Compile any QuantumWorld to qubits (#76)

* Add the option to compile the quantum world to qubits.

* Unify ancilla and compiled qubits logic. Add tests.

* More tests

* Reformat with black

* TicTacToe, more tests and reformatting

* Refactor

* Address comments, add more tests

* Support qudit operations in SparseSimulator via compilation

* Add comment for compiled_qubits dict

* Appease lint checker for Windows

unitary/alpha/quantum_effect.py

@@ -49,7 +49,7 @@ def _verify_objects(self, *objects):
                 q.num_states != required_dimension
             ):
                 raise ValueError(
-                    f"Cannot apply effect to qids of dimension {required_dimension}."
+                    f"Cannot apply effect to qids of dimension {q.num_states}."
                 )
             if q.world is None:
                 raise ValueError(

unitary/alpha/quantum_effect_test.py

@@ -23,9 +23,10 @@
 Q1 = cirq.NamedQubit("q1")
 
 
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
 @pytest.mark.parametrize("simulator", [cirq.Simulator, SparseSimulator])
-def test_quantum_if(simulator):
-    board = alpha.QuantumWorld(sampler=simulator())
+def test_quantum_if(simulator, compile_to_qubits):
+    board = alpha.QuantumWorld(sampler=simulator(), compile_to_qubits=compile_to_qubits)
     piece = alpha.QuantumObject("q0", 1)
     piece2 = alpha.QuantumObject("q1", 0)
     board.add_object(piece)
@@ -44,9 +45,10 @@ def test_quantum_if(simulator):
     assert (result[1] == 1 for result in results)
 
 
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
 @pytest.mark.parametrize("simulator", [cirq.Simulator, SparseSimulator])
-def test_anti_control(simulator):
-    board = alpha.QuantumWorld(sampler=simulator())
+def test_anti_control(simulator, compile_to_qubits):
+    board = alpha.QuantumWorld(sampler=simulator(), compile_to_qubits=compile_to_qubits)
     piece = alpha.QuantumObject("q0", 0)
     piece2 = alpha.QuantumObject("q1", 0)
     board.add_object(piece)
@@ -72,8 +74,9 @@ def test_no_world():
         alpha.Flip()(piece)
 
 
-def test_bad_length():
-    board = alpha.QuantumWorld()
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
+def test_bad_length(compile_to_qubits):
+    board = alpha.QuantumWorld(compile_to_qubits=compile_to_qubits)
     piece = alpha.QuantumObject("q0", 1)
     board.add_object(piece)
     with pytest.raises(ValueError, match="Not able to equate"):
@@ -83,8 +86,9 @@ def test_bad_length():
         alpha.Split()(piece)
 
 
-def test_no_qutrits():
-    board = alpha.QuantumWorld()
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
+def test_no_qutrits(compile_to_qubits):
+    board = alpha.QuantumWorld(compile_to_qubits=compile_to_qubits)
     piece = alpha.QuantumObject("q0", 2)
     board.add_object(piece)
     with pytest.raises(ValueError, match="Cannot apply effect to qids"):

unitary/alpha/quantum_object_test.py

@@ -21,10 +21,13 @@
 from unitary.alpha.sparse_vector_simulator import SparseSimulator
 
 
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
 @pytest.mark.parametrize("simulator", [cirq.Simulator, SparseSimulator])
-def test_negation(simulator):
+def test_negation(simulator, compile_to_qubits):
     piece = alpha.QuantumObject("t", 0)
-    board = alpha.QuantumWorld(piece, sampler=simulator())
+    board = alpha.QuantumWorld(
+        piece, sampler=simulator(), compile_to_qubits=compile_to_qubits
+    )
     assert board.peek() == [[0]]
     -piece
     assert board.peek() == [[1]]
@@ -34,17 +37,21 @@ def test_negation(simulator):
     assert board.peek() == [[1]]
 
 
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
 @pytest.mark.parametrize("simulator", [cirq.Simulator, SparseSimulator])
-def test_add_world_after_state_change(simulator):
+def test_add_world_after_state_change(simulator, compile_to_qubits):
     piece = alpha.QuantumObject("t", 0)
     piece += 1
-    board = alpha.QuantumWorld(piece, sampler=simulator())
+    board = alpha.QuantumWorld(
+        piece, sampler=simulator(), compile_to_qubits=compile_to_qubits
+    )
     assert board.peek() == [[1]]
 
 
-def test_qutrit():
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
+def test_qutrit(compile_to_qubits):
     piece = alpha.QuantumObject("t", 2)
-    board = alpha.QuantumWorld(piece)
+    board = alpha.QuantumWorld(piece, compile_to_qubits=compile_to_qubits)
     assert board.peek() == [[2]]
     piece += 1
     assert board.peek() == [[0]]
@@ -58,14 +65,15 @@ def test_qutrit():
     assert board.peek() == [[2]]
 
 
-def test_enum():
+@pytest.mark.parametrize("compile_to_qubits", [False, True])
+def test_enum(compile_to_qubits):
     class Color(enum.Enum):
         RED = 0
         YELLOW = 1
         GREEN = 2
 
     piece = alpha.QuantumObject("t", Color.YELLOW)
-    board = alpha.QuantumWorld(piece)
+    board = alpha.QuantumWorld(piece, compile_to_qubits=compile_to_qubits)
     assert board.peek() == [[Color.YELLOW]]
     piece += Color.YELLOW
     assert board.peek() == [[Color.GREEN]]