Possible and impossible in the quantum world
Teiko Heinosaari
A standard quantum mechanics textbook is in large extent about energy - it teaches how to calculate energy levels and stationary states of quantum systems, such as atoms. There is an alternative viewpoint to quantum theory that takes information as the central concept of interest. Natural questions are then about the possible and impossible information processing tasks that one can perform with quantum systems and devices. In this talk, I will recall the famous no-cloning theorem of quantum theory and discuss the implications and experimental testability of this theorem. I will then explain some refinements of the no-cloning theorem and it's validity in other theories. From the point of view of quantum information theory, the no-cloning theorem is important but still just a one step in a longer chain of no-go theorems. I will present some of these other no-go theorems and explain their relation to no-cloning.