FA-90908 / Quantum circuit simulation / Member archive

Collapse outcome test drops parentheses around the bit extraction · case 03

Projecting qubit 1 onto outcome 1 reports "impossible" even when that qubit is certainly excited.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

Input [n, amps, q, outcome]; measure qubit q (0 = LSB) of the possibly unnormalized state. Return {"probability": p, "state": post} with p normalized by the total squared norm and the post-measurement state renormalized to unit norm with the other branch zeroed; values rounded to 6 decimals. Return "impossible" when p < 1e-12.

Why this case matters

Mid-circuit measurement and collapse drive dynamic circuits; wrong renormalization breaks every later probability.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: random collapse 30	`"impossible"`	`{"probability": 0.485806, "state": [[0.0, 0.0], [0.0, 0.0], [-0.300254, -0.364782], [0.641991, -0.198194], [0.0, 0.0], [0.0, 0.0], [0.23836, -0.301571], [-0.163296, 0.388487]]}`	Failed

MEMBER ARCHIVE

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