No abstract

No abstract

No abstract

No abstract

The generalized n-qubit Greenberger-Horne-Zeilinger (GHZ) states and their local unitary equivalents are the only states of n qubits that are not uniquely determined among pure states by their reduced density matrices of n − 1 qubits. Thus, among pure states, the generalized GHZ states are the only ones containing information at the n-party level. We point out a connection between local unitary stabilizer subgroups and the property of being determined by reduced density matrices. Quantifying and characterizing multi-party quantum entanglement is a fundamental problem in the field of quantum information. Roughly speaking, one expects the states that are "most entangled" to be the most valuable resources for carrying out quantum information processing tasks such as quantum communication and quantum teleportation, and to give the most striking philosophical implications in terms of the rejection of local hidden variable theories [1].