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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

Experimental excess noise measured over 12 hours with a SNR of 0.9 on Bob’ side.In experiment, the length of fiber is 50 km corresponding to 10 db losses, the red pulse symbols indicate the measured excess noise and worst-case estimator, the size of block is 109, which corresponding about 2.6 min of data sampling. The blue line shows the threshold of excess noise that can yield positive secret key rate.
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f4: Experimental excess noise measured over 12 hours with a SNR of 0.9 on Bob’ side.In experiment, the length of fiber is 50 km corresponding to 10 db losses, the red pulse symbols indicate the measured excess noise and worst-case estimator, the size of block is 109, which corresponding about 2.6 min of data sampling. The blue line shows the threshold of excess noise that can yield positive secret key rate.

Mentions: The fluctuation of excess noise is an important issues. To confirm the impact of uncertainty of the excess noise on the secret key rate in real time, we measured the excess noise on the block with size of 109 over 12 hours at a distance of 50 km, and calculated the key rate in this situation. We use the standard procedure for the excess noise estimation35, and estimate the parameters by randomly sampling m = N − n couples of correlated variables for getting the excess noise. Considering a calibrated shot noise variance , we can achieve a real-time excess noise in Alice’s side as . The result is plotted in Fig. 4. We anticipate that the CVQKD with our technologies should remain effective for longer transmission distance by further controlling the excess noises in the practical CVQKD system.


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)

Experimental excess noise measured over 12 hours with a SNR of 0.9 on Bob’ side.In experiment, the length of fiber is 50 km corresponding to 10 db losses, the red pulse symbols indicate the measured excess noise and worst-case estimator, the size of block is 109, which corresponding about 2.6 min of data sampling. The blue line shows the threshold of excess noise that can yield positive secret key rate.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Experimental excess noise measured over 12 hours with a SNR of 0.9 on Bob’ side.In experiment, the length of fiber is 50 km corresponding to 10 db losses, the red pulse symbols indicate the measured excess noise and worst-case estimator, the size of block is 109, which corresponding about 2.6 min of data sampling. The blue line shows the threshold of excess noise that can yield positive secret key rate.
Mentions: The fluctuation of excess noise is an important issues. To confirm the impact of uncertainty of the excess noise on the secret key rate in real time, we measured the excess noise on the block with size of 109 over 12 hours at a distance of 50 km, and calculated the key rate in this situation. We use the standard procedure for the excess noise estimation35, and estimate the parameters by randomly sampling m = N − n couples of correlated variables for getting the excess noise. Considering a calibrated shot noise variance , we can achieve a real-time excess noise in Alice’s side as . The result is plotted in Fig. 4. We anticipate that the CVQKD with our technologies should remain effective for longer transmission distance by further controlling the excess noises in the practical CVQKD system.

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