State
Parameterised circuit family
Not one circuit but a family of them, indexed by free real parameters — a fixed gate structure with the angles left open. Nothing can be run and nothing can be costed until the angles are chosen, so this is deliberately a different object from the circuit it becomes: the structure decides which states are reachable at all, and the choice of angles only decides which of those you land on.
A state is an object you can be holding, named once so that two routes reaching the same thing are drawn as reaching the same thing. It says nothing about how you got here or where you can go next — that is entirely in the processes below.
This is a kind of
Anything that asks for one of these will accept this, because it is narrower. The reverse does not hold.
- Abstract circuit
Arbitrary rotation angles, arbitrary two-qubit gates, and any qubit able to talk to any other. No machine runs this. Everything between here and hardware is the business of closing that gap and counting what it costs.
Narrower kinds of this
No state in the vocabulary is recorded as a narrower kind of this one.
Records that are this object
Nothing in the catalogue has been joined to this state. That is a gap in the join rather than a claim that no such object exists; the shelf on /repository lists what is joined and what is not, with the reason.
Work that arrives here
- Choose a parameterised trial state
Fix the gate structure of a circuit family and leave its rotation angles open. What comes back is not a circuit but the set of states the later optimisation is allowed to search — which is why this is a slot of its own and not a paragraph in one method's write-up.
Work that starts here
- Minimise the objective over the parameters
Search the parameters of a fixed circuit family for the ones that minimise a chosen objective, given that every evaluation of that objective is a noisy estimate someone paid shots for. The output is a routine that prepares one particular state — the family collapsed to a member.
Also accepted where something broader is wanted
These ask for an object this one is a kind of. Narrowing composes in that direction and only that direction: handing on something broader than a process asks for would be a skipped conversion.
- Compile a circuit to a specific device
Turn a circuit written as arbitrary unitaries over abstract qubits into an executable instruction sequence for one machine's own gate set and connectivity graph. The result is functionally equivalent, or equivalent to within a stated approximation error.
- Satisfy the hardware connectivity constraint
Place logical qubits on physical ones and schedule connectivity-repair operations — usually SWAPs — so that every two-qubit gate acts on a coupled pair. The problem combines subgraph isomorphism with token swapping.
- Approximate a continuous rotation in a discrete gate set
Given a target single-qubit unitary — typically a z-rotation by an arbitrary angle — and a precision , produce a finite word over a fixed discrete gate set such as Clifford+T whose product is within of the target in a stated metric. The cost is charged in non-Clifford gates.