LintQ Detector Evaluation Report

from qiskit import QuantumCircuit

# OpAfterMeas: a gate acts on a qubit after that qubit was measured,
# with no reset between along the CFG path.
qc = QuantumCircuit(2, 2)
qc.reset(0)
qc.reset(1)
qc.h(0)
qc.cx(0, 1)
qc.measure(0, 0)
qc.h(0)          # BUG: gate on q0 after measure(0) -> OpAfterMeas

from qiskit import QuantumCircuit

# NEGATIVE for OpAfterMeas: a reset lies between the measure and the later
# gate, so the gate does NOT operate on a post-measurement qubit state.
# A correct (reset-aware) detector must stay silent; a reset-blind detector
# (Engine A) will falsely fire here -- a documented limitation.
qc = QuantumCircuit(2, 2)
qc.reset(0)
qc.reset(1)
qc.h(0)
qc.measure(0, 0)
qc.reset(0)
qc.h(0)          # SAFE: reset(0) between measure(0) and this gate

from qiskit import QuantumCircuit

# OpAfterMeas via a 2-qubit gate: cx(0,1) touches BOTH q0 and q1, but only
# q1 was measured earlier. The detector must flag the gate on q1 (the
# measured qubit) and NOT on q0 (which was never measured).
qc = QuantumCircuit(2, 2)
qc.reset(0)
qc.reset(1)
qc.h(0)
qc.measure(1, 1)
qc.cx(0, 1)      # BUG on q1: 2-qubit gate acts on measured qubit q1

from qiskit import QuantumCircuit

# DoubleMeas: qubit q0 is measured twice with no operation on q0 between.
qc = QuantumCircuit(2, 2)
qc.reset(0)
qc.reset(1)
qc.h(0)
qc.measure(0, 0)
qc.measure(0, 0)    # BUG: redundant consecutive measure of q0

from qiskit import QuantumCircuit

# NEGATIVE for DoubleMeas: a reset on q0 sits between the two measures,
# so the second measure is NOT redundant. Both engines must stay silent.
qc = QuantumCircuit(2, 2)
qc.reset(0)
qc.reset(1)
qc.measure(0, 0)
qc.reset(0)         # op on q0 between the two measures -> breaks DoubleMeas
qc.measure(0, 0)    # SAFE: reset(0) between the two measures of q0

from qiskit import QuantumCircuit

# COMBINED / cross-detector: a 2-qubit gate cx(0,1) on q0 between two
# measures of q0 correctly SUPPRESSES DoubleMeas (an op touches q0 between),
# yet the same cx is a gate on q0 applied after the first measure, so it
# TRIGGERS OpAfterMeas. Demonstrates that one detector fires while the other
# must not.
qc = QuantumCircuit(2, 2)
qc.reset(0)
qc.reset(1)
qc.measure(0, 0)
qc.cx(0, 1)        # gate on q0 between measures -> suppresses DoubleMeas,
                   # but is itself a gate after measure -> OpAfterMeas on q0
qc.measure(0, 0)

from qiskit import QuantumCircuit

# MissingReset: the first operation that touches q0 is a gate (h), not a
# reset, so q0 is used while uninitialised. Engine B only.
qc = QuantumCircuit(2, 2)
qc.h(0)            # BUG: first op on q0 is h, not reset (MissingReset q0)
qc.measure(0, 0)

from qiskit import QuantumCircuit

# MissingReset via a 2-qubit gate: cx(0,1) is the first operation touching
# both q0 and q1, so both are used while uninitialised. Engine B must flag
# q0 and q1 (the cx is a gate, not a reset).
qc = QuantumCircuit(2, 2)
qc.cx(0, 1)        # BUG: cx uses q0 and q1 before any reset (MissingReset q0, q1)

from qiskit import QuantumCircuit

# GhostCompose: qc.compose(sub) is non-mutating in Qiskit, but its return
# value is discarded, so the composed circuit is silently dropped. Engine A
# only.
qc = QuantumCircuit(1, 1)
sub = QuantumCircuit(1, 1)
sub.h(0)
qc.compose(sub)    # BUG: compose() return value discarded (GhostCompose)

from qiskit import QuantumCircuit

# NEGATIVE for GhostCompose: the result of compose() is captured in qc2, so
# the circuit is intentionally kept. The detector must NOT fire.
qc = QuantumCircuit(1, 1)
sub = QuantumCircuit(1, 1)
sub.h(0)
qc2 = qc.compose(sub)    # SAFE: return value captured -> no GhostCompose