Experimental Generation Of Photonic Entanglement State And Photonic Quantum Computation

Multi-particle entanglement resources are the most crucial resources in the quantum world.In quantum physics,the preparation of multi-particle entangled states with more particles has always been the most attractive and stirring research direction.In this paper,the ultra-high brightness entangled light source based on the spontaneous parametric down-conversion was designed and the Ten-Photon Entangled State was successfully completed,which is by far the most entangled state of photons.This provides a key boost to the realization of more complex quantum computing,quantum simulation and quantum storage in the future.In quantum computing,mastering the technique of producing multi-photon entangled states is an important capability because we can apply to quantum algorithms to prepare photonic qubits for acceleration.In this paper,we use the prepared fourphoton entangled state to realize quantum machine learning,which is the first machine learning based on quantum entanglement in the world.The multi-dimensional vector information is encoded on the polarization degree of freedom of the optical qubit and then passed through an auxiliary qubit projection measurements to get machine learning answers,which we achieved quantum machine learning.Due to the use of quantum entanglement and quantum superposition properties in the encoding of information,exponential quantum acceleration can be achieved compared to classical computers.When the multipartite entangled state is prepared,we often also want to know the entangled nature of the states,so we need to use quantum tomography.However,this technique becomes very difficult when the number of particles reaches a certain scale.In this paper,we introduce Concurrence entanglement metric theory is used to expand the original entangled state by using an embedded quantum simulator.Non-observables that can not be directly measured in the entangled state evolution over time are converted into observable quantities by an auxiliary optical quantum bit,The Pauli matrix measurement operation reads it out,which greatly simplifies the entire measurement process.This method can also be extended to the study of more entangled states for qubits.There are many kinds of multi-photon entangled states,such as W states and GHZ states.When we study the entangled nature of entangled states,we often need to do entanglement classification.In this paper,the concept of entangled polyhedron and the concept of entangled state distillation are combined for the first time by measuring the state of a single photon and using this measurement for feedback quantum control to achieve entanglement distillation operations,we can uniquely classify different entanglements from iterative distillation results.Quantum self-testing is a device-independent way to certify quantum states and measurements using only the input-output statistics,with minimal assumptions about the quantum devices.Because of the high demand on tolerable noise,however,experimental self-testing was limited to two-photon systems.Here,we demonstrate the first robust self-testing for multiphoton genuinely entangled quantum states.We prepare two examples of four-photon graph states,the Greenberger-Horne-Zeilinger states with a fidelity of 0.957(2)and the linear cluster states with a fidelity of 0.945(2).Based on the observed input-output statistics,we certify the genuine four-photon entanglement and further estimate their qualities with respect to realistic noise in a deviceindependent manner.