Secret Key Rate Limits in Coexisting Classical-Quantum Optical Links

• URL: http://arxiv.org/abs/2602.21671v1
• Date: Wed, 25 Feb 2026 08:08:52 GMT
• Title: Secret Key Rate Limits in Coexisting Classical-Quantum Optical Links
• Authors: Lucas Alves Zischler, Amirhossein Ghazisaeidi, Antonio Mecozzi, Cristian Antonelli,
• Abstract summary: We derive expressions for evaluating the accumulated interference power from coexisting classical signals in a quantum frequency channel.<n>Our model enables effective design of classical-quantum systems in single-mode fibers.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Classical-quantum coexistence enables cost-effective transmission of data and quantum signals over the same fiber-optic channel. Nevertheless, weak quantum-key distribution (QKD) signals are susceptible to non-linear interference generated from the classical traffic, primarily spontaneous Raman scattering (SpRS) and four-wave-mixing (FWM), as well as to unfiltered noise. In QKD protocols, increased channel loss and excess noise both reduce the secret key rates (SKRs), as illustrated in this work for the two-state BB84 and Gaussian-modulated coherent-states (GMCS) protocols. In this study, we derive closed-form expressions for evaluating the accumulated interference power from coexisting classical signals in a quantum frequency channel. Our model enables effective design of classical-quantum systems in single-mode fibers (SMFs), capturing the evolution of interference arising from the relevant physical phenomena. We utilize the model to examine frequency allocation in multiband transmission systems, demonstrating that, contrary to common practice of allocating QKD channels in the O-band, increased SKR is achieved by placing quantum channels in the upper E-/lower S-band across the relevant scenarios.

Related papers

• In situ quantum verification of polarization-stabilized optical channels [0.712813885457233]
  We introduce a novel in situ benchmarking approach that augments a classical polarization tracking system.<n>The method uses the reconstructed map both to validate the classical compensation and to expose noise sources it fails to capture.<n>Our results should unlock new opportunities for in situ channel characterization in quantum-classical coexistence networks.
  arXiv  Detail & Related papers  (2025-10-30T00:19:59Z)
• Accurate and Effective Model for Coexistence of Classical and Quantum Signals In Optical Fibers [5.450971469135477]
  We discuss the main interference mechanisms in coexistence scenarios and provide a model to quantify their impact on the quantum signal quality.<n>The model accounts for out-of-band non-linear interference effects, namely spontaneous Raman scattering (SpRS) and four-wave-mixing (FWM)<n>Our model reveals that FWM has negligible impact in counter-propagating schemes, but can be relevant in co-propagating schemes under certain scenarios.
  arXiv  Detail & Related papers  (2025-10-03T08:22:41Z)
• Crosstalk-Resilient Quantum MIMO for Scalable Quantum Communications [40.44880302154388]
  Crosstalk arises when physically coupled quantum modes interfere, degrading signal fidelity.<n>We propose a mitigation strategy based on encoding discrete-variable quantum information into continuous-variable modes.<n>We prove the existence of a gauge-fixing decoder enabling recovery of the logical information.
  arXiv  Detail & Related papers  (2025-06-26T18:40:26Z)
• Robustness of WDM technique for the co-propagation of quantum with classical signals in an optical fiber [1.6999370482438731]
  We study the evolution of co-propagating quantum and classical signals that are launched using WDM.<n> calculations show that only the first two nearest channels from the classical channel experience noticeable crosstalk.<n>This reflects the WDM technique is in principle robust in the integration of weak quantum links into classical data traffic.
  arXiv  Detail & Related papers  (2024-11-25T21:22:47Z)
• Mitigating Errors on Superconducting Quantum Processors through Fuzzy Clustering [38.02852247910155]
  A new Quantum Error Mitigation (QEM) technique uses Fuzzy C-Means clustering to specifically identify measurement error patterns. We report a proof-of-principle validation of the technique on a 2-qubit register, obtained as a subset of a real NISQ 5-qubit superconducting quantum processor. We demonstrate that the FCM-based QEM technique allows for reasonable improvement of the expectation values of single- and two-qubit gates based quantum circuits.
  arXiv  Detail & Related papers  (2024-02-02T14:02:45Z)
• Eavesdropper localization for quantum and classical channels via nonlinear scattering [58.720142291102135]
  Quantum key distribution (QKD) offers theoretical security based on the laws of physics. We present a novel approach to eavesdropper location that can be employed in quantum as well as classical channels. We demonstrate that our approach outperforms conventional OTDR in the task of localizing an evanescent outcoupling of 1% with cm precision inside standard optical fibers.
  arXiv  Detail & Related papers  (2023-06-25T21:06:27Z)
• Learning Distributed Quantum State Discrimination with Noisy Classical Communications [39.000858564696856]
  This paper presents Noise Aware-LOCCNet (NA-LOCCNet) for distributed quantum state discrimination in the presence of noisy communication. We propose specific ansatzes for the case of two observed qubit pairs, and we describe a noise-aware training design criterion.
  arXiv  Detail & Related papers  (2022-07-22T22:06:56Z)
• Towards fully-fledged quantum and classical communication over deployed fiber with up-conversion module [47.187609203210705]
  We propose and demonstrate a new method, based on up-conversion assisted receiver, for co-propagating classical light and QKD signals. Our proposal exhibits higher tolerance for noise in comparison to the standard receiver, thus enabling the distribution of secret keys in the condition of 4 dB-higher classical power.
  arXiv  Detail & Related papers  (2021-06-09T13:52:27Z)
• Universal non-adiabatic control of small-gap superconducting qubits [47.187609203210705]
  We introduce a superconducting composite qubit formed from two capacitively coupled transmon qubits. We control this low-frequency CQB using solely baseband pulses, non-adiabatic transitions, and coherent Landau-Zener interference. This work demonstrates that universal non-adiabatic control of low-frequency qubits is feasible using solely baseband pulses.
  arXiv  Detail & Related papers  (2020-03-29T22:48:34Z)
• Quantum emulation of coherent backscattering in a system of superconducting qubits [45.82374977939355]
  We use multi-pass Landau-Zener transitions at the avoided crossing of a highly-coherent superconducting qubit to emulate weak localization (WL) and universal conductance fluctuations (UCF) The higher coherence of this qubit enabled the realization of both effects, in contrast to earlier work arXiv:1204.6428, which successfully emulated UCF, but did not observe WL.
  arXiv  Detail & Related papers  (2019-12-28T17:11:53Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.