Attività del Dipartimento

A scanner darkly - Generalised measurements in quantum information

Marco Barbieri

After a century of solid training in quantum mechanics, we are now well aware that the act of measurement is not harmless and passive inspection, but it is quite intrusive in the evolution of the system we want to observe. Still, there exist possibility that we can simply take a glance at a system and reduce the perturbation we induce. There is yet a price to pay in terms of the information we get with these generalised measurements.
 
In this talk we will first review the concepts and the methods behind such generalised, weak measurements, and then move on to discussing their application to quantum technologies – with a particular attention to communications and metrology. We will discuss how they can be implemented in a laboratory, what advantages they might (or might not!) provide over standard measurement schemes, and highlight how their results are at odds with a simple, intuitive interpretation of quantum phenomena.