Where to Decide: Control-Plane Geometry in Coherence-Limited Quantum Networks
Abstract
Quantum networks are usually framed by two hardware limits: how fast entanglement can be heralded, and how long a memory can hold it. We establish a third, geometric limit: entanglement decoheres while control information travels, so the distance to whoever allocates resources enters the fidelity budget directly. We develop a functional-graph abstraction weighting each link by its predicted multiplicative contribution to end-to-end fidelity, separating global but delayed state from local and immediate state, and compare centralized against local allocation in a replicated discrete-event model. Centralized delivery latency grows with network diameter while local latency is nearly scale invariant, differing up to twenty-fold for short-range traffic; the coherence threshold at which a global view outweighs a fresh one does not shift across the tested sizes; and as heralding accelerates, the dominant cost moves into the control plane. Slot synchronization instead obeys the product of slot rate and one-way link delay, so it is bounded by repeater spacing rather than diameter. Controller placement, decision locality, repeater spacing and slot rate are physical design parameters, not implementation details.
Related
- Coherence transfer in quantum networks
- Induced Coherence in Quantum and Classical Interferometry: Origin and Control
- Quantum coherence as randomness under classical control
- Priority-Aware Routing for Quantum Networks:Integrating Coherence-Time Constraints into Scheduling
- Coherence-assisted quantum state preparation and thermal control through repeated interactions
BibTeX
@misc{dey2026where,
title = {{Where to Decide: Control-Plane Geometry in Coherence-Limited Quantum Networks}},
author = {I. Dey and N. Marchetti},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.23047},
eprint = {2609.23047},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.23047},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Where to Decide: Control-Plane Geometry in Coherence-Limited Quantum Networks
AU - I. Dey
AU - N. Marchetti
PY - 2026
DA - 2026/09/19
PB - arXiv
DO - 10.48550/arxiv.2609.23047
UR - https://arxiv.org/abs/2609.23047
AB - Quantum networks are usually framed by two hardware limits: how fast entanglement can be heralded, and how long a memory can hold it. We establish a third, geometric limit: entanglement decoheres while control information travels, so the distance to whoever allocates resources enters the fidelity budget directly. We develop a functional-graph abstraction weighting each link by its predicted multiplicative contribution to end-to-end fidelity, separating global but delayed state from local and immediate state, and compare centralized against local allocation in a replicated discrete-event model. Centralized delivery latency grows with network diameter while local latency is nearly scale invariant, differing up to twenty-fold for short-range traffic; the coherence threshold at which a global view outweighs a fresh one does not shift across the tested sizes; and as heralding accelerates, the dominant cost moves into the control plane. Slot synchronization instead obeys the product of slot rate and one-way link delay, so it is bounded by repeater spacing rather than diameter. Controller placement, decision locality, repeater spacing and slot rate are physical design parameters, not implementation details.
ER -