Continuous-variable quantum key distribution (QKD) utilizes an ensemble of coherent states of light to distribute secret encryption keys between two parties in the presence of an eavesdropper (Left). The effect of reconciliation efficiency on the asymptotic secure key rate between distant parties. We proposed some MET-LDPC codes with low FER and high efficiency $\beta$ to obtain a maximum possible secure key rate (Right)

Multiedge-type low-density parity-check codes for continuous-variable quantum key distribution

Tuesday 29 Jun 21
|

Contact

Hossein Mani
Postdoc
DTU Physics

Contact

Tobias Gehring
Associate Professor
DTU Physics
+45 53 67 00 16

Contact

Ulrik Lund Andersen
Professor
DTU Physics
+45 45 25 33 06

Error correction is one of the most important and difficult tasks when generating secret keys with the quantum key distribution. In collaboration with researchers from the Austrian Institute of Technology, we developed new codes which will allow us to achieve higher key rates and longer distances.

Continuous-variable quantum key distribution (QKD) utilizes an ensemble of coherent states of light to distribute secret encryption keys between two parties. An essential ingredient of the QKD protocol is highly efficient information reconciliation.  To achieve highly efficient reconciliation, error-correcting codes with a low channel coding rate are inevitable in the most common schemes of multilevel coding and multistage decoding (MLC-MSD) and multidimensional reconciliation. Multiedge-type (MET) low-density parity-check (LDPC) codes are well suited for highly efficient reconciliation at low rates. Here, we calculate the optimal channel coding rates in the MLC-MSD scheme for reverse reconciliation, introduce the concept of generalized extrinsic information transfer charts for MET-LDPC codes, which constitute a simple and fast asymptotic analysis tool, and present a set of MET-LDPC codes with asymptotic efficiency > 97 %  for channel coding rates 0.1, 0.05, 0.02, and 0.01. We believe that our codes will find wide application in implementations of continuous-variable quantum key distribution based on Gaussian modulation.

Link:

https://journals.aps.org/pra/abstract/10.1103/PhysRevA.103.062419

https://www.bigq.fysik.dtu.dk/news/nyhed?id=%7B01F1E49D-6739-4F96-B14A-6662BFB0000B%7D
25 SEPTEMBER 2021