Skip to Main content Skip to Navigation
Conference papers

PBS-Calculus: A Graphical Language for Coherent Control of Quantum Computations

Abstract : We introduce the PBS-calculus to represent and reason on quantum computations involving coherent control of quantum operations. Coherent control, and in particular indefinite causal order, is known to enable multiple computational and communication advantages over classically ordered models like quantum circuits. The PBS-calculus is inspired by quantum optics, in particular the polarising beam splitter (PBS for short). We formalise the syntax and the semantics of the PBS-diagrams, and we equip the language with an equational theory, which is proved to be sound and complete: two diagrams are representing the same quantum evolution if and only if one can be transformed into the other using the rules of the PBS-calculus. Moreover, we show that the equational theory is minimal. Finally, we consider applications like the implementation of controlled permutations and the unrolling of loops.
Complete list of metadatas
Contributor : Alexandre Clément <>
Submitted on : Thursday, September 3, 2020 - 12:21:33 PM
Last modification on : Friday, September 4, 2020 - 3:29:42 AM

Links full text




Alexandre Clément, Simon Perdrix. PBS-Calculus: A Graphical Language for Coherent Control of Quantum Computations. 45th International Symposium on Mathematical Foundations of Computer Science (MFCS 2020), Aug 2020, Prague, Czech Republic. pp.24:1-24:14, ⟨10.4230/LIPIcs.MFCS.2020.24⟩. ⟨hal-02929291⟩



Record views