# Signalling in quantum circuits

Monoidal circuit boards appear in quantum physics to describe families of quantum supermaps. These can be modelled with pointed profunctors and we reason about them using coend calculus (Román, 2020). However, these models also impose some “signalling constraints”. These limit how morphisms can communicate once the circuit board is filled. The present manuscript claims that these can be recovered using the duoidal structure of monoidal profunctors.

**Tags**:
Duoidal Tambara,
Open Diagrams via Coend Calculus (Román, 2020)