Broadband Tunable Entangled Photons And The Evolution Of Spatial Correlation In Curved Space-time

In recent years,quantum information technology is gradually moving out of the laboratory and into practical applications.For example,quantum communication has been expanded from the 100 km range demonstrated by the laboratory to the inter-city network and even successfully achieved ground-air communication.Therefore,higher quantum light sources such as single-photon sources as their core resources are required.The research and preparation of lightweight,integrated,high-quality,wide tuning single-photon sources and entangled light sources are particularly important.On the other hand,the time-space bending effect must be taken into consideration when the quantum information technology is extended to larger space-time.Quantum information considering the relativistic effect shows many novel features,making the related research of quantum information science in curved spacetime become very popular in recent years.This dissertation starts from the above two aspects,and concentrates on the study of the wide tuning heralded single-photon source based on miniaturization and the study of the evolution law of entangled photons transverse position correlation in curved space-time.The main results obtained are as follows:1.The wavelength tuning schemes for entangled photons and heralded single photon sources based on a periodic polarized titanium diffused lithium niobate waveguide spontaneous parameter down conversion process is proposed and studied.The effects of temperature,polarization period and wavelength of pump light on the entangled photon wavelengths produced by different types of spontaneous parameter down conversions are calculated in detail.Three wide tuning heralded single photon source schemes based on pump light tuning were proposed,which can achieve wavelength tuning in the 200nm range near 800nm(Pump light tuning 2nm),wavelength tuning in the 800nm range near 1550nm(Pump light tuning 10nm),and wavelength tuning in the 1000nm range(Pump light tuning 5nm)covering the above both major wavelengths simultaneously.2.Development of chip type heralded single photon source and engineering design.Using laser diodes,blazed gratings,mirrors,etc.,Grating external cavity semiconductor tunable laser are constructed as a pump light source of heralded single photon sources.A photonic source chip based on a periodically polarized titanium-diffused lithium niobate waveguide was prepared.By optimizing the polarization period and waveguide process parameters through multiple experiments,a high-yield lithium niobate waveguide photonic source chip was obtained.3.The evolution of entangled photons transverse position correlation in the constant Gaussian curvature space-time is studied.The evolution of the transverse position correlation of the entangled photon pair in the positive Gaussian curvature space-time,negative Gaussian curvature space-time and mixed curvature space-time is calculated separately.In the positive Gaussian curvature space-time,the evolution of the transverse position correlation presents periodicity and symmetry.In the negative Gaussian curvature space-time,the evolution of the transverse position correlation will tend to be a stable state of correlation.When one photon is in positive curvature space-time and the other is in negative curvature space-time,then the evolution law will be affected by two subspace-time characteristics,that is,the characteristics of periodicity and correlation state remain,but they will affect each other and interact.4.The ghost imaging phenomenon of entangled photons in positive Gaussian curvature space-time is studied.Based on the properties of the periodic recurrence of the transverse position correlation of entangled photons in the space of positive Gaussian curvature,the phenomenon of lensless correlation imaging in positive Gaussian curvature is found.The imaging formula are obtained,the resolution is characterized,and "single-slit" and "double-slit" imaging in the two-dimensional space is simulated.