fix sub_dims bug in _get_iq_data (#297)

qiskit-community · Jan 12, 2024 · d1cf278 · d1cf278
1 parent 27a804a
commit d1cf278
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Showing 2 changed files with 20 additions and 3 deletions.
diff --git a/qiskit_dynamics/backend/backend_utils.py b/qiskit_dynamics/backend/backend_utils.py
@@ -234,7 +234,7 @@ def _get_iq_data(
         QiskitError: If number of centers and levels don't match.
     """
     rng = np.random.default_rng(seed)
-    subsystem_dims = state.dims()
+    subsystem_dims = [dim for dim in state.dims() if dim != 1]
     probabilities = state.probabilities()
     probabilities_tensor = probabilities.reshape(list(reversed(subsystem_dims)))
 

diff --git a/test/dynamics/backend/test_backend_utils.py b/test/dynamics/backend/test_backend_utils.py
@@ -281,7 +281,7 @@ def test_basic_predict(self):
         self.assertDictEqual(counts, {"0": 100})
 
     def test_multi_qubit_predict(self):
-        """Multi_qubit predict test case."""
+        """Multi qubit predict test case."""
         iq_data = _get_iq_data(
             state=Statevector(np.array([0.5, 1, 0, 0]) / np.sqrt(1.25)),
             measurement_subsystems=[0, 1],
@@ -297,8 +297,25 @@ def test_multi_qubit_predict(self):
         self.assertDictEqual(counts0, {"0": 74, "1": 26})
         self.assertDictEqual(counts1, {"1": 100})
 
+    def test_multi_qubit_with_1d_subsystem(self):
+        """Multi qubit with 1d (trivial) subsystems."""
+        iq_data = _get_iq_data(
+            state=Statevector(np.array([0.5, 1, 0, 0]) / np.sqrt(1.25), dims=(1, 1, 2, 2, 1, 1)),
+            measurement_subsystems=[0, 1],
+            iq_centers=[[(1, 0), (-1, 0)], [(1, 0), (-1, 0)]],
+            iq_width=0.1,
+            shots=100,
+            memory_slot_indices=[0, 1],
+            seed=83248,
+        )
+
+        counts0 = self.iq_to_counts(iq_data[:, 0, :])
+        counts1 = self.iq_to_counts(iq_data[:, 1, :])
+        self.assertDictEqual(counts0, {"0": 74, "1": 26})
+        self.assertDictEqual(counts1, {"1": 100})
+
     def test_mixed_subsystem_predict(self):
-        """Multi_qubit predict test case."""
+        """Multi qubit predict test case."""
         iq_data = _get_iq_data(
             state=Statevector(
                 np.kron(np.array([0.5, 1]), np.array([0, 0, 1])) / np.sqrt(1.25), dims=(3, 2)