Superhero movies have taught a broad audience the tantalizing notion of parallel universes: universes just like ours containing doppelgangers of all of us, but in which different life choices have resulted in small or large differences. In most franchises, these parallel universes evolve independently of our own, until a sorcerer opens some kind of portal allowing protagonists to travel the multiverse.
Beyond superhero comics, the equations of quantum mechanics can be interpreted to state that amazingly, parallel universes exist also in our actual physical reality. These actual parallel universes are simultaneously less and more fun than the parallel universes of fantasy and science fiction stories: On the one hand, these actual parallel universes cannot be traveled to. On the other, they continuously interfere with each other, not only after a portal has been opened.
Moreover, many physical phenomena can only be explained with this continuous interference of parallel universes. Mirrors and photosynthesis, for instance, but also quantum computers. Quantum computers operate in a much more subtle manner than "trying computations in parallel, distributed across universes" as somehow depicted in popular accounts of quantum computing.
This talk provides a leisurely introduction to this circle of ideas, aimed at people who would like to understand what modern physics has to say about the multiverse. The talk will culminate in a discussion of a certain quantum algorithm providing exponential speedup over its classical cousin.
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