三维散射中的概率流龙卷风环

Sagnac环上相长干涉实现单光子频率转换和多模纠缠

Single-photon frequency conversion and multi-mode entanglement via constructive interference on Sagnac Loop

基于Sagnac波导环中的相长干涉，提出了一种利用输入输出理论实现选择性频率变换和多频模W纠缠的有效方案。我们可以通过选择适当的参数值来调整输出光子的概率幅度。可调的几率振幅将导致产生具有可选择频率的输出光子，并在较宽的参数值范围内产生不同频率模式的W光子纠缠。计算结果表明，该方案对参数偏差和自发衰变具有较强的鲁棒性。

量子粒子在与导线耦合的环中的逃逸行为

Escape behaviour of a quantum particle in a loop coupled to a lead

我们考虑一个由恒定磁通量$Φ$穿过的圆周$L$的一维回路，并连接到具有耦合参数$ε$的无限长导线。假设粒子的初态$ψ_0$被限制在环内并自由演化，我们分析了粒子的非逃逸概率$P(ψ_0,L,Φ,ε,t)$随时间的演化，它是粒子在以后某个时刻仍在环内的概率$t$ .

Quasi-probability distributions in Loop Quantum Cosmology

In this paper, we introduce a complete family of parametrized quasi-probability distributions in phase space and their corresponding Weyl quantization maps with the aim to generalize the recently developed Wigner-Weyl formalism within the Loop Quantum Cosmology program (LQC). In particular, we intend to define those quasi-distributions for states valued on the Bohr compactification of the real line in such a way that they are labeled by a parameter that accounts for the ordering ambiguity corresponding to non-commutative quantum operators. Hence, we notice that the projections of the parametri…

Grover Search with Lackadaisical Quantum Walks

The lazy random walk, where the walker has some probability of staying put, is a useful tool in classical algorithms. We propose a quantum analogue, the lackadaisical quantum walk, where each vertex is given $l$ self-loops, and we investigate its effects on Grover's algorithm when formulated as search for a marked vertex on the complete graph of $N$ vertices. For the discrete-time quantum walk using the phase flip coin, adding a self-loop to each vertex boosts the success probability from 1/2 to 1. Additional self-loops, however, decrease the success probability. Using instead the Ambainis, Ke…

Adaptive loop-based subtraction of a single photon from a traveling beam of light

Manipulating light by adding and subtracting individual photons is a powerful approach with a principal drawback: the operations are fundamentally probabilistic and the probability is often small. This limits not only the fundamental scalability but also the number of operations that can be applied in realistic experimental settings. We propose and analyze an adaptive technique which can significantly increase the probability of success while preserving the quality of the photon subtraction. We show the improvement both in single mode preparation and manipulation of non-Gaussian states with ne…

时间环路复用：一种有效利用资源的光子对源复用方案

Temporal Loop Multiplexing: A resource efficient scheme for multiplexed photon-pair sources

单光子是光子量子信息处理的重要资源。然而，即使是基于光子对产生和预示检测的最先进的单光子源，在请求单光子时也仅具有低概率递送单光子。我们分析了一个方案，使用开关光纤延迟环，以增加交付概率每个时间仓的单光子从预示源。我们表明，对于现实的实验参数，结合多达15个脉冲的输出可以产生10倍的性能改善。我们考虑了该计划的未来性能以及可能的组件改进。