Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack
Abstract The twin-field class quantum key distribution (TF-class QKD) has experimentally demonstrated the ability to surpass the fundamental rate-distance limit without requiring a quantum repeater, as a revolutional milestone. In TF-class QKD implementation, an optical phase-locked loop (OPLL) stru...
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2025-01-01
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| Series: | npj Quantum Information |
| Online Access: | https://doi.org/10.1038/s41534-025-00963-9 |
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| author | Qingquan Peng Jiu-Peng Chen Tianyi Xing Dongyang Wang Yizhi Wang Yang Liu Anqi Huang |
| author_facet | Qingquan Peng Jiu-Peng Chen Tianyi Xing Dongyang Wang Yizhi Wang Yang Liu Anqi Huang |
| author_sort | Qingquan Peng |
| collection | DOAJ |
| description | Abstract The twin-field class quantum key distribution (TF-class QKD) has experimentally demonstrated the ability to surpass the fundamental rate-distance limit without requiring a quantum repeater, as a revolutional milestone. In TF-class QKD implementation, an optical phase-locked loop (OPLL) structure is commonly employed to generate a reference light with correlated phase, ensuring coherence of optical fields between Alice and Bob. In this configuration, the reference light, typically located in the untrusted station Charlie, solely provides wavelength reference for OPLL and does not participate in quantum-state encoding. However, the reference light may open a door for Eve to enter the source stations that are supposed to be well protected. Here, by identifying vulnerabilities of an acousto-optic modulator (AOM) in the OPLL scheme, we propose and demonstrate a wavelength-switching attack on a TF-class QKD system. This attack involves Eve deliberately manipulating the wavelength of the reference light to increase mean photon number of prepared quantum states, while maintaining stable interference between Alice and Bob as required by TF-class QKD protocols. The maximum observed increase in mean photon number is 8.7%, which has been theoretically proven to compromise the security of a TF-class QKD system. Moreover, we have shown that with well calibration of the modulators, the attack can be eliminated. Through this study, we highlight the importance of system calibration in the practical security in TF-class QKD implementation. |
| format | Article |
| id | doaj-art-46ef4139f4ff426b9835360cc977959d |
| institution | Kabale University |
| issn | 2056-6387 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Quantum Information |
| spelling | doaj-art-46ef4139f4ff426b9835360cc977959d2025-01-19T12:34:13ZengNature Portfolionpj Quantum Information2056-63872025-01-0111111010.1038/s41534-025-00963-9Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attackQingquan Peng0Jiu-Peng Chen1Tianyi Xing2Dongyang Wang3Yizhi Wang4Yang Liu5Anqi Huang6Institute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer Science and Technology, National University of Defense TechnologyJinan Institute of Quantum Technology and Hefei National Laboratory Jinan BranchInstitute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer Science and Technology, National University of Defense TechnologyInstitute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer Science and Technology, National University of Defense TechnologyInstitute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer Science and Technology, National University of Defense TechnologyJinan Institute of Quantum Technology and Hefei National Laboratory Jinan BranchInstitute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer Science and Technology, National University of Defense TechnologyAbstract The twin-field class quantum key distribution (TF-class QKD) has experimentally demonstrated the ability to surpass the fundamental rate-distance limit without requiring a quantum repeater, as a revolutional milestone. In TF-class QKD implementation, an optical phase-locked loop (OPLL) structure is commonly employed to generate a reference light with correlated phase, ensuring coherence of optical fields between Alice and Bob. In this configuration, the reference light, typically located in the untrusted station Charlie, solely provides wavelength reference for OPLL and does not participate in quantum-state encoding. However, the reference light may open a door for Eve to enter the source stations that are supposed to be well protected. Here, by identifying vulnerabilities of an acousto-optic modulator (AOM) in the OPLL scheme, we propose and demonstrate a wavelength-switching attack on a TF-class QKD system. This attack involves Eve deliberately manipulating the wavelength of the reference light to increase mean photon number of prepared quantum states, while maintaining stable interference between Alice and Bob as required by TF-class QKD protocols. The maximum observed increase in mean photon number is 8.7%, which has been theoretically proven to compromise the security of a TF-class QKD system. Moreover, we have shown that with well calibration of the modulators, the attack can be eliminated. Through this study, we highlight the importance of system calibration in the practical security in TF-class QKD implementation.https://doi.org/10.1038/s41534-025-00963-9 |
| spellingShingle | Qingquan Peng Jiu-Peng Chen Tianyi Xing Dongyang Wang Yizhi Wang Yang Liu Anqi Huang Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack npj Quantum Information |
| title | Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack |
| title_full | Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack |
| title_fullStr | Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack |
| title_full_unstemmed | Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack |
| title_short | Practical security of twin-field quantum key distribution with optical phase-locked loop under wavelength-switching attack |
| title_sort | practical security of twin field quantum key distribution with optical phase locked loop under wavelength switching attack |
| url | https://doi.org/10.1038/s41534-025-00963-9 |
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