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FA-91016 / Quantum circuit simulation / Open access

Depth scheduler treats an empty barrier as a no-op · case 01

A bare barrier after deep work on qubit 0 does not delay a following gate on qubit 2.

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

ROOT CAUSE

An empty qubit list is skipped instead of expanding to every qubit in the circuit.

VERIFIED REPAIR

Expand an empty barrier to all qubits before aligning levels.

Unsuccessful approach: The attempted repair expands only to qubits that already have work, leaving idle qubits unaligned.

Case contract

Input [nq, nc, ops]; ops are [name, qubits], ["measure", [q], [c]], ["g", [q], "if", c] (classically conditioned), ["barrier", qubits] (empty list = all qubits) and ["id", [q]]. ASAP layering: each op lands one layer after the latest of its qubits and any clbit it reads or writes, and sets those levels; barriers align the listed qubits to their maximum without adding a layer; id costs nothing. Return [depth, qubit levels].

Why this case matters

Depth drives decoherence budgets and transpiler choices; scheduling slips misreport circuit cost.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    nq, nc, ops = x
    ql = [0] * nq
    cl = [0] * nc
    for op in ops:
        name, qs = op[0], op[1]
        if name == 'barrier':
            if not qs:
                continue
            top = max(ql[q] for q in qs)
            for q in qs:
                ql[q] = top
            continue
        if name == 'id':
            continue
        cbits = []
        if name == 'measure':
            cbits = op[2]
        elif len(op) > 2 and op[2] == 'if':
            cbits = [op[3]]
        level = 1 + max([ql[q] for q in qs] + [cl[c] for c in cbits])
        for q in qs:
            ql[q] = level
        for c in cbits:
            cl[c] = level
    return [max(ql + cl + [0]), ql]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: partial barrier', [3, 1, [['h', [0]], ['barrier', [0, 1]], ['x', [1]], ['x', [2]]]], [2, [1, 2, 1]]], ['control: toffoli waits on all', [3, 0, [['h', [2]], ['h', [2]], ['ccx', [0, 1, 2]], ['x', [0]]]], [4, [4, 3, 3]]], ['control: cx waits on target', [2, 0, [['h', [1]], ['h', [1]], ['cx', [0, 1]]]], [3, [3, 3]]], ['control: identity is free', [1, 0, [['id', [0]], ['id', [0]], ['x', [0]]]], [1, [1]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: conditioned gate after measure', [2, 1, [['h', [0]], ['measure', [0], [0]], ['x', [1], 'if', 0]]], [3, [2, 3]]], ['control: measure after conditioned read', [2, 1, [['h', [0]], ['h', [0]], ['h', [0]], ['x', [1], 'if', 0], ['measure', [1], [0]]]], [3, [3, 2]]], ['control: empty circuit', [2, 1, []], [0, [0, 0]]], ['control: late read then early-qubit measure', [2, 1, [['h', [1]], ['h', [1]], ['h', [1]], ['x', [1], 'if', 0], ['measure', [0], [0]]]], [5, [5, 4]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: read then measure other clbit writer', [3, 2, [['h', [2]], ['h', [2]], ['z', [2], 'if', 1], ['measure', [0], [1]], ['x', [1], 'if', 1]]], [5, [4, 5, 3]]], ['control: random schedule 0', [1, 2, [['x', [0]], ['rz', [0]], ['measure', [0], [0]], ['x', [0]], ['barrier', [0]], ['x', [0], 'if', 1], ['x', [0], 'if', 1], ['x', [0]], ['measure', [0], [0]]]], [8, [8]]], ['control: random schedule 1', [4, 2, [['ccx', [1, 0, 3]], ['ccx', [2, 1, 3]], ['barrier', [0, 1, 2, 3]], ['cx', [1, 0]], ['id', [1]], ['cx', [1, 2]], ['cx', [0, 2]]]], [5, [5, 4, 5, 2]]], ['control: random schedule 2', [1, 1, [['h', [0]], ['rz', [0]], ['x', [0]], ['x', [0], 'if', 0], ['x', [0]], ['x', [0]], ['x', [0], 'if', 0], ['id', [0]]]], [7, [7]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: random schedule 3', [1, 2, [['h', [0]], ['h', [0]]]], [2, [2]]], ['control: random schedule 4', [4, 1, [['measure', [3], [0]], ['ccx', [2, 1, 0]], ['ccx', [0, 2, 3]]]], [2, [2, 1, 2, 2]]], ['control: random schedule 5', [3, 2, [['ccx', [0, 1, 2]], ['ccx', [2, 1, 0]], ['barrier', [0, 1, 2]], ['x', [1]]]], [3, [2, 3, 2]]], ['control: random schedule 6', [4, 2, [['barrier', [2]], ['cx', [1, 2]], ['ccx', [2, 3, 0]]]], [2, [2, 1, 2, 2]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: random schedule 7', [4, 2, [['x', [2], 'if', 1], ['x', [1]], ['barrier', [2]], ['cx', [0, 1]], ['h', [2]]]], [2, [2, 2, 2, 0]]], ['control: random schedule 8', [1, 1, [['x', [0], 'if', 0], ['rz', [0]], ['rz', [0]], ['h', [0]], ['rz', [0]], ['h', [0]], ['measure', [0], [0]], ['rz', [0]]]], [8, [8]]], ['control: random schedule 9', [3, 1, [['cx', [2, 1]], ['h', [1]], ['barrier', [1, 2]]]], [2, [0, 2, 2]]], ['control: random schedule 10', [4, 1, [['id', [2]]]], [0, [0, 0, 0, 0]]]]]
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 fixtureActualExpectedOutcome
regression: barrier aligns everything[2, [2, 0, 1]][3, [2, 2, 3]]Failed
regression: random schedule 37[3, [3, 0, 3]][4, [4, 3, 3]]Failed
regression: random schedule 47[4, [4, 4, 1, 3]][4, [4, 4, 2, 3]]Failed
control: partial barrier[2, [1, 2, 1]][2, [1, 2, 1]]Passed
control: toffoli waits on all[4, [4, 3, 3]][4, [4, 3, 3]]Passed
control: cx waits on target[3, [3, 3]][3, [3, 3]]Passed
control: identity is free[1, [1]][1, [1]]Passed

