Fix typing of inserted UnitaryGates in quantum_volume (#13479) (#13481)

There was a small typing issue in the quantum_volume implementation
where there was a mismatch in the Python type and the rust type. The
UnitaryGate were being added to the circuit as a rust space
PyInstruction instead of a PyGate. This was incorrect as UnitaryGate is
unitary and a gate type in python, this mismatch was causing subsequent
transpilation or anything working with the unitaries in the quantum
volume circuit from rust to mischaracterize the operations as
non-unitary so things like getting the matrix would fail. This commit
corrects the typing so the gates are added as a unitary operation in the
rust typing.

This will get much simpler and less error prone when #13272 is
implemented and we have a rust native UnitaryGate type.

(cherry picked from commit 4bb1432)

Co-authored-by: Matthew Treinish <[email protected]>

crates/accelerate/src/circuit_library/quantum_volume.rs

@@ -27,7 +27,7 @@ use rayon::prelude::*;
 use qiskit_circuit::circuit_data::CircuitData;
 use qiskit_circuit::imports::UNITARY_GATE;
 use qiskit_circuit::operations::Param;
-use qiskit_circuit::operations::PyInstruction;
+use qiskit_circuit::operations::PyGate;
 use qiskit_circuit::packed_instruction::PackedOperation;
 use qiskit_circuit::{Clbit, Qubit};
 use smallvec::{smallvec, SmallVec};
@@ -127,17 +127,16 @@ pub fn quantum_volume(
         let unitary_gate = UNITARY_GATE
             .get_bound(py)
             .call((unitary.clone(), py.None(), false), Some(&kwargs))?;
-        let instruction = PyInstruction {
+        let instruction = PyGate {
             qubits: 2,
             clbits: 0,
             params: 1,
             op_name: "unitary".to_string(),
-            control_flow: false,
-            instruction: unitary_gate.unbind(),
+            gate: unitary_gate.unbind(),
         };
         let qubit = layer_index * 2;
         Ok((
-            PackedOperation::from_instruction(Box::new(instruction)),
+            PackedOperation::from_gate(Box::new(instruction)),
             smallvec![Param::Obj(unitary.unbind().into())],
             vec![permutation[qubit], permutation[qubit + 1]],
             vec![],

test/python/transpiler/test_preset_passmanagers.py

@@ -22,6 +22,7 @@
 
 from qiskit import QuantumCircuit, ClassicalRegister, QuantumRegister
 from qiskit.circuit import Qubit, Gate, ControlFlowOp, ForLoopOp
+from qiskit.circuit.library import quantum_volume
 from qiskit.compiler import transpile
 from qiskit.transpiler import CouplingMap, Layout, PassManager, TranspilerError, Target
 from qiskit.circuit.library import U2Gate, U3Gate, QuantumVolume, CXGate, CZGate, XGate
@@ -343,6 +344,24 @@ def test_v1(self, circuit, level, backend):
             )
         self.assertIsInstance(result, QuantumCircuit)
 
+    @data(0, 1, 2, 3)
+    def test_quantum_volume_function_transpile(self, opt_level):
+        """Test quantum_volume transpilation."""
+        qc = quantum_volume(10, 10, 12345)
+        backend = GenericBackendV2(
+            num_qubits=100,
+            basis_gates=["cz", "rz", "sx", "x", "id"],
+            coupling_map=CouplingMap.from_grid(10, 10),
+        )
+        pm = generate_preset_pass_manager(opt_level, backend)
+        res = pm.run(qc)
+        for inst in res.data:
+            self.assertTrue(
+                backend.target.instruction_supported(
+                    inst.operation.name, qargs=tuple(res.find_bit(x).index for x in inst.qubits)
+                )
+            )
+
 
 @ddt
 class TestPassesInspection(QiskitTestCase):