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25 MHz clock continuous-variable quantum key distribution system over 50 km fiber channel.

Wang C, Huang D, Huang P, Lin D, Peng J, Zeng G - Sci Rep (2015)

Bottom Line: In this paper, a practical continuous-variable quantum key distribution system is developed and it runs in the real-world conditions with 25 MHz clock rate.Practically, our system is tested for more than 12 hours with a final secret key rate of 52 kbps over 50 km transmission distance, which is the highest rate so far in such distance.Our system may pave the road for practical broadband secure quantum communication with continuous variables in the commercial conditions.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Advanced Optical Communication Systems and Networks, Shanghai Key Laboratory on Navigation and Location-based Service, and Center of Quantum Information Sensing and Processing, Shanghai Jiao Tong University, Shanghai 200240, China.

ABSTRACT
In this paper, a practical continuous-variable quantum key distribution system is developed and it runs in the real-world conditions with 25 MHz clock rate. To reach high-rate, we have employed a homodyne detector with maximal bandwidth to 300 MHz and an optimal high-efficiency error reconciliation algorithm with processing speed up to 25 Mbps. To optimize the stability of the system, several key techniques are developed, which include a novel phase compensation algorithm, a polarization feedback algorithm, and related stability method on the modulators. Practically, our system is tested for more than 12 hours with a final secret key rate of 52 kbps over 50 km transmission distance, which is the highest rate so far in such distance. Our system may pave the road for practical broadband secure quantum communication with continuous variables in the commercial conditions.

No MeSH data available.


Related in: MedlinePlus

The final secret key rate of the 25 MHz CVQKD system.The blue dash line denotes the asymptotical theoretical key rate, and the red solid line is the finite size theoretical key rate with block size of 109. The modulation variance VA = 15, quantum efficiency is 60%, reconciliation efficiency is 0.967, the excess noise is 0.07 and the frame overhead is 10%.
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f3: The final secret key rate of the 25 MHz CVQKD system.The blue dash line denotes the asymptotical theoretical key rate, and the red solid line is the finite size theoretical key rate with block size of 109. The modulation variance VA = 15, quantum efficiency is 60%, reconciliation efficiency is 0.967, the excess noise is 0.07 and the frame overhead is 10%.

Mentions: Comparing to the results in theoretical regime, i.e., the infinite data block, a realistic block length limits the secure distance and one cannot remove this uncertainties completely. This is actually the finite-size effects which are mainly associated with the excess noise and privacy amplification. By making use of the realistic experiment conditions, we compute the final secret key rates according to Eq. (1). In our system, 50% of the optical pulses were used for generating the key and the rest were used for parameter estimation and frame overhead. Under this condition, the experiment and simulation results of the secret key rates are plotted in Fig. 3. The dash line (blue) represents the asymptotic theoretical key rate, and the solid line (red) denotes the computed theoretical key rate under the finite-size with block size of 109. Theoretically, we can get a final secret key of 58.53 kbps at 50 km and 464.8 kbps at 30 km with the block size of 109. However, due to the frame overhead for synchronization and other overhead, only about 90% data of the block size may be used for the secret key distillation and parameter estimation. Accordingly, the experiment result is about 52 kbps at 50 km which is expressed using cross in Fig. 3. To compare with the previous experiments, the results presented in refs [25,28,30] are also plotted. As a remark, we note that the theoretical value under the finite-size effect with sample block of 109 is 58.53 kbps, while the experiment result is 52 kbps as mentioned above. This is due to the additional consumption which are mainly from the stability of the system, frame overhead, the precision of phase estimation and adjustment, and the interaction between Alice and Bob. These factors will be further optimized in the further investigation.


25 MHz clock continuous-variable quantum key distribution system over 50 km fiber channel.

Wang C, Huang D, Huang P, Lin D, Peng J, Zeng G - Sci Rep (2015)

The final secret key rate of the 25 MHz CVQKD system.The blue dash line denotes the asymptotical theoretical key rate, and the red solid line is the finite size theoretical key rate with block size of 109. The modulation variance VA = 15, quantum efficiency is 60%, reconciliation efficiency is 0.967, the excess noise is 0.07 and the frame overhead is 10%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588593&req=5

f3: The final secret key rate of the 25 MHz CVQKD system.The blue dash line denotes the asymptotical theoretical key rate, and the red solid line is the finite size theoretical key rate with block size of 109. The modulation variance VA = 15, quantum efficiency is 60%, reconciliation efficiency is 0.967, the excess noise is 0.07 and the frame overhead is 10%.
Mentions: Comparing to the results in theoretical regime, i.e., the infinite data block, a realistic block length limits the secure distance and one cannot remove this uncertainties completely. This is actually the finite-size effects which are mainly associated with the excess noise and privacy amplification. By making use of the realistic experiment conditions, we compute the final secret key rates according to Eq. (1). In our system, 50% of the optical pulses were used for generating the key and the rest were used for parameter estimation and frame overhead. Under this condition, the experiment and simulation results of the secret key rates are plotted in Fig. 3. The dash line (blue) represents the asymptotic theoretical key rate, and the solid line (red) denotes the computed theoretical key rate under the finite-size with block size of 109. Theoretically, we can get a final secret key of 58.53 kbps at 50 km and 464.8 kbps at 30 km with the block size of 109. However, due to the frame overhead for synchronization and other overhead, only about 90% data of the block size may be used for the secret key distillation and parameter estimation. Accordingly, the experiment result is about 52 kbps at 50 km which is expressed using cross in Fig. 3. To compare with the previous experiments, the results presented in refs [25,28,30] are also plotted. As a remark, we note that the theoretical value under the finite-size effect with sample block of 109 is 58.53 kbps, while the experiment result is 52 kbps as mentioned above. This is due to the additional consumption which are mainly from the stability of the system, frame overhead, the precision of phase estimation and adjustment, and the interaction between Alice and Bob. These factors will be further optimized in the further investigation.

Bottom Line: In this paper, a practical continuous-variable quantum key distribution system is developed and it runs in the real-world conditions with 25 MHz clock rate.Practically, our system is tested for more than 12 hours with a final secret key rate of 52 kbps over 50 km transmission distance, which is the highest rate so far in such distance.Our system may pave the road for practical broadband secure quantum communication with continuous variables in the commercial conditions.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Advanced Optical Communication Systems and Networks, Shanghai Key Laboratory on Navigation and Location-based Service, and Center of Quantum Information Sensing and Processing, Shanghai Jiao Tong University, Shanghai 200240, China.

ABSTRACT
In this paper, a practical continuous-variable quantum key distribution system is developed and it runs in the real-world conditions with 25 MHz clock rate. To reach high-rate, we have employed a homodyne detector with maximal bandwidth to 300 MHz and an optimal high-efficiency error reconciliation algorithm with processing speed up to 25 Mbps. To optimize the stability of the system, several key techniques are developed, which include a novel phase compensation algorithm, a polarization feedback algorithm, and related stability method on the modulators. Practically, our system is tested for more than 12 hours with a final secret key rate of 52 kbps over 50 km transmission distance, which is the highest rate so far in such distance. Our system may pave the road for practical broadband secure quantum communication with continuous variables in the commercial conditions.

No MeSH data available.


Related in: MedlinePlus