protecting entanglement between logical qubits via quantum error correction

Our work demonstrates the experimental protection of quantum entanglement between logical qubits through quantum error correction. Figure 2 shows The repetitive quantum error correction on a single logical qubit, while Figure 3 illustrates the protection of entanglement through repetitive quantum error correction. The coherence time of the ELQ is improved by 45% compared with the unprotected ELQ and exceeds that of the entangled physical qubits. Moreover, in figure 4, violation of the Bell inequality by logical qubits is demonstrated for the first time with the measured Bell signal B = 2.250 ± 0.019 after purification via error detection, surpassing the classical bound by 13 standard deviations. All data need to be opened using Matlab.