ModEn-Hub: Scalable Entanglement Architecture

Updated 2 January 2026

ModEn-Hub is a centralized quantum networking framework that distributes, manages, and orchestrates entanglement resources across multiple processing units.
It employs a hub-and-spoke design to reduce hardware scaling from O(N²) to O(N), enabling efficient all-to-all logical entanglement routing.
The architecture integrates classical control, dynamic scheduling, and caching strategies to sustain high teleportation success rates and low latency.

A Modular Entanglement Hub (ModEn-Hub) is a centralized architectural framework for distributing, orchestrating, and managing entanglement resources across multiple quantum processing modules. ModEn-Hub designs decouple quantum-optical resource generation from the classical control and scheduling needed to sustain high-fidelity, scalable quantum computation and networking. By centralizing entanglement generation, memory, and routing—while leveraging advanced scheduling and parallelism—ModEn-Hub architectures overcome the combinatorial complexity and inefficiencies of all-to-all point-to-point linking, and enable low-latency, scalable entanglement delivery for heterogeneous quantum systems (Chen et al., 31 Dec 2025).

1. Architectural Principles and ModEn-Hub Topology

A prototypical ModEn-Hub realizes a hub-and-spoke photonic interconnect. Each of $N$ peripheral quantum processing units (QPUs) connects via a single optical fiber to a central hub. The core resources within the hub are:

An entanglement generation module (EGM) equipped with tunable, high-rate Bell pair sources and a universal optical switching fabric.
A shared quantum memory cache capable of storing at least one entangled bit (ebit) per unordered node-pair.

This structure reduces the hardware scaling from $\mathcal{O}(N^2)$ for direct links to $\mathcal{O}(N)$ hub links, while still allowing dynamically reconfigurable all-to-all logical entanglement. The hub's architecture supports both point-to-point Bell pair delivery and the on-demand distribution of multipartite resource states. The classical control plane—logically decoupled from the quantum data plane—routes herald signals, orchestrates teleportation-based gate scheduling, and manages ebit caching (Chen et al., 31 Dec 2025, Chen et al., 2024).

Schematic Representation:

QPU₁    QPU₂     ...   QPU_N
  \      |             /
     [Entanglement Hub]
         |___________|

Within the hub:

Fiber input $i$ from QPU $_i$ enters the EGM switch,
Shared quantum memory sits between switch ports,
All switching and memories are orchestrated centrally.

2. Control, Scheduling, and Adaptive Orchestration

The classical control plane is responsible for resource scheduling, parallelizing entanglement attempts, and maintaining a dynamic cache of ebits. When a non-local operation (e.g., a teleportation-based controlled-NOT) is requested between a source QPU $s$ and destination QPU $d$ , the orchestrator proceeds as follows:

Checks if a ready ebit for the pair $(s,d)$ is in cache.
If not present, launches up to $K(N) = \max\{2,\lceil\kappa\log_2 N\rceil\}$ parallel entanglement attempts across that link, with $\kappa \approx 0.9$ .
Upon at least one success, one ebit is transferred for teleportation, and any surplus success is stored as a cache hit for subsequent requests.
If all parallel attempts fail, repeats up to a (typically tight) round budget $R$ (e.g., $R=3$ ).

This orchestration enables the system to sustain near-constant high teleportation success probability, even under increasing network size or loss, at the expense of increased entanglement generation attempts and resource usage (Chen et al., 31 Dec 2025).

Performance Summary:

N (QPUs)	ModEn-Hub Success (%)	Baseline Success (%)	ModEn-Hub Attempts	Baseline Attempts
1	99	99	2.0	1.5
32	90	50	10.0	2.8
128	88	30	12.0	3.0

The ModEn-Hub achieves $\sim90\%$ sustained teleportation success, while a sequential baseline degrades towards $30\%$ . Average attempt count grows logarithmically with $N$ , reflecting parallel overhead and caching benefits (Chen et al., 31 Dec 2025).

3. Entanglement Resource Management and Multiparty States

ModEn-Hubs support efficient LOCC protocols for allocating generalized $N$ -qubit multipartite entanglement—such as $W$ and GHZ states—across connected end-nodes. The hub preshares individual Bell states with each external node, then applies a global $N$ -qubit unitary, followed by measurement and minimal classical communication:

GHZ state distribution: Requires $N$ bits of classical communication and $N$ hub-memory qubits. The protocol is optimal in both communication and memory, exceeding conventional teleportation efficiency by up to $2\times$ (Chen et al., 2024).
$W$ state distribution: Requires $2N-2$ bits of classical communication, but only $N$ memory qubits at the hub; proven optimal in this architecture.

