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多光子量子纠缠技术及其应用
【作者】 徐凭；
【作者基本信息】 中国科学技术大学 ， 量子信息物理学， 2012， 博士
【摘要】 量子信息技术目前已经成功地将量子力学基本原理应用至密码学、计算机科学、度量学等学科领域,不过多数情况下量子信息是以光子为载体,因而多光子纠缠操纵技术对构建量子信息系统便显得尤为重要。通常我们基于自发参量下转换技术产生高质量的极化纠缠光子对,而进一步利用超纠缠,能够使得量子信息同时加载于光子的极化模式和空间模式。这里我们实验制备了超纠缠十量子比特薛定谔猫态；基于四光子六量子比特态实现了量子受控非门；利用非团簇态实现了基于测量的量子计算；基于不同的六量子比特图态实现了Bell不等式测量。利用改进的新型量子纠缠光源,首次成功实验制备了八光子薛定谔猫态。同时,我们对利用PPKTP晶体制备纠缠光源进行了研究。
【Abstract】 Recent advances in quantum information processing have enabled practical applications of quantum mechanics in various fields such as cryptography, computation, and metrology. Most of these applications use photons as carriers of quantum information. Therefore, engineering the quantum state of photons is essential for the realization of quantum information schemes.A practical technique to generate high-quality polarization entangled photon pairs is spontaneous parametric down conversion (SPDC) process. Furthermore, quantum information can be encoded in the polarization mode and spatial mode of photons by making use of hyper-entanglement. We experimentally demonstrated a hyper-entangled ten-qubit "Schrodinger cat" state. We experimentally realized a Controlled-NOT gate with four-photon six-qubit cluster states. We experimentally demonstrated measurement-based quantum computing beyond the cluster-state model. We experimentally implemented Bell inequality tests of four-photon six-qubit graph states. By using new ultra-bright sources of entangled photon pairs, the eight-photon "Schrodinger cat" state was created for the first time. Meanwhile, we designed the entangled photon source based on PPKTP crystal.