Support barriers in Aer simulators

docs/changelog.rst

@@ -1,6 +1,11 @@
 Changelog
 ~~~~~~~~~
 
+unreleased
+----------
+
+* Add support for circuits with barriers in the Aer simulators.
+
 0.45.0 (October 2023)
 ---------------------
 

pytket/extensions/qiskit/backends/aer.py

@@ -99,6 +99,9 @@ def _tket_gate_set_from_qiskit_backend(
         for gate_str in config.basis_gates
         if gate_str in _gate_str_2_optype
     }
+
+    gate_set.add(OpType.Barrier)
+
     if "unitary" in config.basis_gates:
         gate_set.add(OpType.Unitary1qBox)
         gate_set.add(OpType.Unitary2qBox)

tests/backend_test.py

@@ -79,7 +79,7 @@
     get_operator_expectation_value,
 )
 from pytket.utils.operators import QubitPauliOperator
-from pytket.utils.results import compare_statevectors
+from pytket.utils.results import compare_statevectors, compare_unitaries
 
 skip_remote_tests: bool = os.getenv("PYTKET_RUN_REMOTE_TESTS") is None
 
@@ -1403,3 +1403,29 @@ def test_unitary_backend_transpiles() -> None:
     # check that the lower-right 2x2 submatrix of the unitary is the matrix of
     # the X gate.
     assert np.isclose(u[62:64, 62:64], np.asarray(([0.0, 1.0], [1.0, 0.0]))).all()
+
+
+def test_barriers_in_aer_simulators() -> None:
+    """Test for barrier support in aer simulators
+    https://github.com/CQCL/pytket-qiskit/issues/186"""
+
+    circ = Circuit(2).H(0).CX(0, 1).add_barrier([0, 1])
+
+    state_backend = AerStateBackend()
+    shots_backend = AerBackend()
+    unitary_backend = AerUnitaryBackend()
+
+    test_state = circ.get_statevector()
+    test_unitary = circ.get_unitary()
+
+    backends = (state_backend, unitary_backend, shots_backend)
+
+    for backend in backends:
+        assert OpType.Barrier in backend.backend_info.gate_set
+        assert backend.valid_circuit(circ)
+
+    state_result = state_backend.run_circuit(circ).get_state()
+    unitary_result = unitary_backend.run_circuit(circ).get_unitary()
+
+    assert compare_statevectors(test_state, state_result)
+    assert compare_unitaries(test_unitary, unitary_result)