The entanglement structure between different frequency components within broadband quantum light pulses, forged at entanglement creation, represents a promising route to the practical delivery of many multipartite quantum information applications. However, the scalability of such applications is largely limited by the entanglement decoherence caused by photon loss. One promising method to combat such losses is noiseless linear amplification. However, while there have been various procedures that implement noiseless linear amplification on single-mode states, no realization has thus far been proposed for noiseless linear amplification on quantum states carrying a multimode structure. In this work we close this gap, proposing a noiseless linear amplifier (NLA) with photon catalysis (PC), namely, the PC-NLA. Constructing a multimode version of an existing NLA that uses quantum scissors (QS), the QS-NLA, we then show how the PC-NLA is compatible with the QS-NLA, even though the former uses half the physical resources of the latter. We then apply our multimode NLA frameworks to the problem of continuous-variable (CV) entanglement distillation, determining how the multimode structure of the entanglement impacts the performance of the NLAs. Different from single-mode NLA analyses, we find that a multimode NLA is only effective as a CV entanglement distillation strategy when the channel loss is beyond some threshold—a threshold largely dependent on the multimode structure. The results provided here will be valuable for real-world implementations of multipartite quantum information applications that utilize complex entanglement structure within broadband light pulses.

中文翻译：

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适用于多模态的无噪声线性放大器

宽带量子光脉冲中不同频率分量之间的纠缠结构是在纠缠创建时伪造的，它是许多多部分量子信息应用实际交付的有希望的途径。但是，此类应用程序的可伸缩性在很大程度上受到光子丢失引起的纠缠退相干的限制。解决这种损失的一种有前途的方法是无噪声线性放大。然而，尽管已经存在各种对单模态实施无噪声线性放大的方法，但是迄今为止，尚未提出针对对带有多模结构的量子态进行无噪声线性放大的实现。在这项工作中，我们缩小了这一差距，提出了一种具有光子催化（PC）的无噪声线性放大器（NLA），即PC-NLA。构建使用量子剪刀（QS）的现有NLA的多模版本QS-NLA，然后我们将展示PC-NLA如何与QS-NLA兼容，即使前者使用后者的物理资源的一半。然后，我们将多模NLA框架应用于连续变量（CV）纠缠蒸馏的问题，确定纠缠的多模结构如何影响NLA的性能。与单模NLA分析不同，我们发现，多通道NLA仅在通道损耗超出某个阈值时有效用作CV纠缠蒸馏策略，该阈值很大程度上取决于多模结构。