How Many Qubits Can Be Teleported? Scalability of Fidelity-Constrained Quantum Applications

2026-03-30

AI Summary

This work investigates the scalability of multi-qubit transmission in a two-node quantum network under fidelity constraints, where the number of simultaneously transmissible qubits is fundamentally limited by quantum memory decoherence and entanglement distribution efficiency. The study introduces a novel approach to quantify the scalability limit by integrating application-level fidelity requirements with end-to-end Bell pair reliability for the first time. A Monte Carlo simulator is developed, incorporating realistic models of fiber and free-space links, NV-center and ion-trap quantum memories, and quantum repeater protocols, enabling systematic evaluation of key system parameters. Results demonstrate that memory coherence time constitutes the primary bottleneck for high-fidelity multi-qubit transmission, while parallel entanglement generation plays a critical role in enhancing network scalability.

Technology Category

• Machine Learning: Quantum Machine Learning
• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Search and Optimization: Distributed Search

Application Category

• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

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.

Problem

• quantum teleportation
• fidelity
• quantum networks
• quantum memories
• scalability

Innovation

• fidelity-constrained teleportation
• multi-qubit scalability
• quantum network reliability
• Monte Carlo simulation
• quantum memory coherence