4,582 research outputs found
Coherent control of multipartite entanglement
Quantum entanglement between an arbitrary number of remote qubits is examined
analytically. We show that there is a non-probabilistic way to address in one
context the management of entanglement of an arbitrary number of mixed-state
qubits by engaging quantitative measures of entanglement and a specific
external control mechanism. Both all-party entanglement and weak inseparability
are considered. We show that for , the death of all-party entanglement
is permanent after an initial collapse. In contrast, weak inseparability can be
deterministically managed for an arbitrarily large number of qubits almost
indefinitely. Our result suggests a picture of the path that the system
traverses in the Hilbert space
Bounding the entanglement of N qubits with only four measurements
We introduce a new measure for the genuinely N-partite (all-party)
entanglement of N-qubit states using the trace distance metric, and find an
algebraic formula for the GHZ-diagonal states. We then use this formula to show
how the all-party entanglement of experimentally produced GHZ states of an
arbitrary number of qubits may be bounded with only four measurements
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