Erlangen 2018 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 68: Quantum Information (Concepts and Methods) V

Q 68.4: Vortrag

Freitag, 9. März 2018, 11:15–11:30, K 1.019

Entanglement robustness of symmetric multiqubit states — •Antoine Neven, John Martin, and Thierry Bastin — CESAM Research Unit, Institut de Physique Nucléaire, Atomique et de Spectroscopie, Université de Liège, 4000 Liège, Belgium

Detecting the entanglement of a multipartite pure state is a task that can now be addressed using various tools, such as for example, negativity or generalised concurrences. Realising the same task with a mixed state is however still a challenge today. In a situation where some of the parties of a multipartite entangled pure state are lost, the question arises whether the residual mixed state keeps some of the initial entanglement. In this context, entangled pure states that after partial trace keep some entanglement are said to be robust against party loss and those that lose all entanglement (i.e. become separable) are said to be fragile against party loss. In this talk, we investigate the entanglement robustness against party loss of symmetric multiqubit states. We identify all the fragile states for the loss of 1 qubit and show that these fragile states exhibit a particular symmetry and are all SLOCC-equivalent. We also study robustness properties for multiple parties loss and treat exhaustively the case of symmetric states of 4 qubits.