Quantum networks (QNs) enable the transfer of qubits between distant nodes using quantum teleportation, which reproduces a qubit state at a remote location by consuming a shared Bell pair. After teleportation, qubits are stored in quantum memories, where decoherence progressively degrades their quantum states. This degradation is quantified by the fidelity, defined as the overlap between the stored quantum state and the ideal target state. Some quantum applications (QApps) require the teleportation of multiple qubits and can only operate if all teleported qubits simultaneously maintain a fidelity above a given threshold. In this paper, we study how many qubits can be teleported under such fidelity-constrained operation in a two-node QN. To that end, we define a QApp-level reliability metric as the probability that all end-to-end Bell pairs satisfy the target fidelity upon completion of the multi-qubit teleportation stage. We design a Monte Carlo-based simulator that captures stochastic Bell-pair generation, Quantum Repeater (QR)-assisted entanglement distribution, and fidelity degradation. Fiber-based and terrestrial free-space optical (FSO) quantum links and representative NV-center- and trapped-ion-based quantum memories are considered. Results show that memory coherence is the main scalability bottleneck under stringent fidelity targets, while parallel entanglement generation is essential for multi-qubit teleportation.

翻译：量子网络（QN）利用量子隐形传态实现量子比特在远程节点间的转移，该过程通过消耗共享贝尔对在远程位置重建量子态。量子比特经隐形传态后存储于量子存储器中，退相干效应会逐渐降低其量子态质量。这种退化程度由保真度量化，定义为存储量子态与理想目标态之间的重叠。部分量子应用（QApp）需要传输多个量子比特，且仅当所有传输的量子比特同时保持高于给定阈值的保真度时才能运行。本文研究在如此保真度约束条件下，双节点QN中最多可传输的量子比特数量。为此，我们定义了一个QApp级可靠性指标，表征多量子比特传输阶段完成后，所有端到端贝尔对同时满足目标保真度的概率。我们设计了基于蒙特卡洛的仿真器，捕捉随机贝尔对生成、量子中继器辅助纠缠分发及保真度退化过程。研究中考虑了光纤基、地表自由空间光量子链路，以及代表性NV色心基与离子阱基量子存储器。结果表明，在严格保真度目标下，存储器相干性是可扩展性的主要瓶颈，而并行纠缠生成对多量子比特传输至关重要。