modulator,and we try to use quantum state tomography techniques to correspond the externally triggered electro-optical modulator voltage to its phase delay.We then simulated the Anderson localization phenomenon and found that the probability distribution is completely localization around the origin.