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arXiv · 2502.04856

Probabilistic pulse-position modulation for classical communication on quantum channels

Farzad Kianvash·Matteo Rosati
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Abstract

Classical communication over lossy quantum channels is an essential topic in quantum information theory, with practical implications for optical-fiber and free-space communications. Multi-phase Hadamard codes, based on coherent-state Binary Phase-Shift Keying (BPSK) modulation and decoded using vacuum-or-pulse (VP) detectors, offer a promising approach for achieving high communication rates while relying only on linear optics and single-photon detectors (SPDs). However, their performance does not reach the ultimate Holevo limit. In this work, we propose a generalization of Hadamard codes that distributes the signal across multiple modes with optimized probabilities, rather than concentrating it in a single mode, dubbed probabilistic pulse-position modulation (PPPM). We derive an achievable communication rate, demonstrating that our PPPM can outperform traditional Hadamard codes in certain intermediate energy regimes.

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Farzad Kianvash, Matteo Rosati. 2025-02-07. Probabilistic pulse-position modulation for classical communication on quantum channels. https://arxiv.org/abs/2502.04856

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