revert Isometry.inverse change in Qiskit#8231

qiskit/extensions/quantum_initializer/isometry.py

@@ -108,19 +108,12 @@ def _define(self):
         # TODO The inverse().inverse() is because there is code to uncompute (_gates_to_uncompute)
         #  an isometry, but not for generating its decomposition. It would be cheaper to do the
         #  later here instead.
-        gate = self.inv_gate()
-        gate = gate.inverse()
+        gate = self.inverse().inverse()
         q = QuantumRegister(self.num_qubits)
         iso_circuit = QuantumCircuit(q)
         iso_circuit.append(gate, q[:])
         self.definition = iso_circuit
 
-    def inverse(self):
-        self.params = []
-        inv = super().inverse()
-        self.params = [self.iso_data]
-        return inv
-
     def _gates_to_uncompute(self):
         """
         Call to create a circuit with gates that take the desired isometry to the first 2^m columns
@@ -313,7 +306,7 @@ def validate_parameter(self, parameter):
         else:
             raise CircuitError(f"invalid param type {type(parameter)} for gate {self.name}")
 
-    def inv_gate(self):
+    def inverse(self):
         """Return the adjoint of the unitary."""
         if self._inverse is None:
             # call to generate the circuit that takes the isometry to the first 2^m columns

releasenotes/notes/fix_multiplexer_transpiled_from_inverse_isometry-eea84f7f6d3a0310.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Revert change of :class:`.Isometry` in #8231. 
+    multiplexer instruction needs a matrix as its parameter. However,
+    the transpiler does not produce multiplexer with any parameters from
+    inverse-isometry instruction with #8231. This fix reverts a change related
+    to transpilation of multiplexer.

test/python/circuit/test_uc.py

@@ -85,6 +85,19 @@ def test_global_phase_ucg(self):
 
         self.assertTrue(np.allclose(unitary_desired, unitary))
 
+    def test_inverse_isometry_transpile(self):
+        """Test multiplexer transpiled from inverse isometry"""
+        qc = QuantumCircuit(1,1)
+        vector = [0.2, 0.1]
+        vector_circuit = QuantumCircuit(1)
+        vector_circuit.isometry(vector / np.linalg.norm(vector), [0], None)
+        vector_circuit = vector_circuit.inverse()
+        qc.append(vector_circuit, [0])
+
+        qc = transpile(qc, basis_gates=['multiplexer', 'measure'])
+
+        self.assertEqual(len(qc.data[0][0].params), 1)
+
 
 def _get_ucg_matrix(squs):
     return block_diag(*squs)