The no-masking theorem states that it is impossible to encode an arbitrary quantum state into the correlations between two subsystems so that no original information about is accessible in the marginal state of either subsystem. In this paper, we generalize this theorem to allow for failure of the protocol. We then bound the performance of a masking protocol when we are allowed a (probabilistic) approximate protocol.
@article{arxiv.1912.02419,
title = {Probabilistic and Approximate Masking of Quantum Information},
author = {Mao-Sheng Li and Kavan Modi},
journal= {arXiv preprint arXiv:1912.02419},
year = {2020}
}