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Paper 1

High-throughput GPU layered decoder of quasi-cyclic multi-edge type low density parity check codes in continuous-variable quantum key distribution systems

Yang Li, Xiaofang Zhang, Yong Li, Bingjie Xu, Li Ma, Jie Yang, Wei Huang

Year

2020

Journal

Scientific Reports

DOI

10.1038/s41598-020-71534-5

arXiv

-

Abstract The decoding throughput during post-processing is one of the major bottlenecks that occur in a continuous-variable quantum key distribution (CV-QKD) system. In this paper, we propose a layered decoder to decode quasi-cyclic multi-edge type LDPC (QC-MET-LDPC) codes using a graphics processing unit (GPU) in continuous-variable quantum key distribution (CV-QKD) systems. As described herein, we optimize the storage methods related to the parity check matrix, merge the sub-matrices which are unrelated, and decode multiple codewords in parallel on the GPU. Simulation results demonstrate that the average decoding speed of LDPC codes with three typical code rates, i.e., 0.1, 0.05 and 0.02, is up to 64.11 Mbits/s, 48.65 Mbits/s and 39.51 Mbits/s, respectively, when decoding 128 codewords of length $${10}^{{6}}$$ 10 6 simultaneously without early termination.

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Paper 2

CH$_4\cdot$F$^-$ revisited: Full-dimensional ab initio potential energy surface and variational vibrational states

Dóra Papp, Viktor Tajti, Gustavo Avila, Edit Mátyus, Gábor Czakó

Year

2022

Journal

arXiv preprint

DOI

arXiv:2209.04306

arXiv

2209.04306

The automated development of a new ab initio full-dimensional potential energy surface (PES) is reported for the CH$_4\cdot$F$^-$ complex using the ROBOSURFER program package. The new potential provides a near-spectroscopic quality description over a broad configuration range including the methane-ion dissociation, as well as isolated methane vibrations. In particular, it improves upon the earlier [Czakó, Braams, Bowman (2008)] PES over intermediate methane-fluoride distances. Full-dimensional (12D) variational vibrational computations using the new PES and the GENIUSH-Smolyak algorithm show that tunneling splittings larger than 0.1 cm$^{-1}$ appear below the top of the interconversion barrier of the four equivalent minima of the complex.

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