Qiskit v0.18 updates

pennylane_qiskit/qiskit_device.py

@@ -59,23 +59,24 @@ def pauli_eigs(n):
     "PauliY": ex.YGate,
     "PauliZ": ex.ZGate,
     "Hadamard": ex.HGate,
-    "CNOT": ex.CnotGate,
-    "CZ": ex.CzGate,
+    "CNOT": ex.CXGate,
+    "CZ": ex.CZGate,
     "SWAP": ex.SwapGate,
     "RX": ex.RXGate,
     "RY": ex.RYGate,
     "RZ": ex.RZGate,
     "S": ex.SGate,
     "T": ex.TGate,
-
     # Adding the following for conversion compatibility
-    "CSWAP": ex.FredkinGate,
-    "CRZ": ex.CrzGate,
+    "CSWAP": ex.CSwapGate,
+    "CRX": ex.CRXGate,
+    "CRY": ex.CRYGate,
+    "CRZ": ex.CRZGate,
     "PhaseShift": ex.U1Gate,
     "QubitStateVector": ex.Initialize,
     "U2": ex.U2Gate,
     "U3": ex.U3Gate,
-    "Toffoli": ex.ToffoliGate,
+    "Toffoli": ex.CCXGate,
     "QubitUnitary": ex.UnitaryGate,
 }
 
@@ -117,9 +118,11 @@ class QiskitDevice(Device, abc.ABC):
     operations = set(_operation_map.keys())
     observables = {"PauliX", "PauliY", "PauliZ", "Identity", "Hadamard", "Hermitian"}
 
-    hw_analytic_warning_message = "The analytic calculation of expectations and variances "\
-                                  "is only supported on statevector backends, not on the {}. "\
-                                  "The obtained result is based on sampling."
+    hw_analytic_warning_message = (
+        "The analytic calculation of expectations and variances "
+        "is only supported on statevector backends, not on the {}. "
+        "The obtained result is based on sampling."
+    )
 
     _eigs = {}
 
@@ -192,13 +195,18 @@ def apply(self, operation, wires, par):
         if operation == "QubitStateVector":
 
             if self.backend_name == "unitary_simulator":
-                raise QuantumFunctionError("The QubitStateVector operation is not supported on the unitary simulator backend.")
+                raise QuantumFunctionError(
+                    "The QubitStateVector operation is not supported on the unitary simulator backend."
+                )
 
             if len(par[0]) != 2 ** len(wires):
                 raise ValueError("State vector must be of length 2**wires.")
 
             qregs = list(reversed(qregs))
 
+            # TODO: Once a fix is available in Qiskit-Aer, remove the following:
+            par = (x.tolist() for x in par if isinstance(x, np.ndarray))
+
         if operation == "QubitUnitary":
 
             if len(par[0]) != 2 ** len(wires):
@@ -305,7 +313,11 @@ def pre_measure(self):
         for e in self.obs_queue:
             # Add unitaries if a different expectation value is given
             # Exclude unitary_simulator as it does not support memory=True
-            if hasattr(e, "return_type") and e.return_type == Sample and self.backend_name != 'unitary_simulator':
+            if (
+                hasattr(e, "return_type")
+                and e.return_type == Sample
+                and self.backend_name != "unitary_simulator"
+            ):
                 self.memory = True  # make sure to return samples
 
             if isinstance(e.name, list):
@@ -333,9 +345,7 @@ def expval(self, observable, wires, par):
 
         if self.analytic:
             # Raise a warning if backend is a hardware simulator
-            warnings.warn(self.hw_analytic_warning_message.
-                          format(self.backend),
-                          UserWarning)
+            warnings.warn(self.hw_analytic_warning_message.format(self.backend), UserWarning)
 
