Entanglement-assisted quantum error-correcting codes from subfield subcodes of projective Reed-Solomon codes

Subfield subcodes of Reed-Solomon codes and their duals, BCH codes, have been widely used for constructing quantum error-correcting codes with good parameters. In this paper, we study subfield subcodes of projective Reed-Solomon codes and their duals, we provide bases for these codes and estimate their parameters. With this knowledge, we can construct symmetric and asymmetric entanglement-assisted quantum error-correcting codes, which in many cases have new or better parameters than the ones available in the literature.