Qubit-loss-free fusion of W states
Qubit-loss-free fusion of W states
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DOI：
10.1103/physreva.94.062315
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发表时间：
2016-12
影响因子：
2.9
通讯作者：
K. Li;Fan-Zhen Kong;Ming Yang;Qing Yang;Z. Cao
中科院分区：
文献类型：
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作者：
K. Li;Fan-Zhen Kong;Ming Yang;Qing Yang;Z. Cao
融合技术在大规模粒子的制备中起着关键作用，但现有的融合方案存在量子比特丢失问题，即输出纠缠量子比特的个数小于输入纠缠量子比特的个数之和，这必然会降低融合效率、增加融合步数以及对量子存储的要求。在本文中，我们设计了一种融合机制，将两个小星体融合成一个大尺度的星体，而不会丢失量子比特，因此我们称之为量子比特无损失(QLF)融合机制。这种QLF融合机制基于从两个小粒子中提取的两个量子比特的双结果正算符测量，既适用于纯态，也适用于混合态。这种融合机制的QLF性质明显增加了最终得到的态的大小，并大大减少了融合步骤的数量以及达到目标大小稳定所需的量子存储器，因此它比现有的融合方案更有效和可行。在我们的QLF融合方案中没有完全的失败输出，并且所有的垃圾状态都是可回收的。提出了在腔量子电动力学系统和三量子比特HeisenbergXYZ模型中实现这种QLF融合机制的两个例子方案，论证了这种QLF融合机制的物理实现的可能性。
Fusion technique plays a key role in the preparation of large-scalestates, but the currently existing fusion schemes are suffering from the qubit loss problem, i.e., the number of the output entangled qubits is smaller than the sum of numbers of the input entangled qubits, which will inevitably decrease the fusion efficiency and increase the number of fusion steps as well as the requirement of quantum memories. In this paper, we design a fusion mechanism to fuse two small-sizestates into a large-scalestate without qubit loss, and thus we call it qubit-loss-free (QLF) fusion mechanism. This QLF fusion mechanism is based on a two-outcome positive-operator valued measurement on two qubits extracting from two small-sizestates, and works for both pure and mixedstates. The QLF nature of this fusion mechanism clearly increases the final size of the obtainedstate, and greatly reduces the number of fusion steps as well as the requirement of quantum memories required to achieve astate of a target size, so it is more efficient and feasible than the currently existing fusion schemes. There is no complete failure output in our QLF fusion scheme, and all the garbage states are recyclable. Two example schemes are proposed to realize this QLF fusion mechanism in a cavity quantum electrodynamics system and three-qubit HeisenbergXYZmodel, respectively, which demonstrates the possibility of the physical realization of this QLF fusion mechanism.