Preparation Of Entangled States Based On Quantum Dots Coupled With Optical Microcavity

Quantum entanglement is one of the important resources in quantum information.In the long distance communication,entangled photon system is the first choice to create quantum channel,which can complete some important communication work,such as quantum teleportation,quantum secure direct communication.GHZ and W states are common in multi-qubit entangled states.Compared with GHZ state,the entanglement of W state is more robust and less easily broken.In addition,a hyper-entangled state with multi-DOF is an important resource,which can improve the channel capacity and speed up the quantum computation.Compared with the other quantum information carriers,photons have the advantages of faster transmission speed and lower cost.Because it is difficult to realize the effective interaction between photons at the single photon level based on the linear standard model,the success probability of quantum entanglement is limited.However,the probability of success can be improved by nonlinear interaction.Charged semiconductor quantum dots coupled with single or double-sided cavities are valuable optical devices to realize the nonlinearity between photons.Quantum dot is easy to operate,and its application can be improved by coupling with optical microcavity.The coupling system of quantum dot and optical microcavity has good ductility,and the quantum dot in the microcavity can store quantum information for a long time by using a long time of electron spin coherence.In this thesis,we consider the preparation of entangled states with the aid of a single-sided cavity quantum dot system.First of all,we introduce the basic principle of single-side cavity quantum dot system in the second section of the third chapter.In the third section,we describe the preparation process of hyper-entangled perfect W state with three steps: the first step is to prepare three-photon polarization-entangled perfect W state,the second step is to prepare three-photon path-entangled perfect W state,and the third step is to produce three-photon hyper-entangled perfect W state.In the fourth chapter,we employ the quantum dot and optical microcavity coupling system to construct the non-destructive detector and prepare the GHZ state of three particles.Then we increase the number of non-destructive detectors and H gates to prepare the GHZ state of N particles.