Details

Autor(en) / Beteiligte

• Cormann, Mirko
• Caudano, Yves

Titel

Geometric description of modular and weak values in discrete quantum systems using the Majorana representation

Ist Teil von

• Journal of physics. A, Mathematical and theoretical, 2017-07, Vol.50 (30), p.305302

Ort / Verlag

IOP Publishing

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We express modular and weak values of observables of three- and higher-level quantum systems in their polar form. The Majorana representation of N-level systems in terms of symmetric states of N  −  1 qubits provides us with a description on the Bloch sphere. With this geometric approach, we find that modular and weak values of observables of N-level quantum systems can be factored in N  −  1 contributions. Their modulus is determined by the product of N  −  1 ratios involving projection probabilities between qubits, while their argument is deduced from a sum of N  −  1 solid angles on the Bloch sphere. These theoretical results allow us to study the geometric origin of the quantum phase discontinuity around singularities of weak values in three-level systems. We also analyze the three-box paradox (Aharonov and Vaidman 1991 J. Phys. A: Math. Gen. 24 2315-28) from the point of view of a bipartite quantum system. In the Majorana representation of this paradox, an observer comes to opposite conclusions about the entanglement state of the particles that were successfully pre- and postselected.