A Study on Qubit Information Masking

Quantum information masking, a technique that encodes quantum information into the correlations within a composite system while ensuring that individual subsystems carry no discernible information about the input states, plays a pivotal role in various quantum information processing tasks including quantum bit commitment, quantum secret sharing, quantum error correction, and quantum communication. In this paper, we specifically study the masking of qubit information. Our results demonstrate that when the first qubit of a multi-qubit system is tasked with masking an arbitrary qubit state, the residual qubits are incapable of masking any qubit state. Intriguingly, under these conditions, a recovery operation exists that can perfectly restore the input qubits from the residual qubits, suggesting a complete transfer of the input information to these qubits. Moreover, we uncover that the correlation between the first qubit and the residual qubits might redundantly contain partial information of input qubits. This phenomenon of information redundancy offers a novel viewpoint for comprehending quantum error-correcting codes and contributes to a deeper understanding of quantum information theory. This study elucidates fundamental aspects of quantum information theory and may have potential applications in quantum information processing.