Definition: A finite Enter experiment on the background

An experiment consists of the following data.

1. External geometry. The fixed configuration

   $$(\overline{M},M,g,N=1,\mathcal{W},U,\chi ,c).$$

2. Names and locations. At each semantic cut there is a finite set of live quantum names. Their Hilbert spaces are finite tensor products of qubits. A location map assigns each accessible port to a point of $M$. Several names may be co-located.

3. Accessible algebras. For a declared local collection $A$ of live names, the accessible algebra is the full matrix algebra on those names, tensored with the identity on other live names. A smaller algebra may be declared, but no subsequent operation may silently use an observable outside it.

4. Complete control and resources. A finite instruction tree specifies allocations, permitted unitaries, destructive readouts, classical controls, input and output ports, schedules, location data, retained storage, and all auxiliary factors. Every classical control dependency is either preinstalled task data or a declared causal record wire.

The background metric has no state-dependent update rule in this model.