FA-90906 / Quantum circuit simulation / Open access

Collapse outcome test drops parentheses around the bit extraction · case 01

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

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The branch predicate compares the masked value i & (1 << q), which is 0 or 2**q, directly to the outcome 0 or 1.

THE FAILURE

The branch predicate compares the masked value i & (1 << q), which is 0 or 2**q, directly to the outcome 0 or 1.

Unsuccessful approach: The attempted repair tests bool(i & (1 << q)) is outcome, an identity check between bool and int that is never true for outcome 1.

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.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    n, amps, q, outcome = x
    psi = [complex(a, b) for a, b in amps]
    keep = [(i & (1 << q)) == outcome for i in range(len(psi))]
    p = sum(abs(v) ** 2 for i, v in enumerate(psi) if keep[i])
    norm = sum(abs(v) ** 2 for v in psi)
    prob = p / norm
    if prob < 1e-12:
        return 'impossible'
    scale = 1 / math.sqrt(p)
    post = [v * scale if keep[i] else 0j for i, v in enumerate(psi)]
    return {'probability': round(prob, 6) + 0.0, 'state': [[round(v.real, 6) + 0.0, round(v.imag, 6) + 0.0] for v in post]}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['repair check: measure 0 on |+>', [1, [[0.707107, 0], [0.707107, 0]], 0, 0], {'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0]]}], ['control: impossible outcome', [1, [[1, 0], [0, 0]], 0, 1], 'impossible'], ['control: near impossible branch', [1, [[1, 0], [1e-08, 0]], 0, 1], 'impossible'], ['control: random collapse 1', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, -0.0], [-0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 2', [2, [[0.0, 0.0], [0.0, 0.0], [0.591, 0.404], [0.405, 0.306]], 1, 0], 'impossible']], [['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['repair check: unnormalized bell measure qubit 1', [2, [[2, 0], [0, 0], [0, 0], [2, 0]], 1, 0], {'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0]]}], ['control: random collapse 7', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, 0.0], [0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 12', [1, [[0.5, 0.0], [0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 16', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, -0.0], [-0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 22', [2, [[0.5, 0.0], [-0.0, -0.0], [0.0, 0.0], [-0.0, -0.0]], 0, 1], 'impossible']], [['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['repair check: random collapse 0', [1, [[-0.305, 0.494], [0.447, -0.241]], 0, 0], {'probability': 0.566536, 'state': [[-0.525346, 0.850889], [0.0, 0.0]]}], ['control: random collapse 23', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 34', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, 0.0], [-0.0, 0.0]], 1, 1], 'impossible'], ['control: random collapse 37', [3, [[0.5, 0.0], [-0.0, -0.0], [0.0, -0.0], [0.0, 0.0], [0.0, -0.0], [-0.0, 0.0], [-0.0, -0.0], [-0.0, 0.0]], 0, 1], 'impossible'], ['control: impossible outcome', [1, [[1, 0], [0, 0]], 0, 1], 'impossible']], [['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['repair check: random collapse 4', [1, [[-0.125, -0.177], [0.075, 0.432]], 0, 0], {'probability': 0.196294, 'state': [[-0.576864, -0.81684], [0.0, 0.0]]}], ['control: near impossible branch', [1, [[1, 0], [1e-08, 0]], 0, 1], 'impossible'], ['control: random collapse 1', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, -0.0], [-0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 2', [2, [[0.0, 0.0], [0.0, 0.0], [0.591, 0.404], [0.405, 0.306]], 1, 0], 'impossible'], ['control: random collapse 7', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, 0.0], [0.0, 0.0]], 0, 1], 'impossible']], [['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['repair check: random collapse 6', [3, [[-0.436, -0.015], [-0.35, 0.017], [0.17, 0.002], [0.369, -0.461], [0.411, -0.033], [-0.475, 0.29], [0.379, -0.067], [-0.298, 0.408]], 2, 0], {'probability': 0.438863, 'state': [[-0.524618, -0.018049], [-0.421138, 0.020455], [0.204553, 0.002407], [0.444, -0.554699], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0]]}], ['control: random collapse 12', [1, [[0.5, 0.0], [0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 16', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, -0.0], [-0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 22', [2, [[0.5, 0.0], [-0.0, -0.0], [0.0, 0.0], [-0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 23', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, -0.0]], 0, 1], 'impossible']]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

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
regression: random collapse 38	`impossible`	`{'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}`	Failed
repair check: measure 0 on \|+>	`{'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0]]}`	`{'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0]]}`	Passed
control: impossible outcome	`impossible`	`impossible`	Passed
control: near impossible branch	`impossible`	`impossible`	Passed
control: random collapse 1	`impossible`	`impossible`	Passed
control: random collapse 2	`impossible`	`impossible`	Passed

