Seminar by Nicolas Menicucci – University of Copenhagen

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Seminar by Nicolas Menicucci

Title: Gigantic quantum computers made of laser light

Quantum computers promise ultra-fast computation, but to be useful they need to be big -- really big. I will discuss recent theoretical and experimental breakthroughs in designing and building a huge quantum computer made out of laser light itself. The key component to such a quantum computer is a special type of entangled state called a continuous-variable cluster state. These states are are simple to make using lasers and can be scaled up with ease to gigantic sizes. Once in possession of such a state, measurements alone enable full quantum computation, with the choice of measurements determining the computation to be performed. This is surprising because it means one can quantum compute simply by *looking* at a quantum system in a particular way. In this talk, I will describe the basics of measurement-based quantum computing using continuous-variable cluster states, including a crucial recent result showing that noise in such systems is tolerable. I will also report on their experimental realisations, including two recent demonstrations: a 60-mode cluster state and a one-million-mode (!) cluster state. In addition to shattering world records for the number of quantum objects entangled together, these states are prototypes for the basic building block of an ultra-large-scale quantum computer.