State
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.
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
This state is not recorded as a kind of anything else. It stands on its own in the vocabulary.
Narrower kinds of this
- 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.
- Circuit for e^{-iHt}
Time evolution under a Hamiltonian, approximated to a stated error, with the query or gate count and the norm parameter the count is measured against. It is a circuit, not an answer — something still has to run it on a state and read the result.
- Routed circuit
An assignment of logical qubits to physical ones, plus the SWAPs needed to keep every two-qubit gate on an edge the machine actually has. Costed in the depth the routing added, not in the depth you asked for.
- Discrete-gate circuit
Continuous rotations replaced by words in a finite gate set, to a stated precision. The count that matters here is the non-Clifford one, because that is what a fault-tolerant machine charges for.
- Device circuit
Native gates, legal connectivity, and an honest account of what compiling added — SWAP count, non-Clifford count, depth, and the approximation error accumulated on the way down.
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
No recorded process returns this. Either it is where a reader starts — a problem, a matrix, a machine — or it is an object this graph names and no route yet reaches.
Work that starts here
- 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.