It is something like an axiom for our subject that information is physical and at its most fundamental level this means quantum. Practical quantum processors have to respect the constraints of quantum mechanics and so working towards them challenges us to refine our understanding of the theory. In the first part of my talk I shall discuss some of the practical and fundamental limitations for quantum logic elements. In the second part, I shall describe some of the ways in which studying quantum information has led us to refine our description of quantum measurements.