拓扑量子纠错的实验演示及锂钾玻色费米双超流系统的实验实现

发布时间：2018-06-25 00:35

  本文选题：多光子纠缠 + 拓扑量子纠错　； 参考：《中国科学技术大学》2016年博士论文

【摘要】：本文主要阐述了两个方面的工作。第一部分主要研究了多光子纠缠系统中实现拓扑量子纠错。纠缠是量子计算的核心资源。在所有的系统中,线性光学系统由于其操纵简单,环境耦合小,退相干时间长等优点一直受到研究者的青睐。由于量子系统不可避免的和环境耦合,退相干效应使得量子比特的制备和操作产生错误。所以量子计算方案需要考虑容错性。拓扑量子纠错利用了簇态的拓扑性质,只需要最近邻相互作用的纠缠粒子,就可以达到约为1%的容错阈值,比之前的工作提高了三个数量级。而簇态是一种具有高纠缠度的多体量子态,能够作为通用资源实现单向量子计算。我们在发展了高亮度八光子纠缠源的基础之上,制备了具有拓扑性质的簇态,实验上成功演示了拓扑量子纠错。我们制备的八光子拓扑簇态的纠缠目击测量期望值为-0.105士0.023,超过了经典极限4.5倍标准偏差。利用八光子簇态,我们实验演示了拓扑量子纠错可以完全纠正一个单比特错误,而且在所有比特有等概率出现错误的情况下,能够有效的降低错误概率。我们的工作为实现大规模的容错量子计算翻开了新的篇章。本文的第二部分主要讲述了玻色费米超冷原子混合气体的实验装置搭建工作。该套装置可以将41K-6Li的混合稀薄气体冷却至量子简并。冷却的过程包括塞曼冷却器,二维磁光阱,三维磁光阱,UV磁光阱,灰色光学黏团,光泵浦,磁传输,光塞磁阱中的蒸发冷却和光阱中的蒸发冷却,运用了大部分已知的最先进的冷却技术。在光塞磁阱中,我们能够获得1.4×105个41K原子,温度为72.4%Tc；和5.5×105个6Li原子,温度为25%TF。在光阱中,我们取得了更好的蒸发冷却效果,最终获得了1.8×105个41K原子,基本没有热原子成分；和1.5×106个两自旋态混合的6Li原子,温度为7%TF,世界上首次实现了异核玻色费米双超流。基于此,我们将玻色费米双超流转动起来,并且观察到了玻色费米相互耦合的量子化涡旋阵列。我们还观测了涡旋的产生和演化,发现了很多不寻常的现象。这些结果会为相关的理论工作提供实验的支持,无疑会促进相关理论的发展。
[Abstract]:This paper mainly describes two aspects of the work. In the first part, the realization of topological quantum error correction in multiphoton entangled systems is studied. Entanglement is the core resource of quantum computing. In all systems, linear optical systems have been favored by researchers because of their simple manipulation, small environmental coupling and long decoherence time. Due to the inevitable and environmental coupling of quantum systems, the decoherence effect causes errors in the preparation and operation of quantum bits. Therefore, the scheme of quantum computing needs to consider fault tolerance. The topological quantum error correction takes advantage of the topological properties of the cluster states. Only the entangled particles in the nearest neighbor interaction can reach a fault-tolerant threshold of about 1%, which is three orders of magnitude higher than the previous work. The cluster state is a multibody quantum state with high entanglement, which can be used as a universal resource for unidirectional quantum computation. Based on the development of a high luminance eight-photon entanglement source, we have prepared a cluster state with topological properties. We have successfully demonstrated the topological quantum error correction in experiments. The entangled eyewitness value of the 8-photon topological cluster states is -0.105 卤0.023, which exceeds the classical limit 4.5 times the standard deviation. Using the eight-photon cluster state, we demonstrate that topological quantum error correction can completely correct a single bit error, and can effectively reduce the error probability when all bits have the same probability error. Our work opens a new chapter for the implementation of large-scale fault-tolerant quantum computing. The second part of this paper mainly describes the construction of the experimental device for the Bose Fermi supercooled atomic mixture gas. The device can cool the mixed rarefied gas of 41K-6Li to quantum degeneracy. The cooling process includes Zeeman cooler, two-dimensional magneto-optic trap, three-dimensional magneto-optic trap UV magneto-optic trap, gray optical glue, optical pump, magnetic transmission, evaporative cooling in optical plug magnetic trap and evaporative cooling in optical trap. Most of the most advanced cooling techniques are used. We can obtain 1.4 脳 105 41K atoms and 5.5 脳 105Li atoms at 72.4 Tc and 5.5 脳 105 Li atoms at 25 TFs. A better evaporative cooling effect has been obtained in the optical trap, with 1.8 脳 10 5 41K atoms, almost no thermal atom composition, and 1.5 脳 10 6 spin state mixed 6Li atoms at a temperature of 7TF.The heteronuclear boson Fermi double superflow has been realized for the first time in the world. Based on this, we rotate the Bose Fermi double superflow and observe the quantum vortex array of bosonic Fermi coupling with each other. We have also observed the generation and evolution of vortices and discovered many unusual phenomena. These results will provide experimental support for relevant theoretical work and will undoubtedly promote the development of relevant theories.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O413
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本文编号：2063697