         # estimate the ev
         return np.mean(self.sample(observable, wires, par))
@@ -349,9 +359,7 @@ def var(self, observable, wires, par):
 
         if self.analytic:
             # Raise a warning if backend is a hardware simulator
-            warnings.warn(self.hw_analytic_warning_message.
-                          format(self.backend),
-                          UserWarning)
+            warnings.warn(self.hw_analytic_warning_message.format(self.backend), UserWarning)
 
         return np.var(self.sample(observable, wires, par))
 

tests/test_converter.py

@@ -240,7 +240,8 @@ def test_invalid_parameter_expression(self, recorder):
                 quantum_circuit(params={theta: qml.variable.Variable(0), phi: qml.variable.Variable(1)})
 
     def test_extra_parameters_were_passed(self, recorder):
-        """Tests that loading raises an error when extra parameters were passed."""
+        """Tests that loading raises an error when extra parameters were
+        passed."""
 
         theta = Parameter('θ')
         phi = Parameter('φ')
@@ -253,23 +254,60 @@ def test_extra_parameters_were_passed(self, recorder):
             with recorder:
                 quantum_circuit(params={theta: 0.5, phi: 0.3})
 
-    def test_crz(self, recorder):
-        """Tests loading a circuit with the controlled-Z operation."""
+    @pytest.mark.parametrize("qiskit_operation, pennylane_name", [(QuantumCircuit.crx, "CRX"), (QuantumCircuit.crz, "CRZ")])
+    def test_controlled_rotations(self, qiskit_operation, pennylane_name, recorder):
+        """Tests loading a circuit with two qubit controlled rotations (except
+        for CRY)."""
 
         q2 = QuantumRegister(2)
         qc = QuantumCircuit(q2)
-        qc.crz(0.5, q2[0], q2[1])
+
+        qiskit_operation(qc, 0.5, q2[0], q2[1])
+
 
         quantum_circuit = load(qc)
 
         with recorder:
             quantum_circuit()
 
         assert len(recorder.queue) == 1
-        assert recorder.queue[0].name == 'CRZ'
+        assert recorder.queue[0].name == pennylane_name
         assert recorder.queue[0].params == [0.5]
         assert recorder.queue[0].wires == [0, 1]
 
+    def test_cry(self, recorder):
+        """Tests that the decomposition of the controlled-Y operation is being
+        loaded."""
+        # This test will be merged into the test_controlled_rotations test once
+        # the native CRY is used in Qiskit and not a set of instructions
+        # yielded from decomposition is being added
+
+        q2 = QuantumRegister(2)
+        qc = QuantumCircuit(q2)
+
+        qc.cry(0.5, q2[0], q2[1])
+
+        quantum_circuit = load(qc)
+
+        with recorder:
+            quantum_circuit()
+
+        assert len(recorder.queue) == 4
+        assert recorder.queue[0].name == "U3"
+        assert recorder.queue[0].params == [0.25, 0, 0]
+        assert recorder.queue[0].wires == [1]
+
+        assert recorder.queue[1].name == "CNOT"
+        assert recorder.queue[1].wires == [0, 1]
+
+        assert recorder.queue[2].name == "U3"
+        assert recorder.queue[2].params == [-0.25, 0, 0]
+        assert recorder.queue[2].wires == [1]
+
+        assert recorder.queue[3].name == "CNOT"
+        assert recorder.queue[3].wires == [0, 1]
+
+
     def test_one_qubit_operations_supported_by_pennylane(self, recorder):
         """Tests loading a circuit with the one-qubit operations supported by PennyLane."""
 
@@ -812,7 +850,7 @@ def test_qasm_from_file(self, tmpdir, recorder):
             .format('Barrier')
         assert record[1].message.args[0] == "pennylane_qiskit.converter: The {} instruction is not supported by" \
                                             " PennyLane, and has not been added to the template."\
-            .format('Cu1Gate')
+            .format('CU1Gate')
         assert record[7].message.args[0] == "pennylane_qiskit.converter: The {} instruction is not supported by" \
                                             " PennyLane, and has not been added to the template."\
             .format('Measure')