SHA-256 / c189cd86011f73385b6dd998afb67a55195fd88614e104f02b35f1cd179b0299

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    nq, nc, ops = x
    ql = [0] * nq
    cl = [0] * nc
    for op in ops:
        name, qs = op[0], op[1]
        if name == 'barrier':
            qs = qs or [q for q in range(nq) if ql[q]]
            top = max(ql[q] for q in qs)
            for q in qs:
                ql[q] = top
            continue
        if name == 'id':
            continue
        cbits = []
        if name == 'measure':
            cbits = op[2]
        elif len(op) > 2 and op[2] == 'if':
            cbits = [op[3]]
        level = 1 + max([ql[q] for q in qs] + [cl[c] for c in cbits])
        for q in qs:
            ql[q] = level
        for c in cbits:
            cl[c] = level
    return [max(ql + cl + [0]), ql]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: partial barrier', [3, 1, [['h', [0]], ['barrier', [0, 1]], ['x', [1]], ['x', [2]]]], [2, [1, 2, 1]]], ['control: toffoli waits on all', [3, 0, [['h', [2]], ['h', [2]], ['ccx', [0, 1, 2]], ['x', [0]]]], [4, [4, 3, 3]]], ['control: cx waits on target', [2, 0, [['h', [1]], ['h', [1]], ['cx', [0, 1]]]], [3, [3, 3]]], ['control: identity is free', [1, 0, [['id', [0]], ['id', [0]], ['x', [0]]]], [1, [1]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: conditioned gate after measure', [2, 1, [['h', [0]], ['measure', [0], [0]], ['x', [1], 'if', 0]]], [3, [2, 3]]], ['control: measure after conditioned read', [2, 1, [['h', [0]], ['h', [0]], ['h', [0]], ['x', [1], 'if', 0], ['measure', [1], [0]]]], [3, [3, 2]]], ['control: empty circuit', [2, 1, []], [0, [0, 0]]], ['control: late read then early-qubit measure', [2, 1, [['h', [1]], ['h', [1]], ['h', [1]], ['x', [1], 'if', 0], ['measure', [0], [0]]]], [5, [5, 4]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: read then measure other clbit writer', [3, 2, [['h', [2]], ['h', [2]], ['z', [2], 'if', 1], ['measure', [0], [1]], ['x', [1], 'if', 1]]], [5, [4, 5, 3]]], ['control: random schedule 0', [1, 2, [['x', [0]], ['rz', [0]], ['measure', [0], [0]], ['x', [0]], ['barrier', [0]], ['x', [0], 'if', 1], ['x', [0], 'if', 1], ['x', [0]], ['measure', [0], [0]]]], [8, [8]]], ['control: random schedule 1', [4, 2, [['ccx', [1, 0, 3]], ['ccx', [2, 1, 3]], ['barrier', [0, 1, 2, 3]], ['cx', [1, 0]], ['id', [1]], ['cx', [1, 2]], ['cx', [0, 2]]]], [5, [5, 4, 5, 2]]], ['control: random schedule 2', [1, 1, [['h', [0]], ['rz', [0]], ['x', [0]], ['x', [0], 'if', 0], ['x', [0]], ['x', [0]], ['x', [0], 'if', 0], ['id', [0]]]], [7, [7]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: random schedule 3', [1, 2, [['h', [0]], ['h', [0]]]], [2, [2]]], ['control: random schedule 4', [4, 1, [['measure', [3], [0]], ['ccx', [2, 1, 0]], ['ccx', [0, 2, 3]]]], [2, [2, 1, 2, 2]]], ['control: random schedule 5', [3, 2, [['ccx', [0, 1, 2]], ['ccx', [2, 1, 0]], ['barrier', [0, 1, 2]], ['x', [1]]]], [3, [2, 3, 2]]], ['control: random schedule 6', [4, 2, [['barrier', [2]], ['cx', [1, 2]], ['ccx', [2, 3, 0]]]], [2, [2, 1, 2, 2]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: random schedule 7', [4, 2, [['x', [2], 'if', 1], ['x', [1]], ['barrier', [2]], ['cx', [0, 1]], ['h', [2]]]], [2, [2, 2, 2, 0]]], ['control: random schedule 8', [1, 1, [['x', [0], 'if', 0], ['rz', [0]], ['rz', [0]], ['h', [0]], ['rz', [0]], ['h', [0]], ['measure', [0], [0]], ['rz', [0]]]], [8, [8]]], ['control: random schedule 9', [3, 1, [['cx', [2, 1]], ['h', [1]], ['barrier', [1, 2]]]], [2, [0, 2, 2]]], ['control: random schedule 10', [4, 1, [['id', [2]]]], [0, [0, 0, 0, 0]]]]]
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 fixtureActualExpectedOutcome
regression: barrier aligns everything[2, [2, 0, 1]][3, [2, 2, 3]]Failed
regression: random schedule 37[4, [4, 0, 3]][4, [4, 3, 3]]Failed
regression: random schedule 47[4, [4, 4, 1, 3]][4, [4, 4, 2, 3]]Failed
control: partial barrier[2, [1, 2, 1]][2, [1, 2, 1]]Passed
control: toffoli waits on all[4, [4, 3, 3]][4, [4, 3, 3]]Passed
control: cx waits on target[3, [3, 3]][3, [3, 3]]Passed
control: identity is free[1, [1]][1, [1]]Passed

