Fix opflow bugs (qiskit-community/qiskit-aqua#1390)

* fix qiskit-community/qiskit-aqua#1311

* fix qiskit-community/qiskit-aqua#1317

* add a test of reps for trotterization

* fix tests for qiskit-community/qiskit-aqua#1311

* fix typing

* fix qiskit-community/qiskit-aqua#1321

* add release note

* fix qiskit-community/qiskit-aqua#1381

* add a test for to_opflow

* Update qiskit/aqua/operators/converters/circuit_sampler.py

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>

* remove None from constructor

* simplify logic

* Revert "remove None from constructor"

This reverts commit c884ebba123adee22f252e11f90964a6defaec38.

* add releasenote

* simplify logic (not iscomplex to isreal)

* remove Optional

* Update qiskit/aqua/operators/legacy/weighted_pauli_operator.py

* Update qiskit/aqua/operators/legacy/weighted_pauli_operator.py

* Update qiskit/aqua/operators/legacy/weighted_pauli_operator.py

Co-authored-by: John Lapeyre <jlapeyre@users.noreply.github.com>
Co-authored-by: Panagiotis Barkoutsos <bpa@zurich.ibm.com>
Co-authored-by: Steve Wood <40241007+woodsp-ibm@users.noreply.github.com>

test/aqua/operators/legacy/test_weighted_pauli_operator.py

@@ -25,6 +25,7 @@
 from qiskit.aqua.operators import WeightedPauliOperator
 from qiskit.aqua.operators.legacy import op_converter
 from qiskit.aqua.components.initial_states import Custom
+from qiskit.aqua.operators import I, X, Y, Z
 
 
 @ddt
@@ -610,6 +611,22 @@ def eval_op(op):
         expectation_value, _ = eval_op(wpo2)
         self.assertAlmostEqual(expectation_value, -3.0, places=2)
 
+    def test_to_opflow(self):
+        """Test for to_opflow() in WeightedPauliOperator"""
+        pauli_a = 'IXYZ'
+        pauli_b = 'ZYIX'
+        coeff_a = 0.5 + 1j
+        coeff_b = -0.5 - 1j
+        pauli_term_a = [coeff_a, Pauli.from_label(pauli_a)]
+        pauli_term_b = [coeff_b, Pauli.from_label(pauli_b)]
+        op_a = WeightedPauliOperator(paulis=[pauli_term_a])
+        op_b = WeightedPauliOperator(paulis=[pauli_term_b])
+        legacy_op = op_a + op_b
+
+        op = coeff_a * (I ^ X ^ Y ^ Z) + coeff_b * (Z ^ Y ^ I ^ X)
+
+        self.assertEqual(op, legacy_op.to_opflow())
+
 
 if __name__ == '__main__':
     unittest.main()

test/aqua/operators/test_evolution.py

@@ -22,11 +22,11 @@
 from qiskit.circuit import ParameterVector, Parameter
 
 from qiskit.aqua.operators import (X, Y, Z, I, CX, H, ListOp, CircuitOp, Zero, EvolutionFactory,
-                                   EvolvedOp, PauliTrotterEvolution, QDrift)
-
+                                   EvolvedOp, PauliTrotterEvolution, QDrift, Trotter, Suzuki)
 
 # pylint: disable=invalid-name
 
+
 class TestEvolution(QiskitAquaTestCase):
     """Evolution tests."""
 
@@ -255,6 +255,20 @@ def test_mixed_evolution(self):
         for p in thetas[1:]:
             self.assertNotIn(p, circuit_params)
 
+    def test_reps(self):
+        """Test reps and order params in Trotterization"""
+        reps = 7
+        trotter = Trotter(reps=reps)
+        self.assertEqual(trotter.reps, reps)
+
+        order = 5
+        suzuki = Suzuki(reps=reps, order=order)
+        self.assertEqual(suzuki.reps, reps)
+        self.assertEqual(suzuki.order, order)
+
+        qdrift = QDrift(reps=reps)
+        self.assertEqual(qdrift.reps, reps)
+
 
 if __name__ == '__main__':
     unittest.main()

test/aqua/operators/test_state_construction.py

@@ -146,10 +146,10 @@ def test_circuit_state_fn_from_complex_vector_initialize(self):
 
     def test_sampling(self):
         """ state fn circuit from dict initialize test """
-        statedict = {'101': .5,
-                     '100': .1,
-                     '000': .2,
-                     '111': .5}
+        statedict = {'101': .5 + 1.j,
+                     '100': .1 + 2.j,
+                     '000': .2 + 0.j,
+                     '111': .5 + 1.j}
         sfc = CircuitStateFn.from_dict(statedict)
         circ_samples = sfc.sample()
         dict_samples = StateFn(statedict).sample()