Fix add_gate behavior when supplied multiple indices (#142)

qutip · May 12, 2022 · 2fb741a · 2fb741a
1 parent 38861aa
commit 2fb741a
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Showing 2 changed files with 52 additions and 7 deletions.
diff --git a/src/qutip_qip/circuit.py b/src/qutip_qip/circuit.py
@@ -343,7 +343,8 @@ def add_gate(
         arg_label: string
             Label for gate representation.
         index : list
-            Positions to add the gate.
+            Positions to add the gate. Each index in the supplied list refers
+            to a position in the original list of gates.
         classical_controls : int or list of int, optional
             indices of classical bits to control gate on.
         control_value : int, optional
@@ -378,7 +379,10 @@ def add_gate(
             self.gates.append(gate)
 
         else:
-            for position in index:
+            # NOTE: Every insertion shifts the indices in the original list of
+            #       gates by an additional position to the right.
+            shifted_inds = np.sort(index) + np.arange(len(index))
+            for position in shifted_inds:
                 gate = Gate(
                     name,
                     targets=targets,

diff --git a/tests/test_circuit.py b/tests/test_circuit.py
@@ -230,6 +230,52 @@ def test_add_gate(self):
             # Single control
             pytest.raises(ValueError, qc.add_gate, gate, [0], [1])
 
+        dummy_gate1 = Gate("DUMMY1")
+        inds = [1, 3, 4, 6]
+        qc.add_gate(dummy_gate1, index=inds)
+
+        # Test adding gates at multiple (sorted) indices at once.
+        # NOTE: Every insertion shifts the indices in the original list of
+        #       gates by an additional position to the right.
+        expected_gate_names = [
+            'CNOT',     # 0
+            'DUMMY1',   # 1
+            'SWAP',     # 2
+            'TOFFOLI',  # 3
+            'DUMMY1',   # 4
+            'SWAP',     # 5
+            'DUMMY1',   # 6
+            'SNOT',     # 7
+            'RY',       # 8
+            'DUMMY1',   # 9
+            'RY',       # 10
+        ]
+        actual_gate_names = [gate.name for gate in qc.gates]
+        assert actual_gate_names == expected_gate_names
+
+        dummy_gate2 = Gate("DUMMY2")
+        inds = [11, 0]
+        qc.add_gate(dummy_gate2, index=inds)
+
+        # Test adding gates at multiple (unsorted) indices at once.
+        expected_gate_names = [
+            'DUMMY2',   # 0
+            'CNOT',     # 1
+            'DUMMY1',   # 2
+            'SWAP',     # 3
+            'TOFFOLI',  # 4
+            'DUMMY1',   # 5
+            'SWAP',     # 6
+            'DUMMY1',   # 7
+            'SNOT',     # 8
+            'RY',       # 9
+            'DUMMY1',   # 10
+            'RY',       # 11
+            'DUMMY2',   # 12
+        ]
+        actual_gate_names = [gate.name for gate in qc.gates]
+        assert actual_gate_names == expected_gate_names
+
     def test_add_circuit(self):
         """
         Addition of a circuit to a `QubitCircuit`
@@ -522,7 +568,6 @@ def test_run_teleportation(self):
 
         teleportation_sim_results = teleportation_sim.run(state)
         state_final = teleportation_sim_results.get_final_states(0)
-        probability = teleportation_sim_results.get_probabilities(0)
 
         final_measurement = Measurement("start", targets=[2])
         _, final_probabilities = final_measurement.measurement_comp_basis(state_final)
@@ -611,10 +656,6 @@ def test_wstate(self):
         qc = read_qasm(filepath)
 
         rand_state = rand_ket(2)
-        wstate = (tensor(basis(2, 0), basis(2, 0), basis(2, 1))
-                  + tensor(basis(2, 0), basis(2, 1), basis(2, 0))
-                  + tensor(basis(2, 1), basis(2, 0), basis(2, 0))).unit()
-
         state = tensor(tensor(basis(2, 0), basis(2, 0), basis(2, 0)),
                        rand_state)