SHA-256 / d7a82f6e5a58fffb95d95e2a8192874493c905e9e4b0713bd9b2d9d7af5e9b68

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    nq, nc, ops = x
    ql = [0] * nq
    cl = [0] * nc
    for op in ops:
        name, qs = op[0], op[1]
        if name == 'barrier':
            qs = qs or list(range(nq))
            top = max(ql[q] for q in qs)
            for q in qs:
                ql[q] = top
            continue
        if name == 'id':
            continue
        cbits = []
        if name == 'measure':
            cbits = op[2]
        elif len(op) > 2 and op[2] == 'if':
            cbits = [op[3]]
        level = 1 + max([ql[q] for q in qs] + [cl[c] for c in cbits])
        for q in qs:
            ql[q] = level
        for c in cbits:
            cl[c] = level
    return [max(ql + cl + [0]), ql]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: partial barrier', [3, 1, [['h', [0]], ['barrier', [0, 1]], ['x', [1]], ['x', [2]]]], [2, [1, 2, 1]]], ['control: toffoli waits on all', [3, 0, [['h', [2]], ['h', [2]], ['ccx', [0, 1, 2]], ['x', [0]]]], [4, [4, 3, 3]]], ['control: cx waits on target', [2, 0, [['h', [1]], ['h', [1]], ['cx', [0, 1]]]], [3, [3, 3]]], ['control: identity is free', [1, 0, [['id', [0]], ['id', [0]], ['x', [0]]]], [1, [1]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: conditioned gate after measure', [2, 1, [['h', [0]], ['measure', [0], [0]], ['x', [1], 'if', 0]]], [3, [2, 3]]], ['control: measure after conditioned read', [2, 1, [['h', [0]], ['h', [0]], ['h', [0]], ['x', [1], 'if', 0], ['measure', [1], [0]]]], [3, [3, 2]]], ['control: empty circuit', [2, 1, []], [0, [0, 0]]], ['control: late read then early-qubit measure', [2, 1, [['h', [1]], ['h', [1]], ['h', [1]], ['x', [1], 'if', 0], ['measure', [0], [0]]]], [5, [5, 4]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: read then measure other clbit writer', [3, 2, [['h', [2]], ['h', [2]], ['z', [2], 'if', 1], ['measure', [0], [1]], ['x', [1], 'if', 1]]], [5, [4, 5, 3]]], ['control: random schedule 0', [1, 2, [['x', [0]], ['rz', [0]], ['measure', [0], [0]], ['x', [0]], ['barrier', [0]], ['x', [0], 'if', 1], ['x', [0], 'if', 1], ['x', [0]], ['measure', [0], [0]]]], [8, [8]]], ['control: random schedule 1', [4, 2, [['ccx', [1, 0, 3]], ['ccx', [2, 1, 3]], ['barrier', [0, 1, 2, 3]], ['cx', [1, 0]], ['id', [1]], ['cx', [1, 2]], ['cx', [0, 2]]]], [5, [5, 4, 5, 2]]], ['control: