Anomaly of non-locality and entanglement in teaching quantum information

Abstract

Non-locality and quantum entanglement constitute two special features of quantum systems of enormous relevance in quantum information theory (QIT). Historically regarded as identical or equivalent for many years, they constitute different concepts. We want to stress in the present contribution such difference which actually may guide the instructor to cover the most essential topics of QIT in any section of some introductory course. We shall address the simplest possible case of that of two qubits. The material may be of interest to instructors teaching high-undergraduate quantum mechanics, as well as students.