Guided tour · Foundations · step 2 of 11
Correlation is what entanglement looks like
A Bell pair and two independent coin flips are identical in a histogram. The difference only shows in the correlations.
First, commit to an answer
Two circuits: one entangles two qubits, the other puts each in its own superposition. Which histogram tells them apart?
Decide before you follow the link. Nothing is recorded — the value is in having been wrong on purpose once.
Now go and look
Look at the correlation panel, then replace the cx line with h q[1]; and look again.
What you should see
Neither histogram tells them apart — both are 50/50 on each qubit. The correlation panel reports a correlated pair for the first and a product state for the second.