Title: Continuous-variable entanglement distillation over a pure loss channel with multiple quantum scissors Show Chinese title

Title: 纯损耗信道上具有多个量子剪刀的连续变量纠缠浓缩

Abstract: Entanglement distillation is a key primitive for distributing high-quality entanglement between remote locations. Probabilistic noiseless linear amplification based on the quantum scissors is a candidate for entanglement distillation from noisy continuous-variable (CV) entangled states. Being a non-Gaussian operation, quantum scissors is challenging to analyze. We present a derivation of the non-Gaussian state heralded by multiple quantum scissors in a pure loss channel with two-mode squeezed vacuum input. We choose the reverse coherent information (RCI)---a proven lower bound on the distillable entanglement of a quantum state under one-way local operations and classical communication (LOCC), as our figure of merit. We evaluate a Gaussian lower bound on the RCI of the heralded state. We show that it can exceed the unlimited two-way LOCCassisted direct transmission entanglement distillation capacity of the pure loss channel. The optimal heralded Gaussian RCI with two quantum scissors is found to be significantly more than that with a single quantum scissors, albeit at the cost of decreased success probability. Our results fortify the possibility of a quantum repeater scheme for CV quantum states using the quantum scissors. Show Chinese abstract

Abstract: 纠缠浓缩是将高质量纠缠在远程位置之间分发的关键原语。 基于量子剪刀的概率无噪声线性放大是来自噪声连续变量（CV）纠缠态的纠缠浓缩的候选方案。 作为一种非高斯操作，量子剪刀难以分析。 我们推导了在具有双模压缩真空输入的纯损耗信道中，由多个量子剪刀所预告的非高斯态。 我们选择反向相干信息（RCI）——一种在单向局部操作和经典通信（LOCC）下量子态可浓缩纠缠的已证明下限——作为我们的性能指标。 我们评估了所预告态的RCI的高斯下限。 我们表明，它能够超过纯损耗信道中无限双向LOCC辅助直接传输纠缠浓缩容量。 发现使用两个量子剪刀的最优预告高斯RCI显著高于使用单个量子剪刀的情况，尽管成功概率有所降低。 我们的结果加强了使用量子剪刀对CV量子态进行量子中继方案的可能性。