There are many quantum computers around, IBM and Google's supper conducting ones, our ion traps, optical ones by e.g. Quandela, and they are all heavily used.

There are many quantum computers around, IBM and Google's supper conducting ones, our ion traps, optical ones by e.g. Quandela, and they are all heavily used. There exist compilers for them and they heavily employ ZX-calculus for optimisation. ZX-calculus is also the main language for optical quantum computing. Within the year we expect them to do a task that is impossible on classical hardware within a realistic timeframe. Btw ZX-calculus as part of categorical quantum mechanics is an alternative formalism for QM, independent of quantum computing. It has been proven to be complete for Hilbert space and linear maps.