Quantum repeaters based on concatenated bosonic and discrete-variable quantum codes

• DOI: 10.1038/s41534-021-00438-7
• Publication Date: 2021-06-22T10:02:49Z
• Authors: Filip Rozpędek; Kyungjoo Noh; Qian Xu; Saikat Guha; Liang Jiang
• Keywords: Quantum Physics; Physics; QC1-999; Electronic computers. Computer science; 0103 physical sciences; FOS: Physical sciences; QA75.5-76.95; Quantum Physics (quant-ph); 01 natural sciences

AbstractWe propose an architecture of quantum-error-correction-based quantum repeaters that combines techniques used in discrete- and continuous-variable quantum information. Specifically, we propose to encode the transmitted qubits in a concatenated code consisting of two levels. On the first level we use a continuous-variable GKP code encoding the qubit in a single bosonic mode. On the second level we use a small discrete-variable code. Such an architecture has two important features. Firstly, errors on each of the two levels are corrected in repeaters of two different types. This enables for achieving performance needed in practical scenarios with a reduced cost with respect to an architecture for which all repeaters are the same. Secondly, the use of continuous-variable GKP code on the lower level generates additional analog information which enhances the error-correcting capabilities of the second-level code such that long-distance communication becomes possible with encodings consisting of only four or seven optical modes.