【作者】 陆朝阳；

【导师】 潘建伟； 杨涛；

【作者基本信息】 中国科学技术大学 ， 量子信息物理学， 2010， 博士

【摘要】 本论文主要内容是通过操纵多光子纠缠态进行光学量子计算和算法实现的实验研究。我们在实验上发展了一套高亮度的参量下转换纠缠光源和稳定的六光子干涉技术,首次实现了六光子薛定谔猫态和簇态。这些是现今为止实现的光子数最多的纠缠态。通过进一步相干控制极化和空间两个自由度,我们实验实现了由五个光子的极化状态和空间状态相干叠加形成的超纠缠十量子比特薛定谔猫态。这是现今为止量子比特数目最大的纠缠态。为了克服光子损失这一重要的消相干效应,我们在量子线路和簇态量子计算两种模型中分别实现了四比特和五比特的量子容失编码,首次验证了纠正量子比特丢失错误的可行性。最后,我们在国际上首次用光量子比特演示了Shor大数分解算法,并且实验确认了量子计算中多光子干涉和多体纯纠缠的存在。更多还原

【Abstract】 Coherent control of multiple photons with linear optics has been a promising approach to quantum computing. Recent years have witness tremedous progresses, both on theory and experiment on this approach. Major challenges ahead lies in manipulation of an increasing number of entangled photonic qubits, fighting against possible decoherence, and constructing quantum circuits for implementing quantum algorithms.Along this line, this dissertation describes four experiments on multiphoton entanglement and optical quantum computation. We have developed a high-brightness source of entangled photons based on spontaneous parametric down-conversion. Using linear optical networks we are able to entangle them into a six-photon GHZ state, which is the larget photonic Schrodinger cat so far, and a six-photon cluster state, a state-of-the-art one-way quantum computer. Next, we use the hyper-entanglement trick to entangle not only the polarization of the photons, but also their spatial modes. By doing so, we manage to create a six-, eight-and ten-qubit hyper-entangled Schrodinger cat state, expanding the effective Hilbert space up to 1024 dimensions. The third experiment aims to deal with the photon loss error which is a big headache in optical quantum computing. We show both in the quantum circuit model and the one-way model the smallest meaningful quantum codes that are able to tackle the photon-loss problem. Finally, we describe the first optical implementation of Shor’s quantum factoring algorithm. We choose the simplest instance of this algorithm-factorization of 15-and exploit a simplified linear optical network to implement the quantum circuits of the modular exponential execution and semiclassical quantum Fourier transformation.These experiments are necessary steps towards scalable quantum computing with single photons and linear optics.更多还原