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| Main Authors: | , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.16135 |
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| _version_ | 1866910223922364416 |
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| author | Tacca, L. Lira Fagundes, L. Marques Lillo, M. Morales Navarro, M. Machuca, I. Gómez, S. Santos, G. H. dos Cariñe, J. Saavedra, G. Gómez, E. S. Lima, G. Walborn, S. P. |
| author_facet | Tacca, L. Lira Fagundes, L. Marques Lillo, M. Morales Navarro, M. Machuca, I. Gómez, S. Santos, G. H. dos Cariñe, J. Saavedra, G. Gómez, E. S. Lima, G. Walborn, S. P. |
| contents | Inter-core skew (ICS), the differential group delay between cores of a multicore fiber (MCF), is a critical parameter for both classical space-division multiplexed communications and quantum photonic networks. We present a high-precision measurement of ICS in a commercially available four-core fiber using two-photon Hong--Ou--Mandel (HOM) interference in a fiber-integrated $4\times4$ multiport beam splitter. By extracting the center position of HOM interference dips and peaks across all twelve core-pair combinations, we obtain individual ICS values with a demonstrated precision of $\pm0.11\,$ps, limited by the delay-stage positioning uncertainty. The root-mean-square ICS grows as $σ_τ(L) = κ\sqrt{L}+c$ with $κ= 48.7 \pm 2.5\,\mathrm{ps}/\!\sqrt{\mathrm{km}}$ and $c = 9.76 \pm 1.2\,$ps, over fiber lengths from $7.7\,$m to $1300\,$m. This first direct validation of the stochastic random-walk scaling across a length range spanning laboratory to field-deployed scales was made possible by HOM's immunity to first-order path fluctuations, which renders classical interferometric methods impractical for long installed fibers. The demonstrated $\pm0.11\,$ps precision represents a $\sim\!180$-fold improvement over correlation optical time-domain reflectometry (C-OTDR), the standard method for long-fiber ICS characterization. Fisher information analysis establishes a fundamental Cramér--Rao precision limit in the femtosecond range, indicating further improvement is achievable with better delay control. These results establish a practical platform for characterising timing uniformity in MCF-based networks for both quantum and classical space-division multiplexed applications. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_16135 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Sub-picosecond inter-core skew characterization in multicore fibers via Hong--Ou--Mandel interference Tacca, L. Lira Fagundes, L. Marques Lillo, M. Morales Navarro, M. Machuca, I. Gómez, S. Santos, G. H. dos Cariñe, J. Saavedra, G. Gómez, E. S. Lima, G. Walborn, S. P. Quantum Physics Optics Inter-core skew (ICS), the differential group delay between cores of a multicore fiber (MCF), is a critical parameter for both classical space-division multiplexed communications and quantum photonic networks. We present a high-precision measurement of ICS in a commercially available four-core fiber using two-photon Hong--Ou--Mandel (HOM) interference in a fiber-integrated $4\times4$ multiport beam splitter. By extracting the center position of HOM interference dips and peaks across all twelve core-pair combinations, we obtain individual ICS values with a demonstrated precision of $\pm0.11\,$ps, limited by the delay-stage positioning uncertainty. The root-mean-square ICS grows as $σ_τ(L) = κ\sqrt{L}+c$ with $κ= 48.7 \pm 2.5\,\mathrm{ps}/\!\sqrt{\mathrm{km}}$ and $c = 9.76 \pm 1.2\,$ps, over fiber lengths from $7.7\,$m to $1300\,$m. This first direct validation of the stochastic random-walk scaling across a length range spanning laboratory to field-deployed scales was made possible by HOM's immunity to first-order path fluctuations, which renders classical interferometric methods impractical for long installed fibers. The demonstrated $\pm0.11\,$ps precision represents a $\sim\!180$-fold improvement over correlation optical time-domain reflectometry (C-OTDR), the standard method for long-fiber ICS characterization. Fisher information analysis establishes a fundamental Cramér--Rao precision limit in the femtosecond range, indicating further improvement is achievable with better delay control. These results establish a practical platform for characterising timing uniformity in MCF-based networks for both quantum and classical space-division multiplexed applications. |
| title | Sub-picosecond inter-core skew characterization in multicore fibers via Hong--Ou--Mandel interference |
| topic | Quantum Physics Optics |
| url | https://arxiv.org/abs/2605.16135 |