Fix non-complex dtypes in OneQubitEulerDecomposer methods

qiskit/quantum_info/synthesis/one_qubit_decompose.py

@@ -252,6 +252,7 @@ def angles(self, unitary):
         Returns:
             tuple: (theta, phi, lambda).
         """
+        unitary = np.asarray(unitary, dtype=complex)
         theta, phi, lam, _ = self._params(unitary)
         return theta, phi, lam
 
@@ -264,6 +265,7 @@ def angles_and_phase(self, unitary):
         Returns:
             tuple: (theta, phi, lambda, phase).
         """
+        unitary = np.asarray(unitary, dtype=complex)
         return self._params(unitary)
 
     _params_zyz = staticmethod(euler_one_qubit_decomposer.params_zyz)

releasenotes/notes/fix-type-angles-euler-decompose-233e5cee7205ed03.yaml

@@ -0,0 +1,10 @@
+---
+fixes:
+  - |
+    Fixed an issue with the :class:`~.OneQubitEulerDecomposer` class's methods
+    :meth:`~.OneQubitEulerDecomposer.angles` and :meth:`~.OneQubitEulerDecomposer.angles_and_phase`
+    would error if the input matrix was of a dtype other than ``complex``/``np.cdouble``. In earlier
+    releases this worked fine but this stopped working in Qiskit Terra 0.23.0
+    when the internals of :class:`~.OneQubitEulerDecomposer` were re-written
+    in Rust.
+    Fixed `#9827 <https://github.com/Qiskit/qiskit-terra/issues/9827>`__

test/python/quantum_info/test_synthesis.py

@@ -591,6 +591,44 @@ def test_psx_zsx_special_cases(self):
             self.assertTrue(np.allclose(unitary, Operator(qc_zsx).data))
             self.assertTrue(np.allclose(unitary, Operator(qc_zsxx).data))
 
+    def test_float_input_angles_and_phase(self):
+        """Test angles and phase with float input."""
+        decomposer = OneQubitEulerDecomposer("PSX")
+        input_matrix = np.array(
+            [
+                [0.70710678, 0.70710678],
+                [0.70710678, -0.70710678],
+            ],
+            dtype=np.float64,
+        )
+        (theta, phi, lam, gamma) = decomposer.angles_and_phase(input_matrix)
+        expected_theta = 1.5707963267948966
+        expected_phi = 0.0
+        expected_lam = 3.141592653589793
+        expected_gamma = -0.7853981633974483
+        self.assertAlmostEqual(theta, expected_theta)
+        self.assertAlmostEqual(phi, expected_phi)
+        self.assertAlmostEqual(lam, expected_lam)
+        self.assertAlmostEqual(gamma, expected_gamma)
+
+    def test_float_input_angles(self):
+        """Test angles with float input."""
+        decomposer = OneQubitEulerDecomposer("PSX")
+        input_matrix = np.array(
+            [
+                [0.70710678, 0.70710678],
+                [0.70710678, -0.70710678],
+            ],
+            dtype=np.float64,
+        )
+        (theta, phi, lam) = decomposer.angles(input_matrix)
+        expected_theta = 1.5707963267948966
+        expected_phi = 0.0
+        expected_lam = 3.141592653589793
+        self.assertAlmostEqual(theta, expected_theta)
+        self.assertAlmostEqual(phi, expected_phi)
+        self.assertAlmostEqual(lam, expected_lam)
+
 
 # FIXME: streamline the set of test cases
 class TestTwoQubitWeylDecomposition(CheckDecompositions):