Strong monogamy of entanglement

Strong monogamy of entanglement

Seminar author:Sara di Martino

Event date and time:06/02/2014 02:30:pm

Event location:IFAE seminar room

Event contact:

Understanding the structure of entanglement distributed among many parties is central to diverse aspects of quan- tum information theory. In 2000 Coffman et al found that the entanglement that can be shared among three parties (A, B, C) is constrained by the so-called monogamy inequalities.

After some years Osborne et al found that a set of similar inequalities holds for systems of n qubits: the sum of the entanglement that one qubit shares with each one of the other qubits of the system is bounded from above by the entanglement that this qubit shares with the rest of the system.

We investigate the generalization of these inequalities for four-qubit pure states where all the possible bipartition of the system are taken into account. In particular we prove that some classes of states, as the one composed by states that are superpositions of four-partite GHZ and W states, satisfy a strong monogamy inequality, by constructing a lower bound on the measure of entanglement. We also show numerical evidence that the inequality holds for arbitrary pure states of four qubits.