Tight scaling of key rate for differential-phase-shift quantum key distribution
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arXiv
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| Autori principali: | , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866910757680054272 |
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| author | Mizutani, Akihiro Tsurumaru, Toyohiro |
| author_facet | Mizutani, Akihiro Tsurumaru, Toyohiro |
| contents | The performance of quantum key distribution (QKD) protocols is evaluated based on the ease of implementation and key generation rate. Among major protocols, the differential-phase-shift (DPS) protocol has the advantage of simple implementation using a train of coherent pulses and a passive detection unit. Unfortunately, however, its key rate is known to be at least proportional to $η^2$ with respect to channel transmission $η\to0$. If one can only prove the rate proportional to $η^2$ and cannot improve the analysis beyond that, then the DPS protocol will be deemed inferior to other major protocols, such as the decoy BB84 protocol. In this paper, we consider a type of DPS protocol in which the phase of each emitted block comprising $n$ pulses is randomized and significantly improve the analysis of its key rate. Specifically, we reveal that the key rate is proportional to $η^{1+\frac{1}{n-2}}$ and this rate is tight. This implies that the DPS protocol can achieve a key rate proportional to $η$ for a large number of $n$, which is the same scaling as the decoy BB84 protocol. Our result suggests that the DPS protocol can achieve a combination of both advantages of ease of implementation and a high key generation rate. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_10033 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Tight scaling of key rate for differential-phase-shift quantum key distribution Mizutani, Akihiro Tsurumaru, Toyohiro Quantum Physics The performance of quantum key distribution (QKD) protocols is evaluated based on the ease of implementation and key generation rate. Among major protocols, the differential-phase-shift (DPS) protocol has the advantage of simple implementation using a train of coherent pulses and a passive detection unit. Unfortunately, however, its key rate is known to be at least proportional to $η^2$ with respect to channel transmission $η\to0$. If one can only prove the rate proportional to $η^2$ and cannot improve the analysis beyond that, then the DPS protocol will be deemed inferior to other major protocols, such as the decoy BB84 protocol. In this paper, we consider a type of DPS protocol in which the phase of each emitted block comprising $n$ pulses is randomized and significantly improve the analysis of its key rate. Specifically, we reveal that the key rate is proportional to $η^{1+\frac{1}{n-2}}$ and this rate is tight. This implies that the DPS protocol can achieve a key rate proportional to $η$ for a large number of $n$, which is the same scaling as the decoy BB84 protocol. Our result suggests that the DPS protocol can achieve a combination of both advantages of ease of implementation and a high key generation rate. |
| title | Tight scaling of key rate for differential-phase-shift quantum key distribution |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2405.10033 |