State
Bias-reduced expectation value
The same number after post-processing, with less bias and more variance. The variance is a sampling overhead and it grows with circuit volume, which is what bounds how far mitigation alone can be pushed.
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.
- Number with an error bar
A scalar estimate with an additive-error guarantee, the shot or query budget it consumed, and the deepest circuit it actually ran. Every claim about an application eventually has to arrive here.
- Answer about the solution
Whatever a route hands back about the state of the system at the end — a state you can measure, a history over the whole interval, or a single number. Which of the three you get is a real difference between routes, so each is its own kind below this one.
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
- Recover a noiseless expectation value by post-processing
Estimate what an observable would have measured on a noiseless device by running modified or repeated circuits on the noisy one and combining the results classically. No qubits are spent on redundancy; the whole price is paid in shots.
Work that starts here
No recorded process takes this as its input. Nothing in this graph leaves from here.