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Description
Describe the bug
If I update backend.basis_gates by removing a gate, the basis gates persists even if I renewed the backend.
I confirmed that qiskit-ibm-runtime 0.39.0 with use_fractional_gates=False renewed the basis gates, but use_fractional_gates=True or newer versions cause the issue.
Steps to reproduce
I expect the basis gates of backend renewed is same as that of original. But it happens only for 0.39.0 and use_fractional_gates=False.
from qiskit_ibm_runtime import QiskitRuntimeService, __version__
print(f"runtime_version={__version__}")
def test_remove(gate: str, fractional: bool):
print(f"\nRemove {gate} gate with use_fractional_gates={fractional}")
service = QiskitRuntimeService(name="demo-premium")
backend = service.backend("ibm_fez", use_fractional_gates=fractional)
print("original\t", backend.basis_gates)
backend.basis_gates.remove(gate)
print(f"{gate} removed\t", backend.basis_gates)
backend = service.backend("ibm_fez", use_fractional_gates=fractional)
print("backend renewed\t", backend.basis_gates)
test_remove("cz", False)
test_remove("cz", True)runtime_version=0.39.0
Remove cz gate with use_fractional_gates=False
original ['cz', 'id', 'rz', 'sx', 'x']
cz removed ['id', 'rz', 'sx', 'x']
backend renewed ['cz', 'id', 'rz', 'sx', 'x']
Remove cz gate with use_fractional_gates=True
original ['cz', 'id', 'rx', 'rz', 'rzz', 'sx', 'x']
cz removed ['id', 'rx', 'rz', 'rzz', 'sx', 'x']
backend renewed ['id', 'rx', 'rz', 'rzz', 'sx', 'x']
runtime_version=0.40.0
Remove cz gate with use_fractional_gates=False
original ['cz', 'id', 'rz', 'sx', 'x']
cz removed ['id', 'rz', 'sx', 'x']
backend renewed ['id', 'rz', 'sx', 'x']
Remove cz gate with use_fractional_gates=True
original ['cz', 'id', 'rx', 'rz', 'rzz', 'sx', 'x']
cz removed ['id', 'rx', 'rz', 'rzz', 'sx', 'x']
backend renewed ['id', 'rx', 'rz', 'rzz', 'sx', 'x']
runtime_version=0.41.0.dev4+g3a8d49cb
Remove cz gate with use_fractional_gates=False
original ['cz', 'id', 'rz', 'sx', 'x']
cz removed ['id', 'rz', 'sx', 'x']
backend renewed ['id', 'rz', 'sx', 'x']
Remove cz gate with use_fractional_gates=True
original ['cz', 'id', 'rx', 'rz', 'rzz', 'sx', 'x']
cz removed ['id', 'rx', 'rz', 'rzz', 'sx', 'x']
backend renewed ['id', 'rx', 'rz', 'rzz', 'sx', 'x']
Expected behavior
The basis gates should be renewed when the backend is renewed as same as 0.39.0 and use_fractional_gates=False.
Suggested solutions
Additional Information
- qiskit-ibm-runtime version: 0.39.0, 0.40.0, main g3a8d49cb
- Python version: 3.12.10
- Operating system: macOS 15.5