Professor Patrick Hayden of the Stanford Institute for Theoretical Physics (SITP) introduces the science of quantum information.
Over the past sixty years, computers have shrunk, networks have spread and flickering bits of information have ever more thoroughly infiltrated all aspects of our lives. The boundary between the virtual world of information and the physical world we ultimately inhabit has been slowly fading to the point that it is becoming hard to tell where one ends and the other begins. But deep down, we know there is a difference. Information is an invented abstraction: engineered, processed and repackaged but not the basic stuff of reality. Or perhaps not. The fundamental laws of physics, in the form of quantum mechanics, force physicists to wrestle with the very meaning of information. If Schrodinger’s cat can be both alive and dead, then the familiar “bit” isn’t up to the task of describing her state.
With gathering speed, scientists have been developing the science of truly quantum mechanical information. Not only is it strange, it has proven to be useful. Quantum computers could solve problems no digital computer will ever be able tackle. Quantum cryptosystems could only be cracked by violating the laws of physics. In these lectures, we’ll explore the nature of quantum information and how to use it. We’ll end by applying those pragmatic ideas to the nature of spacetime itself, finding that the boundary between the virtual and physical worlds is far fuzzier than we could have imagined.