title: Aligning reference frames with quantum states.
abstract: We analyze the problem of sending, in a single transmission, the information required to specify an orthogonal trihedron or reference frame through a quantum channel made out of N elementary spins. We analytically obtain the optimal strategy, i.e., the best encoding state and the best measurement. For large N, we show that the average error goes to zero linearly in 1/N. Finally, we discuss the construction of finite optimal measurements.
authors.affiliation: Grup de Física Teòrica & IFAE, Facultat de Ciències, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Bagan
authors.forename: M
authors.initials: M
authors.lastname: Baig
authors.forename: R
authors.initials: R
authors.lastname: Muñoz-Tapia