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Q: Fachverband Quantenoptik und Photonik

Q 37: Quantum Information: Concepts and Methods VI

Q 37.7: Vortrag

Mittwoch, 2. März 2016, 16:00–16:15, e214

Anticoherence and entanglement of spin states — •John Martin¹, Dorian Baguette¹, François Damanet¹, Thierry Bastin¹, and Olivier Giraud² — ¹Institut de Physique Nucléaire, Atomique et de Spectroscopie, Université de Liège, 4000 Liège, Belgium — ²LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France

We investigate multiqubit permutation-symmetric states with maximally mixed reduced density matrices in the symmetric subspace [1]. Such states can be viewed as particular spin states, namely anticoherent spin states [2]. Using the Majorana representation of spin states in terms of points on the unit sphere [3], we analyze the consequences of degeneracies of the Majorana points and of a point-group symmetry in their arrangement on the existence of anticoherent spin states. We provide different characterizations of anticoherence and establish a link between point symmetries, anticoherence, and SLOCC classes [4]. We consider in detail the case of small numbers of qubits and solve the 4-qubit case completely by identifying and characterizing all 4-qubit anticoherent states.

[1] D. Baguette, T. Bastin, and J. Martin, Phys. Rev. A 90, 032314 (2014); O. Giraud et al., Phys. Rev. Lett. 114, 080401 (2015); D. Baguette et al., Phys. Rev. A 92, 052333 (2015).

[2] J. Zimba, Electron. J. Theor. Phys. 3, 143 (2006).

[3] E. Majorana, Nuovo Cimento 9, 43 (1932).

[4] SLOCC classes : Classes of states equivalent through stochastic local operations with classical communication.