SHA-256 / 454dc9bc1af51a86392f647b5b7f3fa286608e4851d375ccfe655b969b1223ba

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    n, amps, q, outcome = x
    psi = [complex(a, b) for a, b in amps]
    keep = [bool(i & (1 << q)) is outcome for i in range(len(psi))]
    p = sum(abs(v) ** 2 for i, v in enumerate(psi) if keep[i])
    norm = sum(abs(v) ** 2 for v in psi)
    prob = p / norm
    if prob < 1e-12:
        return 'impossible'
    scale = 1 / math.sqrt(p)
    post = [v * scale if keep[i] else 0j for i, v in enumerate(psi)]
    return {'probability': round(prob, 6) + 0.0, 'state': [[round(v.real, 6) + 0.0, round(v.imag, 6) + 0.0] for v in post]}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['repair check: measure 0 on |+>', [1, [[0.707107, 0], [0.707107, 0]], 0, 0], {'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0]]}], ['control: impossible outcome', [1, [[1, 0], [0, 0]], 0, 1], 'impossible'], ['control: near impossible branch', [1, [[1, 0], [1e-08, 0]], 0, 1], 'impossible'], ['control: random collapse 1', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, -0.0], [-0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 2', [2, [[0.0, 0.0], [0.0, 0.0], [0.591, 0.404], [0.405, 0.306]], 1, 0], 'impossible']], [['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['repair check: unnormalized bell measure qubit 1', [2, [[2, 0], [0, 0], [0, 0], [2, 0]], 1, 0], {'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0]]}], ['control: random collapse 7', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, 0.0], [0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 12', [1, [[0.5, 0.0], [0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 16', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, -0.0], [-0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 22', [2, [[0.5, 0.0], [-0.0, -0.0], [0.0, 0.0], [-0.0, -0.0]], 0, 1], 'impossible']], [['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['repair check: random collapse 0', [1, [[-0.305, 0.494], [0.447, -0.241]], 0, 0], {'probability': 0.566536, 'state': [[-0.525346, 0.850889], [0.0, 0.0]]}], ['control: random collapse 23', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 34', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, 0.0], [-0.0, 0.0]], 1, 1], 'impossible'], ['control: random collapse 37', [3, [[0.5, 0.0], [-0.0, -0.0], [0.0, -0.0], [0.0, 0.0], [0.0, -0.0], [-0.0, 0.0], [-0.0, -0.0], [-0.0, 0.0]], 0, 1], 'impossible'], ['control: impossible outcome', [1, [[1, 0], [0, 0]], 0, 1], 'impossible']], [['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['repair check: random collapse 4', [1, [[-0.125, -0.177], [0.075, 0.432]], 0, 0], {'probability': 0.196294, 'state': [[-0.576864, -0.81684], [0.0, 0.0]]}], ['control: near impossible branch', [1, [[1, 0], [1e-08, 0]], 0, 1], 'impossible'], ['control: random collapse 1', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, -0.0], [-0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 2', [2, [[0.0, 0.0], [0.0, 0.0], [0.591, 0.404], [0.405, 0.306]], 1, 0], 'impossible'], ['control: random collapse 7', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, 0.0], [0.0, 0.0]], 0, 1], 'impossible']], [['regression: random collapse 30', [3, [[0.618, -0.65], [0.455, 0.369], [-0.456, -0.554], [0.975, -0.301], [-0.036, -0.541], [-0.999, 0.041], [0.362, -0.458], [-0.248, 0.59]], 1, 1], {'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]]}], ['regression: random collapse 38', [3, [[-0.953, -0.176], [0.648, 0.073], [-0.664, 0.641], [0.089, 0.712], [0.707, 0.159], [0.7, -0.359], [0.128, 0.001], [0.766, 0.55]], 1, 1], {'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}], ['repair check: random collapse 6', [3, [[-0.436, -0.015], [-0.35, 0.017], [0.17, 0.002], [0.369, -0.461], [0.411, -0.033], [-0.475, 0.29], [0.379, -0.067], [-0.298, 0.408]], 2, 0], {'probability': 0.438863, 'state': [[-0.524618, -0.018049], [-0.421138, 0.020455], [0.204553, 0.002407], [0.444, -0.554699], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, 0.0]]}], ['control: random collapse 12', [1, [[0.5, 0.0], [0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 16', [2, [[0.5, 0.0], [-0.0, 0.0], [0.0, -0.0], [-0.0, 0.0]], 0, 1], 'impossible'], ['control: random collapse 22', [2, [[0.5, 0.0], [-0.0, -0.0], [0.0, 0.0], [-0.0, -0.0]], 0, 1], 'impossible'], ['control: random collapse 23', [2, [[0.5, 0.0], [0.0, 0.0], [0.0, 0.0], [0.0, -0.0]], 0, 1], 'impossible']]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

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
regression: random collapse 38	`impossible`	`{'probability': 0.475302, 'state': [[0.0, 0.0], [0.0, 0.0], [-0.440491, 0.425233], [0.059042, 0.472334], [0.0, 0.0], [0.0, 0.0], [0.084914, 0.000663], [0.508157, 0.364864]]}`	Failed
repair check: measure 0 on \|+>	`impossible`	`{'probability': 0.5, 'state': [[1.0, 0.0], [0.0, 0.0]]}`	Failed
control: impossible outcome	`impossible`	`impossible`	Passed
control: near impossible branch	`impossible`	`impossible`	Passed
control: random collapse 1	`impossible`	`impossible`	Passed
control: random collapse 2	`impossible`	`impossible`	Passed

SHA-256 / dea5b7965df5fdd9256751e3ee00a054bb01293492d4543194f1c6515e830c56

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

A deterministic bounded teaching model with a stipulated toy contract; amplitudes are rounded to fixed decimals for strict JSON output. It is not a production quantum SDK and claims no standards conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:51:30.994928+00:00.

Case digest / d06031e64c52e2b366f6824fc7eb04936980836b1d210d2e4a3e430cb01fe38c