GateDirection pass goes outside allowed basis gates #10785
Description
Environment
- Qiskit Terra version: 0.25
- Python version: 3.9
- Operating system: MacOS
What is happening?
Trying to run a clifford simulation on a fake backend with ECR basis gates leads to transpilation errors with unsupported basis gates
How can we reproduce the issue?
from qiskit import QuantumCircuit, transpile
from qiskit_aer import AerSimulator
from qiskit.providers.fake_provider import FakeSherbrooke, FakeWashington
# Stabilizer simulator for FakeSherbrooke
clifford_basis_gates = ['ecr', 'sx', 'x', 'id', 'z', 's', 'sdg']
backend = AerSimulator.from_backend(
FakeSherbrooke(),
method="stabilizer",
basis_gates=clifford_basis_gates,
)
# Circuit
qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
# Transpile
transpile(qc, backend)Raises
TranspilerError: "Unable to translate the operations in the circuit: ['ry', 'h', 'sdg', 'sx', 's', 'ecr', 'x'] to the backend's (or manually specified) target basis: ['break_loop', 'quantum_channel', 's', 'save_expval_var', 'for_loop', 'roerror', 'continue_loop', 'save_probabilities', 'z', 'qerror_loc', 'reset', 'save_clifford', 'snapshot', 'if_else', 'id', 'save_probabilities_dict', 'ecr', 'save_state', 'save_amplitudes_sq', 'sdg', 'save_stabilizer', 'delay', 'while_loop', 'save_expval', 'set_stabilizer', 'sx', 'measure', 'barrier', 'x']. This likely means the target basis is not universal or there are additional equivalence rules needed in the EquivalenceLibrary being used. For more details on this error see: https://qiskit.org/documentation/stubs/qiskit.transpiler.passes.BasisTranslator.html#translation_errors"
What should happen?
Running with a manually specified basis gates works (though the output is not at all optimized in terms of number of 1Q gates):
transpile(qc, basis_gates=["ecr", "x", "sx", "id", "z", "s", "sdg"])global phase: 3π/2
┌───┐┌────┐┌───┐ ┌─────┐ ┌──────┐┌───┐
q_0: ┤ S ├┤ √X ├┤ S ├─┤ Sdg ├─────┤0 ├┤ X ├
├───┤├───┬┘├───┴┐└┬───┬┘┌───┐│ Ecr │└───┘
q_1: ┤ S ├┤ S ├─┤ √X ├─┤ S ├─┤ S ├┤1 ├─────
└───┘└───┘ └────┘ └───┘ └───┘└──────┘
Any suggestions?
Running transpilation with a callback looks like the issues is due to the GateDirection pass which inserts non-Clifford gates outside the allowed basis gates into the circuit and causes the rest of the transpilation to fail.
def callback(**kwargs):
print(f"{type(kwargs['pass_']).__name__} output gates: {kwargs['dag'].count_ops()}")
transpile(qc, backend, callback=callback).draw()ContainsInstruction, gates: {'h': 1, 'cx': 1}
UnitarySynthesis, gates: {'h': 1, 'cx': 1}
HighLevelSynthesis, gates: {'h': 1, 'cx': 1}
Unroll3qOrMore, gates: {'h': 1, 'cx': 1}
SetLayout, gates: {'h': 1, 'cx': 1}
TrivialLayout, gates: {'h': 1, 'cx': 1}
CheckMap, gates: {'h': 1, 'cx': 1}
FullAncillaAllocation, gates: {'h': 1, 'cx': 1}
EnlargeWithAncilla, gates: {'h': 1, 'cx': 1}
ApplyLayout, gates: {'h': 1, 'cx': 1}
CheckMap, gates: {'h': 1, 'cx': 1}
UnitarySynthesis, gates: {'h': 1, 'cx': 1}
HighLevelSynthesis, gates: {'h': 1, 'cx': 1}
UnrollCustomDefinitions, gates: {'h': 1, 'cx': 1}
BasisTranslator, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'ecr': 1, 'x': 1}
CheckGateDirection, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'ecr': 1, 'x': 1}
GateDirection, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2} # NON BASIS RY INSERTED HERE
RemoveResetInZeroState, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
Depth, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
FixedPoint, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
Size, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
FixedPoint, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
Optimize1qGatesDecomposition, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
CXCancellation, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
GatesInBasis, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
UnitarySynthesis, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
HighLevelSynthesis, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
UnrollCustomDefinitions, gates: {'s': 6, 'sx': 2, 'sdg': 1, 'x': 1, 'ry': 2, 'ecr': 1, 'h': 2}
# raises exception here
This pass should only insert gates supported by the backend, and be updated to work with Clifford basis backends to enable simulation testing