Transpilation fails with snapshot instruction #5556
Description
Information
- Qiskit Terra version: master
- Python version: 3.8.5
- Operating system: Linux
What is the current behavior?
Transpiling a simple circuit, which contains a snapshot, with basis gates ['u', 'cx'], raises an error. The same happens with more sets of basis gates: ['r', 'cz'], ['rz', 'rx', 'cz'], ['p', 'sx', 'cx']. However transpiling the same circuit with basis gates ['u3', 'cx'] is OK.
Note: this is working well with the stable version, the bug appears only in the master version.
Steps to reproduce the problem
from qiskit import QuantumCircuit, transpile
from qiskit.providers.aer import QasmSimulator
from qiskit.providers.aer.extensions import snapshot_statevector
backend = QasmSimulator()
circ = QuantumCircuit(1)
circ.z(0)
circ.snapshot_statevector('final')
transpile(circ, backend, basis_gates=['u3', 'cx'])
print("Transpilation with ['u3', 'cx'] is fine")
transpile(circ, backend, basis_gates=['u', 'cx'])
print("Transpilation with ['u', 'cx'] is fine")
results with
(YaelEnv) yaelbh@iris-quantum2:~/work/not_qiskit$ python snapshot_invalid.py
/home/yaelbh/work/terra/System/qiskit/__init__.py:69: RuntimeWarning: Could not import the IBMQ provider from the qiskit-ibmq-provider package. Install qiskit-ibmq-provider or check your installation.
warnings.warn('Could not import the IBMQ provider from the '
/opt/anaconda3/envs/YaelEnv/lib/python3.8/site-packages/qiskit/aqua/operators/operator_globals.py:48: DeprecationWarning: `from_label` is deprecated and will be removed no earlier than 3 months after the release date. Use Pauli(label) instead.
X = make_immutable(PrimitiveOp(Pauli.from_label('X')))
Transpilation with ['u3', 'cx'] is fine
Traceback (most recent call last):
File "snapshot_invalid.py", line 14, in <module>
transpile(circ, backend, basis_gates=['u', 'cx'])
File "/home/yaelbh/work/terra/System/qiskit/compiler/transpile.py", line 241, in transpile
circuits = parallel_map(_transpile_circuit, list(zip(circuits, transpile_args)))
File "/home/yaelbh/work/terra/System/qiskit/tools/parallel.py", line 112, in parallel_map
return [task(values[0], *task_args, **task_kwargs)]
File "/home/yaelbh/work/terra/System/qiskit/compiler/transpile.py", line 324, in _transpile_circuit
result = pass_manager.run(circuit, callback=transpile_config['callback'],
File "/home/yaelbh/work/terra/System/qiskit/transpiler/passmanager.py", line 225, in run
return self._run_single_circuit(circuits, output_name, callback)
File "/home/yaelbh/work/terra/System/qiskit/transpiler/passmanager.py", line 288, in _run_single_circuit
result = running_passmanager.run(circuit, output_name=output_name, callback=callback)
File "/home/yaelbh/work/terra/System/qiskit/transpiler/runningpassmanager.py", line 113, in run
dag = self._do_pass(pass_, dag, passset.options)
File "/home/yaelbh/work/terra/System/qiskit/transpiler/runningpassmanager.py", line 144, in _do_pass
dag = self._run_this_pass(pass_, dag)
File "/home/yaelbh/work/terra/System/qiskit/transpiler/runningpassmanager.py", line 156, in _run_this_pass
new_dag = pass_.run(dag)
File "/home/yaelbh/work/terra/System/qiskit/transpiler/passes/optimization/optimize_1q_decomposition.py", line 87, in run
operator = Operator(qc)
File "/home/yaelbh/work/terra/System/qiskit/quantum_info/operators/operator.py", line 85, in __init__
self._data = self._init_instruction(data).data
File "/home/yaelbh/work/terra/System/qiskit/quantum_info/operators/operator.py", line 496, in _init_instruction
op._append_instruction(instruction)
File "/home/yaelbh/work/terra/System/qiskit/quantum_info/operators/operator.py", line 554, in _append_instruction
self._append_instruction(instr, qargs=new_qargs)
File "/home/yaelbh/work/terra/System/qiskit/quantum_info/operators/operator.py", line 532, in _append_instruction
raise QiskitError('Cannot apply Instruction: {}'.format(obj.name))
qiskit.exceptions.QiskitError: 'Cannot apply Instruction: snapshot'