Experimental masking of qubit states on arbitrary disks

Quantum information masking (QIM) entails the transmission of quantum information from a single qubit to the entanglement within quantum system, demonstrating promise for utilization in quantum communication. However, the absence of a universal masker capable of masking all qubits restricts its utility in quantum communication and poses a threat to information security. Here we successfully implement the improved QIM method by designing a quantum masking machine capable of masking the set of states on arbitrary disks. The analysis of several sets of target-qubit states proves that our study extends the range of maskable sets in QIM. Through this approach, we devise a scheme for quantum secret sharing (QSS) and demonstrate its feasibility using a proof-of principle experiment. This research results not only provides new experimental evidence for QIM, but also lays a solid foundation for its application in quantum communication.1. IntroductionThroughout history, reliable and secure communication has been crucial for the development and even survival of individuals and nations. Classical cryptosystems rely on computational complexity for encryption, while quantum cryptography [1, 2] leverages the principles of quantum information to offer enhanced levels of security [3–5].Various no-go theorems are essential for improving the security and integrity of quantum communication [6–14]. These theorems imply that certain operations that cannot be performed on quantum states used for transmitting information, such as the no-cloning theorem [15–17], the no-broadcasting theorem [18], the no-deleting theorem [19] and the no-hiding theorem [20, 21], etc. A new no-go theorem, known as the no-masking theorem [22], has recently been discovered and proven in relation to the quantum information masking (QIM) [23–30], a technique utilized for transferring information stored in a single qubit to the entanglement of a multi-qubit system. The no-masking theorem demonstrates that there is no universal masker capable of masking all states of a qubit in two-dimensional Hilbert space. For example, the analysis of the maskable sets shows that only quantum information stored strictly in phase can be masked by one masker. This limitation poses a potential security risk in quantum communication, as unmasked information (e.g., latitude of the Bloch sphere) could be exploited by eavesdroppers.In this paper, we proposes an improved QIM method to mask the set of qubit states on any Bloch sphere disk using a single masker and experimentally demonstrates a QSS scheme based on this approach. This approach can extends the range of maskable sets for QIM by utilizing an adapter to aid a single masker in building the improved quantum masking machine. In particular, we ingeniously apply these maskable sets to QSS to prevent hackers from inferring the transmission state solely from the single reduced qubit, while still allowing both parties to extract information from entanglement for secure communication. Our single-photon experiments have clearly demonstrated how QSS can be effectively implemented on an improved quantum information masking machine, enabling the transmission of a set of quantum states across an arbitrary disk. Our research extends the scope of maskable sets in QIM, proposes a QSS scheme based on these sets, and experimentally verifies its feasibility, thereby expanding the potential applications of QIM.