FA-91018 / Quantum circuit simulation / Member archive

Depth scheduler treats an empty barrier as a no-op · case 03

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

Member previewVariant 3 · 3 implementations · 7 checks per implementation

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.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: barrier aligns everything	`[2, [2, 0, 1]]`	`[3, [2, 2, 3]]`	Failed

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