random schedule 2', [1, 1, [['h', [0]], ['rz', [0]], ['x', [0]], ['x', [0], 'if', 0], ['x', [0]], ['x', [0]], ['x', [0], 'if', 0], ['id', [0]]]], [7, [7]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: random schedule 3', [1, 2, [['h', [0]], ['h', [0]]]], [2, [2]]], ['control: random schedule 4', [4, 1, [['measure', [3], [0]], ['ccx', [2, 1, 0]], ['ccx', [0, 2, 3]]]], [2, [2, 1, 2, 2]]], ['control: random schedule 5', [3, 2, [['ccx', [0, 1, 2]], ['ccx', [2, 1, 0]], ['barrier', [0, 1, 2]], ['x', [1]]]], [3, [2, 3, 2]]], ['control: random schedule 6', [4, 2, [['barrier', [2]], ['cx', [1, 2]], ['ccx', [2, 3, 0]]]], [2, [2, 1, 2, 2]]]], [['regression: barrier aligns everything', [3, 1, [['h', [0]], ['h', [0]], ['barrier', []], ['x', [2]]]], [3, [2, 2, 3]]], ['regression: random schedule 37', [3, 2, [['rz', [2]], ['rz', [0]], ['h', [0]], ['h', [2]], ['rz', [2]], ['barrier', []], ['x', [0], 'if', 0]]], [4, [4, 3, 3]]], ['regression: random schedule 47', [4, 1, [['ccx', [1, 0, 3]], ['barrier', []], ['measure', [0], [0]], ['x', [3]], ['ccx', [1, 3, 0]], ['cx', [0, 1]], ['x', [2]], ['id', [0]]]], [4, [4, 4, 2, 3]]], ['control: random schedule 7', [4, 2, [['x', [2], 'if', 1], ['x', [1]], ['barrier', [2]], ['cx', [0, 1]], ['h', [2]]]], [2, [2, 2, 2, 0]]], ['control: random schedule 8', [1, 1, [['x', [0], 'if', 0], ['rz', [0]], ['rz', [0]], ['h', [0]], ['rz', [0]], ['h', [0]], ['measure', [0], [0]], ['rz', [0]]]], [8, [8]]], ['control: random schedule 9', [3, 1, [['cx', [2, 1]], ['h', [1]], ['barrier', [1, 2]]]], [2, [0, 2, 2]]], ['control: random schedule 10', [4, 1, [['id', [2]]]], [0, [0, 0, 0, 0]]]]]
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 fixtureActualExpectedOutcome
regression: barrier aligns everything[3, [2, 2, 3]][3, [2, 2, 3]]Passed
regression: random schedule 37[4, [4, 3, 3]][4, [4, 3, 3]]Passed
regression: random schedule 47[4, [4, 4, 2, 3]][4, [4, 4, 2, 3]]Passed
control: partial barrier[2, [1, 2, 1]][2, [1, 2, 1]]Passed
control: toffoli waits on all[4, [4, 3, 3]][4, [4, 3, 3]]Passed
control: cx waits on target[3, [3, 3]][3, [3, 3]]Passed
control: identity is free[1, [1]][1, [1]]Passed

SHA-256 / b5abadab18d3a46d1ea240a86a5b0dbb26c878a4bf8120850971cc1f4bf59795

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 2026-09-29T14:51:32.156937+00:00.

Case digest / 310911591c6df9e2f6e943b5aad9e71344d474e5a62d053c2b7be5d8eed19714