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Quantum steganography is the art of hiding the fact that communications, which transmit the secret message in an insecure quantum channel, are occurring. This paper presents a novel quantum steganography protocol based on probability measurements for transmitting n qubits secret message in an insecure quantum channel. In the protocol, senders embed the secret message into the cover data by POVM measurements. Then, receivers can correctly extract the secret message and recover the cover data with a certain probability by selecting two sets of appropriate protective measurement operators to act projective measurements, respectively. More importantly, the existence of the secret message has no influence on the cover data. In addition, the security of our protocol does not rely on other protocols. The paper analyzes the secrecy and the security in detail. [ABSTRACT FROM AUTHOR]

We propose a deterministic scheme to realize assisted-clone of an unknown N(≥3)-qubit entangled state. The first stage of the protocol requires teleportation via maximal entanglement as the quantum channel. In the second stage of the protocol, a novel set of mutually orthogonal basis vectors are constructed. With the assistance of the preparer through an N-particle projective measurement under this basis, the perfect copy of an original state can be produced. Comparing with the previous protocols which produce the unknown state and its orthogonal complement state at the site of the sender, our scheme generates the unknown state deterministically. [ABSTRACT FROM AUTHOR]