Highly Bright Quantum Light Source And Its Applications

Quantum information is an emerging frontier interdisciplinary science based on fundamental physics principles of quantum mechanics combinined with math and computer science.It has made great revolutionary changes to information security and computation power of modern technology.For quantum information processing based on photons,generation of highly bright quantum light and engineering the quantum state play an important role in such progress.The typical way to generate quantum light is spontaneous parametric down conversion(SPDC)process.This thesis describes two schemes based on two different non-linear crystals and their applications in quantum information processing.The main results include:1.Quantum communication through seawater channel.We experimentally demonstrated quantum communication through free-space seawater channel with a length of 3.3m for the first time.We sent six polarization basis coded single photon state through the channel and obtained an average state transfer fidelity over 98% and showed that seawater channel is almost identical to perfect channel.Meanwhile we demonstrated that entanglement photons can survive after traveling through seawater and we can still observed anti-correlation of the entanglement state and achieved a Bell test voilation up to 33 standard deviations.We can expect that the seawater farther from the coastline,which contains less suspended particulate matter and therefore has much lower attenuation,may promise longer transmission distance for photons in blue-green window.Combined with quantum repeater,it may realize global quantum communication network.2.Non-classical correlation of two photons in two-dimesional photonic lattices.We used fs-laser direct writing to fabraicte the two-dimensional photonic lattices in pure borosilicate and for the first time observed non-classical correlation of two identical photons.The overlap between measured and simulated distribution is S = 0.890 ± 0.001 and S = 0.916 ± 0.001 for identical and temporal delayed photons.A good match between measured and simulated results verifies the capacity of robust and precise on-chip manipulation of quantum states at single-photon level.We also observed a Cauchy-Schwarz inequality violation up to 20 standard deviations due to bosonic bunching nature which only occurs in the quantum regime.Our threedimensionally fabricated photonic chip associated with multi-photon-chip interface may serve as a good candidate in exploring quantum simulation in a more complex regime.