量子力学发展与应用前沿 量子计算与通讯探讨数则

        量子力学发展与应用前沿  量子计算与通讯探讨数则
      
     Experimental Quantum Error Correction with Binomial Bosonic Codes
                      二项式玻色子码用于实验量子错误纠正      
Quantum error correction (QEC) is necessary for a practical quantum computer because of the inevitable coupling of quantum systems with the uncontrolled environment. A measurement-based QEC requires rapid extraction of error syndromes without disturbing the stored information and fast real-time feedback control for error corrections. Encoding quantum information on photonic states in a microwave cavity for QEC has attracted a lot of interests because of its hardware efficiency. This scheme benefits from the infinite
dimensional Hilbert space of a hARMonic oscillator for redundant information encoding and only one error syndrome that needs to be monitored. In this talk, I will describe our experimental realization of both repetitive QEC with a binomial bosonic code in a circuit quantum electrodynamics architecture and full control on the logical qubit. The demonstrated binomial bosonic codes promise the realization of QEC-enhanced precision measurements and could also be further explored for fault-tolerant quantum computation. The quantum feedback control technique developed for this work also provides new
perspectives for control and measurement of open quantum systems. 因为量子系统与非控的环境的不可避免的耦合，量子纠错（QEC）对于一台实际的量子计算机是必要的。一种测量基础的QEC需要迅速提取错误症状而不干扰存储的信息并尽快实时反馈控制给纠错。编码量子信息为光子态在一个微波洞穴给QEC由于它的硬件的效率吸引了很多兴趣。这种方案获益于给冗余信息编码的一个和谐振荡器的无限维度的希尔伯特空间，并且仅仅监控一种错误的典型表现即可。讨论中将描述我们的实验性实现，用一个二项式玻色子码重复的QEC，在一个回路量子电动力学结构和逻辑奎比特全控制两者中。演示的二项式波色子码保证实现了QEC-增强的准确测量，并且还会进一步探索容错量子计算。这项工作开发的量子反馈控制技巧还为开放量子系统的控制和测量提供了新的观点。  
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Topologically Protected Quantum Computation Based on Majorana Zero Modes: A theory Perspective   
        基于马约拉纳零模式的拓扑量子保护计算：一点理论看法  
Topological materials provide a protection from decoherence at the hardware level by using
emergent non-Abelian anyons. The simplest non-Abelian anyon involves a defect that binds
a Majorana zero-energy mode predicted to appear quite naturally in certain superconducting
systems.I will first review recent progresses and discuss the challenges in Majorana search.
Then, I will discuss a near term question: What is the simplest way to reveal the coherent
signatures of Majorana devices and measure the qubit lifetime? To answer this question, we
propose a simple transport measurement in a Majorana Coulomb blockade device. Finally, I
will discuss a serious type of error—diabatic error—in general topological quantum
computation and Majorana qubits. Diabatic errors only vanish as a power-law function when
increasing braiding operation time. This power-law behavior can wash out the advantages of
topological quantum computation. We found a scheme to overcome this serious problem.
拓扑材料为脱散提供了一种保护，在使用突然出现的非阿贝尔任意子硬件水平上。最简单的非阿贝尔任意子包含有一个缺陷它粘接一个马约拉纳零-能量模式预期，相当自然地出现在一定的超导系统。将首先回顾近来的进展并讨论马约拉纳寻找的挑战。然后将讨论一个近似技术问题：什么是最简单的方法，展示马约拉纳器件的一致性签名并测量奎比特的寿命？要回答这个问题，在一个马约拉纳哥伦布封锁器件里提出了一个简单的传输测量。最后将讨论一种严重类型的错误-透热性错误-在一般拓扑量子计算和马约拉纳奎比特。当增加编织操作时间时，透热的错误仅仅消失为一个功率-规律函数。这种功率-规律行为可以淘汰掉拓扑量子计算的优点。我们发现了一个克服这个严重问题的方法。
                          大湾区     
                                      2020-07-15