[WIP] Pass transpilation options (#108)

* WIP Pass transpilation options * WIP Pass transpilation options * WIP Pass transpilation options * WIP Pass transpilation options * WIP PassTranspilationOptions * WIP PassTranspilationOptions * WIP PassTranspilationOptions * WIP PassTranspilationOptions * WIP PassTranspilationOptions * WIP PassTranspilationOptions * Apply suggestions from code review Typos corrected. Co-authored-by: antalszava <[email protected]> * API Doc changes * CHANGELOG.md updated. Documentation sugessions incorporated. Co-authored-by: antalszava <[email protected]>
PennyLaneAI · Oct 24, 2020 · 7ba24ac · 7ba24ac
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -18,6 +18,9 @@ This release contains contributions from (in alphabetical order):
 
 ### Improvements
 
+* Qiskit devices are now allowed to pass transpilation options.
+  [(#108)](https://github.com/PennyLaneAI/pennylane-qiskit/pull/108)
+
 * The provided devices are now compatible with Qiskit 0.23.
   [(#112)](https://github.com/PennyLaneAI/pennylane-qiskit/pull/112)
 
@@ -35,7 +38,7 @@ This release contains contributions from (in alphabetical order):
 
 This release contains contributions from (in alphabetical order):
 
-Josh Izaac, Nathan Killoran, Antal Száva
+Josh Izaac, Nathan Killoran, Sagar Pahwa, Antal Száva
 
 ---
 

diff --git a/pennylane_qiskit/aer.py b/pennylane_qiskit/aer.py
@@ -25,9 +25,10 @@ class AerDevice(QiskitDevice):
     """A PennyLane device for the C++ Qiskit Aer simulator.
 
     Please refer to the `Qiskit documentation <https://qiskit.org/documentation/>`_ for
-    for further information to the noise model and backend options.
+    further information on the noise model, backend options and transpile options.
 
-    A range of :code:`backend_options` can be given as kwargs that will be passed to the simulator.
+    A range of :code:`backend_options` that will be passed to the simulator and
+    a range of transpile options can be given as kwargs.
 
     For more information on backends, please visit the
     `Aer provider documentation <https://qiskit.org/documentation/apidoc/aer_provider.html>`_.

diff --git a/pennylane_qiskit/basic_aer.py b/pennylane_qiskit/basic_aer.py
@@ -25,9 +25,10 @@ class BasicAerDevice(QiskitDevice):
     """A PennyLane device for the native Python Qiskit simulator.
 
     Please see the `Qiskit documentations <https://qiskit.org/documentation/>`_
-    for more details.
+    further information on the backend options and transpile options.
 
-    A range of :code:`backend_options` can be given in as kwargs that will be passed to the simulator.
+    A range of :code:`backend_options` that will be passed to the simulator and
+    a range of transpile options can be given as kwargs.
 
     For more information on backends, please visit the
     `Basic Aer provider documentation <https://qiskit.org/documentation/apidoc/providers_basicaer.html>`_.

diff --git a/pennylane_qiskit/qiskit_device.py b/pennylane_qiskit/qiskit_device.py
@@ -182,6 +182,9 @@ def __init__(self, wires, provider, backend, shots=1024, **kwargs):
 
             self.noise_model = kwargs.pop("noise_model")
 
+        # set transpile_args
+        self.set_transpile_args(**kwargs)
+
         # Get further arguments for run
         s = inspect.signature(b.run)
         self.run_args = {}
@@ -194,9 +197,16 @@ def __init__(self, wires, provider, backend, shots=1024, **kwargs):
             # BasicAer
             self.run_args["backend_options"] = kwargs
 
+    def set_transpile_args(self, **kwargs):
+        """The transpile argument setter."""
+        transpile_sig = inspect.signature(transpile).parameters
+        self.transpile_args = {arg: kwargs[arg] for arg in transpile_sig if arg in kwargs}
+        self.transpile_args.pop("circuits", None)
+        self.transpile_args.pop("backend", None)
+
     @property
     def backend(self):
-        """The Qiskit simulation backend object"""
+        """The Qiskit simulation backend object."""
         return self.provider.get_backend(self.backend_name)
 
     def reset(self):
@@ -296,11 +306,13 @@ def qubit_unitary_check(operation, par, wires):
                 )
 
     def compile(self):
-        """Compile the quantum circuit to target
-        the provided compile_backend. If compile_backend is None,
-        then the target is simply the backend."""
+        """Compile the quantum circuit to target the provided compile_backend.
+
+        If compile_backend is None, then the target is simply the
+        backend.
+        """
         compile_backend = self.compile_backend or self.backend
-        compiled_circuits = transpile(self._circuit, backend=compile_backend)
+        compiled_circuits = transpile(self._circuit, backend=compile_backend, **self.transpile_args)
 
         # Specify to have a memory for hw/hw simulators
         memory = str(compile_backend) not in self._state_backends

diff --git a/tests/conftest.py b/tests/conftest.py
@@ -72,8 +72,10 @@ def device(request, backend, shots, analytic):
     if backend not in state_backends and analytic == True:
         pytest.skip("Hardware simulators do not support analytic mode")
 
-    def _device(n):
-        return request.param(wires=n, backend=backend, shots=shots, analytic=analytic)
+    def _device(n, device_options=None):
+        if device_options is None:
+            device_options = {}
+        return request.param(wires=n, backend=backend, shots=shots, analytic=analytic, **device_options)
 
     return _device
 

diff --git a/tests/test_qiskit_device.py b/tests/test_qiskit_device.py
@@ -4,6 +4,17 @@
 import pennylane as qml
 from pennylane_qiskit import AerDevice
 
+test_transpile_options = [
+    {},
+    {'optimization_level':2},
+    {'optimization_level':2, 'seed_transpiler':22}
+]
+
+test_device_options = [
+    {},
+    {'optimization_level':3},
+    {'optimization_level':1}
+]
 
 class TestProbabilities:
     """Tests for the probability function"""
@@ -14,6 +25,27 @@ def test_probability_no_results(self):
         dev = AerDevice(backend="statevector_simulator", wires=1, analytic=True)
         assert dev.probability() is None
 
+@pytest.mark.parametrize("analytic", [True])
+@pytest.mark.parametrize("wires", [1,2,3])
+@pytest.mark.parametrize("shots", [2])
+@pytest.mark.parametrize("device_options", test_device_options)
+@pytest.mark.transpile_args_test
+class TestTranspilationOptionInitialization:
+    """Tests for passing the transpilation options to qiskit at time of device 
+    initialization."""
+
+    def test_device_with_transpilation_options(self, device, wires, device_options):
+        """Test that the transpilation options must be persisted if provided."""
+        dev = device(wires, device_options)
+        assert dev.transpile_args == device_options
+
+    @pytest.mark.parametrize("transpile_options", test_transpile_options)
+    def test_transpilation_option_update(self, device, wires, device_options, transpile_options):
+        """Test that the transpilation options are updated as expected."""
+        dev = device(wires, device_options)
+        assert dev.transpile_args == device_options
+        dev.set_transpile_args(**transpile_options)
+        assert dev.transpile_args == transpile_options
 
 class TestAnalyticWarningHWSimulator:
     """Tests the warnings for when the analytic attribute of a device is set to true"""