These scalable protocols allow the ModEn-Hub to compose multipartite resources for advanced networking and distributed computing with minimal resource overhead, further enabling hierarchical or nested hub topologies for global quantum networking (Chen et al., 2024, 1711.02606).

4. Resource Scaling, Performance, and Trade-Offs

ModEn-Hub orchestration introduces explicit trade-offs between entanglement bandwidth and hardware/resource cost:

Hardware scaling: Centralization reduces link count dramatically ( $N$ vs $N^2$ ). Dedicated entanglement sources and memory per hub are amortized over all pairs, reducing per-link hardware requirements.
Temporal scaling: Parallelization and caching permit success probabilities that remain approximately flat as $N$ grows, as opposed to sequential baselines limited by $O(1/N)$ scaling.
Resource cost: The approach incurs a logarithmic increase in concurrent entanglement attempts (from a baseline of $\sim3$ to $\sim10-12$ for $N=128$ ). Caching amortizes this overhead with frequent reuse.
Latency: Tight round budgets ( $R=3$ ) and centralized control support quantum operations within sub-100 μs windows, compatible with current qubit coherence times (Chen et al., 31 Dec 2025).

Scaling Law Summary:

Baseline: ${p_{\rm succ} \rightarrow 30\%}$ , $\mathbb{E}[\text{attempts}]\approx3$ as $N\gg1$ .
ModEn-Hub: ${p_{\rm succ}\approx90\%}$ flat, $\mathbb{E}[\text{attempts}]\sim O(\log N)$ (Chen et al., 31 Dec 2025).

5. Physical Realizations and Experimental Metrics

Several experimental and theoretical instantiations of ModEn-Hub architectures span photonic, superconducting, and hybrid systems:

Photonic integrated circuits: Reconfigurable Mach–Zehnder meshes in SiN (CMOS-compatible) offer programmable $N\times N$ optical transformation, supporting sub-microsecond all-pairs switching and Bell-state fidelities $\geq 0.991$ (Dong et al., 2022).
Centralized atomic or solid-state modules: Multi-user quantum memories, coupled via programmable optical/electrical buses, offer direct realization of multipartite state fusion and on-demand entanglement routing (Shi et al., 23 Apr 2025).
Superconducting transmons: Plug-and-play modular networks with detachable high-Q buses achieve $>99\%$ inter-module SWAP and Bell fidelities, supporting distributed logical qubits with fault-tolerance threshold error rates ( $\sim1\%$ ) for practical scale-up (Mollenhauer et al., 2024).
Classical control and scheduling: NUM-based rate control protocols enforce fairness and resource efficiency in multi-user hub operation, guaranteeing convergence to optimal rate allocations in time-slotted or asynchronous operation modes (Gauthier et al., 2023).

6. Optimization Strategies and Future Extensions

Enhancing ModEn-Hub throughput and reliability relies on both physical-layer improvements and algorithmic innovations:

Photonic source rates and memory coherence: Direct enhancements in entanglement generation and storage lifetimes extend operational envelopes and enable deeper parallelism (Chen et al., 31 Dec 2025).
RL-based scheduling and smart cache eviction: Machine-learning-driven orchestration can dynamically prioritize high-probability or reused links, further amortizing parallelism overhead.
Heterogeneous integration: ModEn-Hub architecture accommodates disparate QPU technologies and link types, simplifying incorporation of new hardware modules and dynamic re-routing under degradation or changing network conditions (Gualdi et al., 2010, Chen et al., 31 Dec 2025).
Hierarchical and interconnected hubs: Local ModEn-Hubs can be composed into higher-level logical networks, supporting arbitrarily large and flexible distributed computing or communication systems (1711.02606, Chen et al., 2024).

The decoupling of quantum entanglement generation from classical orchestration stands as a defining feature of ModEn-Hub architectures, enabling scalable, flexible, and hardware-efficient quantum network and computing operations across a broad range of platforms (Chen et al., 31 Dec 2025).