Quantum communication on the bosonic loss-dephasing channel
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arXiv
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| Autores principales: | , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866909267886342144 |
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| author | Mele, Francesco Anna Salek, Farzin Giovannetti, Vittorio Lami, Ludovico |
| author_facet | Mele, Francesco Anna Salek, Farzin Giovannetti, Vittorio Lami, Ludovico |
| contents | Quantum optical systems are typically affected by two types of noise: photon loss and dephasing. Despite extensive research on each noise process individually, a comprehensive understanding of their combined effect is still lacking. A crucial problem lies in determining the values of loss and dephasing for which the resulting loss-dephasing channel is anti-degradable, implying the absence of codes capable of correcting its effect or, alternatively, capable of enabling quantum communication. A conjecture in [Quantum 6, 821 (2022)] suggested that the bosonic loss-dephasing channel is anti-degradable if and only if the loss is above $50\%$. In this paper we refute this conjecture, specifically proving that for any value of the loss, if the dephasing is above a critical value, then the bosonic loss-dephasing channel is anti-degradable. While our result identifies a large parameter region where quantum communication is not possible, we also prove that if two-way classical communication is available, then quantum communication -- and thus quantum key distribution -- is always achievable, even for high values of loss and dephasing. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_15634 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Quantum communication on the bosonic loss-dephasing channel Mele, Francesco Anna Salek, Farzin Giovannetti, Vittorio Lami, Ludovico Quantum Physics Quantum optical systems are typically affected by two types of noise: photon loss and dephasing. Despite extensive research on each noise process individually, a comprehensive understanding of their combined effect is still lacking. A crucial problem lies in determining the values of loss and dephasing for which the resulting loss-dephasing channel is anti-degradable, implying the absence of codes capable of correcting its effect or, alternatively, capable of enabling quantum communication. A conjecture in [Quantum 6, 821 (2022)] suggested that the bosonic loss-dephasing channel is anti-degradable if and only if the loss is above $50\%$. In this paper we refute this conjecture, specifically proving that for any value of the loss, if the dephasing is above a critical value, then the bosonic loss-dephasing channel is anti-degradable. While our result identifies a large parameter region where quantum communication is not possible, we also prove that if two-way classical communication is available, then quantum communication -- and thus quantum key distribution -- is always achievable, even for high values of loss and dephasing. |
| title | Quantum communication on the bosonic loss-dephasing channel |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2401.15634 |