24
votes
Accepted
What is postselection in quantum computing?
"Postselection" refers to the process of conditioning on the outcome of a measurement on some other qubit. (This is something that you can think of for classical probability distributions and ...
- 11k
10
votes
What is postselection in quantum computing?
As the other answer conveyed (and to which I am just trying to provide some clarification), post-selection is about just looking at a subset of possible measurement outcomes. To my mind, this falls ...
- 47.6k
4
votes
Accepted
HHL algorithm -- problem with the outcome of postselection
Your intuition is correct for a single qubit, in that if I measure $$\alpha\vert 0 \rangle + \beta\vert 1 \rangle$$ I would get either $\vert 0 \rangle$ or $\vert 1 \rangle$. But since the qubits are ...
- 1,676
3
votes
HHL algorithm -- problem with the outcome of postselection
You are half right, in that the $C$ factor is only kept there for (what I assume being) explanatory purposes.
However, the $1/\lambda_j$ factors definitely stays there after postselection. One way to ...
glS♦
- 19.1k
1
vote
How to select the statevetor of a qubit in a multiqubit circuit in qiskit?
You can use save_statevector with conditional = True, like that:
...
- 4,918
1
vote
Post-selection applied to quantum teleportation
As I understand it, the key caveat to postselection, at least in regards to retrocausal effects, is that Bob already knows what state Alice will post-select. Since he already knows what she will do, ...
- 1,123
1
vote
On the probability of preparing of a uniform superposition by performing a controlled-multiplication and post-selecting $0$
CW from self-answer, and also because this is more of an extended comment than an answer.
Let $A$ be the adjacency matrix of the Cayley graph of our group $\mathcal{H}$ of order $N$. Notice that $A$ ...
1
vote
Accepted
How is postselection used in quantum tomography?
In principle, Bob here just has to guess the $2\times 2$ matrix $\sigma$.
If he starts with any parametric state $\sigma(\alpha,\beta)$ with $\alpha,\beta\in\mathbb{C}$ and measures the outcome Tr$(M\...
- 1,605
Only top scored, non community-wiki answers of a minimum length are eligible