發(fā)布時間：2018-06-25 00:35

  本文選題：多光子糾纏 + 拓?fù)淞孔蛹m錯　； 參考：《中國科學(xué)技術(shù)大學(xué)》2016年博士論文

【摘要】：本文主要闡述了兩個方面的工作。第一部分主要研究了多光子糾纏系統(tǒng)中實現(xiàn)拓?fù)淞孔蛹m錯。糾纏是量子計算的核心資源。在所有的系統(tǒng)中,線性光學(xué)系統(tǒng)由于其操縱簡單,環(huán)境耦合小,退相干時間長等優(yōu)點一直受到研究者的青睞。由于量子系統(tǒng)不可避免的和環(huán)境耦合,退相干效應(yīng)使得量子比特的制備和操作產(chǎn)生錯誤。所以量子計算方案需要考慮容錯性。拓?fù)淞孔蛹m錯利用了簇態(tài)的拓?fù)湫再|(zhì),只需要最近鄰相互作用的糾纏粒子,就可以達到約為1%的容錯閾值,比之前的工作提高了三個數(shù)量級。而簇態(tài)是一種具有高糾纏度的多體量子態(tài),能夠作為通用資源實現(xiàn)單向量子計算。我們在發(fā)展了高亮度八光子糾纏源的基礎(chǔ)之上,制備了具有拓?fù)湫再|(zhì)的簇態(tài),實驗上成功演示了拓?fù)淞孔蛹m錯。我們制備的八光子拓?fù)浯貞B(tài)的糾纏目擊測量期望值為-0.105士0.023,超過了經(jīng)典極限4.5倍標(biāo)準(zhǔn)偏差。利用八光子簇態(tài),我們實驗演示了拓?fù)淞孔蛹m錯可以完全糾正一個單比特錯誤,而且在所有比特有等概率出現(xiàn)錯誤的情況下,能夠有效的降低錯誤概率。我們的工作為實現(xiàn)大規(guī)模的容錯量子計算翻開了新的篇章。本文的第二部分主要講述了玻色費米超冷原子混合氣體的實驗裝置搭建工作。該套裝置可以將41K-6Li的混合稀薄氣體冷卻至量子簡并。冷卻的過程包括塞曼冷卻器,二維磁光阱,三維磁光阱,UV磁光阱,灰色光學(xué)黏團,光泵浦,磁傳輸,光塞磁阱中的蒸發(fā)冷卻和光阱中的蒸發(fā)冷卻,運用了大部分已知的最先進的冷卻技術(shù)。在光塞磁阱中,我們能夠獲得1.4×105個41K原子,溫度為72.4%Tc；和5.5×105個6Li原子,溫度為25%TF。在光阱中,我們?nèi)〉昧烁玫恼舭l(fā)冷卻效果,最終獲得了1.8×105個41K原子,基本沒有熱原子成分；和1.5×106個兩自旋態(tài)混合的6Li原子,溫度為7%TF,世界上首次實現(xiàn)了異核玻色費米雙超流�；诖�,我們將玻色費米雙超流轉(zhuǎn)動起來,并且觀察到了玻色費米相互耦合的量子化渦旋陣列。我們還觀測了渦旋的產(chǎn)生和演化,發(fā)現(xiàn)了很多不尋常的現(xiàn)象。這些結(jié)果會為相關(guān)的理論工作提供實驗的支持,無疑會促進相關(guān)理論的發(fā)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 鹵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.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：O413
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本文編號：2063697