The geometry of parallelism: Classical, probabilistic, and quantum effects

We introduce a Geometry of Interaction model for higher-order quantum computation, and prove its adequacy for a fully fledged quantum programming language in which entanglement, duplication, and recursion are all available. This model is an instance of a new framework which captures not only quantum but also classical and probabilistic computation. Its main feature is the ability to model commutative effects in a parallel setting. Our model comes with a multi-token machine, a proof net system, and a PCF-style language. Being based on a multi-token machine equipped with a memory, it has a concrete nature which makes it well suited for building low-level operational descriptions of higher-order languages.