Quantum key distribution in long distance fiber
(2021) PHYM01 20212Atomic Physics
- Abstract
- Quantum communication has been widely used as an important component in many applications of quantum information science. It is naturally utilised in the fields of quantum optics and photonics. Quantum communication and quantum cryptography have been studied as a popular subject in research for many years. However, most of the quantum-communication devices are oversized and non-portable. This problem can be easily solved by minimizing the system on a chip and using an appropriate coding method. In this thesis, a Silica Encryption Chip is used to perform quantum key distribution in long-distance fiber experiments.
In this thesis, a phase coding method is described which is used in long-distance fiber quantum cryptography. A vital component... (More) - Quantum communication has been widely used as an important component in many applications of quantum information science. It is naturally utilised in the fields of quantum optics and photonics. Quantum communication and quantum cryptography have been studied as a popular subject in research for many years. However, most of the quantum-communication devices are oversized and non-portable. This problem can be easily solved by minimizing the system on a chip and using an appropriate coding method. In this thesis, a Silica Encryption Chip is used to perform quantum key distribution in long-distance fiber experiments.
In this thesis, a phase coding method is described which is used in long-distance fiber quantum cryptography. A vital component of the device is a silica-on-silicon cryptography chip, which is used to investigate a lab-made phase coding quantum key distribution (QKD) system. The integrated optics technology on the chip is tested in experiments to verify long-distance QKD. Two fibers, 32km and 45km in length respectively, were tested individually through QKD for long-distance fiber experiments. Results showed that the quantum bit error rate (QBER) in both cases (32km and 45km) is around 10\%, which is relatively acceptable for a long-distance fiber QKD experiment. The QKD experiment demonstrates that the phase coding method with the lab-made silica-on-silicon cryptography chip has a high potential for future applications in long-distance communication. (Less) - Popular Abstract
- Existing secure quantum communication devices are very bulky. One approach to overcome this challenge is to perform quantum encryption on a chip based device. This makes quantum communication secure and portable. In this thesis, a silica encryption chip was designed and successfully used in a long-distance fiber quantum key distribution experiment. This successful experimental study is an important step for establishing the silica encryption chip for secure communication.
Quantum cryptography communication can be nicely illustrated by three hypothetical persons, i.e. a message sender (Alice), a message receiver (Bob) and a message eavesdropper (Eva). Alice needs to exchange secret messages with Bob using a kind of medium. Meanwhile Eva... (More) - Existing secure quantum communication devices are very bulky. One approach to overcome this challenge is to perform quantum encryption on a chip based device. This makes quantum communication secure and portable. In this thesis, a silica encryption chip was designed and successfully used in a long-distance fiber quantum key distribution experiment. This successful experimental study is an important step for establishing the silica encryption chip for secure communication.
Quantum cryptography communication can be nicely illustrated by three hypothetical persons, i.e. a message sender (Alice), a message receiver (Bob) and a message eavesdropper (Eva). Alice needs to exchange secret messages with Bob using a kind of medium. Meanwhile Eva has strong interest to intercept the messages exchanged in this communication medium. To prevent this, Alice and Bob decide to use a technology that recognizes, if Eva intercepts their secret message. Quantum cryptography in optical fibers is an example for such technology. If a message is intercepted by Eva, the message’s quantum state collapses and disappears. Even if Eva reproduces the same quantum state message and sends it to Bob, the underlying quantum cryptography protocol used by Alice and Bob will result in an increased error rate of the received messages, which tells Bob that the messages have been intercepted and eavesdropped.
The silica encryption chip is used to encrypt messages by means of the special quantum cryptography protocol. Encrypted messages are sent in a long-distance fiber, which is the quantum communication medium in our case. But before the silica encryption chip could be used in long-distance communication, a lot of issues needed to be solved during the project.
Alice used a laser source to produce signals that carried the security message. The original signal, however, is not suitable for silica encryption chip due to the precise layout and production process of the chip. Among other issues, the signal was not good enough to be detected by the message receiver, after travelling in the long distance fiber.
However, during the course of the project, the issues were solved one-by-one. Managing to keep the laser bandwidth sufficiently narrow, finally enabled to use the silica encryption chip to encrypt and sent messages over about 45 km distance in an optical fiber. (Less)
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http://lup.lub.lu.se/student-papers/record/9066381
@misc{9066381,
abstract = {{Quantum communication has been widely used as an important component in many applications of quantum information science. It is naturally utilised in the fields of quantum optics and photonics. Quantum communication and quantum cryptography have been studied as a popular subject in research for many years. However, most of the quantum-communication devices are oversized and non-portable. This problem can be easily solved by minimizing the system on a chip and using an appropriate coding method. In this thesis, a Silica Encryption Chip is used to perform quantum key distribution in long-distance fiber experiments.
In this thesis, a phase coding method is described which is used in long-distance fiber quantum cryptography. A vital component of the device is a silica-on-silicon cryptography chip, which is used to investigate a lab-made phase coding quantum key distribution (QKD) system. The integrated optics technology on the chip is tested in experiments to verify long-distance QKD. Two fibers, 32km and 45km in length respectively, were tested individually through QKD for long-distance fiber experiments. Results showed that the quantum bit error rate (QBER) in both cases (32km and 45km) is around 10\%, which is relatively acceptable for a long-distance fiber QKD experiment. The QKD experiment demonstrates that the phase coding method with the lab-made silica-on-silicon cryptography chip has a high potential for future applications in long-distance communication.}},
author = {{Wang, Zan}},
language = {{eng}},
note = {{Student Paper}},
title = {{Quantum key distribution in long distance fiber}},
year = {{2021}},
}