Add check for hybrid Control/Matrix Gate classes + test

- Configured equivalence of gates from subclass to base class
- Renamed get_matrix to get_matrix_after_qubit_remapping and moved function to matrix_expander
- Added tests to check equivalence between MatrixGate and ControlGate objects

Author: juanboschero

.gitignore

@@ -153,6 +153,7 @@ dmypy.json
 cython_debug/
 
 # PyCharm
+.idea/
 #  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
 #  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear

opensquirrel/replacer.py

@@ -1,7 +1,6 @@
 from abc import ABC, abstractmethod
 from typing import Callable, List
 
-from opensquirrel.circuit_matrix_calculator import get_circuit_matrix
 from opensquirrel.common import are_matrices_equivalent_up_to_global_phase
 from opensquirrel.squirrel_ir import (
     BlochSphereRotation,
@@ -43,17 +42,6 @@ def visit_controlled_gate(self, controlled_gate: ControlledGate):
         return result
 
 
-def get_replacement_matrix(replacement: List[Gate], qubit_mappings):
-    replacement_ir = SquirrelIR(number_of_qubits=len(qubit_mappings), qubit_register_name="q_temp")
-    qubit_remapper = _QubitReIndexer(qubit_mappings)
-
-    for gate in replacement:
-        gate_with_remapped_qubits = gate.accept(qubit_remapper)
-        replacement_ir.add_gate(gate_with_remapped_qubits)
-
-    return get_circuit_matrix(replacement_ir)
-
-
 def check_valid_replacement(statement, replacement):
     expected_qubit_operands = statement.get_qubit_operands()
     replacement_qubit_operands = set()
@@ -62,8 +50,10 @@ def check_valid_replacement(statement, replacement):
     if set(expected_qubit_operands) != replacement_qubit_operands:
         raise Exception(f"Replacement for gate {statement.name} does not seem to operate on the right qubits")
 
-    replacement_matrix = get_replacement_matrix(replacement, expected_qubit_operands)
-    replaced_matrix = get_replacement_matrix([statement], expected_qubit_operands)
+    from opensquirrel.utils.matrix_expander import get_matrix_after_qubit_remapping
+
+    replacement_matrix = get_matrix_after_qubit_remapping(replacement, expected_qubit_operands)
+    replaced_matrix = get_matrix_after_qubit_remapping([statement], expected_qubit_operands)
 
     if not are_matrices_equivalent_up_to_global_phase(replacement_matrix, replaced_matrix):
         raise Exception(f"Replacement for gate {statement.name} does not preserve the quantum state")

opensquirrel/squirrel_ir.py

@@ -4,11 +4,19 @@
 from dataclasses import dataclass
 from functools import wraps
 from math import cos, sin
-from typing import Callable, List, Optional, Tuple
+from typing import Callable, List, Optional, Tuple, Union
 
 import numpy as np
 
-from opensquirrel.common import ATOL, X, Y, Z, normalize_angle, normalize_axis
+from opensquirrel.common import (
+    ATOL,
+    X,
+    Y,
+    Z,
+    are_matrices_equivalent_up_to_global_phase,
+    normalize_angle,
+    normalize_axis,
+)
 
 
 class SquirrelIRVisitor(ABC):
@@ -90,6 +98,11 @@ def __init__(self, generator, arguments):
         self.generator = generator
         self.arguments = arguments
 
+    def __eq__(self, other):
+        if not isinstance(other, Gate):
+            return False
+        return _compare_gate_classes(self, other)
+
     @property
     def name(self) -> Optional[str]:
         return self.generator.__name__ if self.generator else "<anonymous>"
@@ -171,12 +184,6 @@ def __init__(self, matrix: np.ndarray, operands: List[Qubit], generator=None, ar
         self.matrix = matrix
         self.operands = operands
 
-    def __eq__(self, other):
-        # TODO: Determine whether we shall allow for a global phase difference here.
-        if not isinstance(other, MatrixGate):
-            return False  # FIXME: a MatrixGate can hide a ControlledGate. https://github.com/QuTech-Delft/OpenSquirrel/issues/88
-        return np.allclose(self.matrix, other.matrix)
-
     def __repr__(self):
         return f"MatrixGate(qubits={self.operands}, matrix={self.matrix})"
 
@@ -199,14 +206,6 @@ def __init__(self, control_qubit: Qubit, target_gate: Gate, generator=None, argu
         self.control_qubit = control_qubit
         self.target_gate = target_gate
 
-    def __eq__(self, other):
-        if not isinstance(other, ControlledGate):
-            return False  # FIXME: a MatrixGate can hide a ControlledGate. https://github.com/QuTech-Delft/OpenSquirrel/issues/88
-        if self.control_qubit != other.control_qubit:
-            return False
-
-        return self.target_gate == other.target_gate
-
     def __repr__(self):
         return f"ControlledGate(control_qubit={self.control_qubit}, {self.target_gate})"
 
@@ -221,6 +220,18 @@ def is_identity(self) -> bool:
         return self.target_gate.is_identity()
 
 
+def _compare_gate_classes(g1: Gate, g2: Gate) -> bool:
+
+    union_mapping = list(set(g1.get_qubit_operands()) | set(g2.get_qubit_operands()))
+
+    from opensquirrel.utils.matrix_expander import get_matrix_after_qubit_remapping
+
+    matrix_g1 = get_matrix_after_qubit_remapping([g1], union_mapping)
+    matrix_g2 = get_matrix_after_qubit_remapping([g2], union_mapping)
+
+    return are_matrices_equivalent_up_to_global_phase(matrix_g1, matrix_g2)
+
+
 def named_gate(gate_generator: Callable[..., Gate]) -> Callable[..., Gate]:
     @wraps(gate_generator)
     def wrapper(*args, **kwargs):

opensquirrel/utils/__init__.py

@@ -0,0 +1,3 @@
+from opensquirrel.utils.matrix_expander import get_matrix, get_matrix_after_qubit_remapping
+
+__all__ = ["get_matrix", "get_matrix_after_qubit_remapping"]

opensquirrel/utils/matrix_expander.py

@@ -4,7 +4,8 @@
 import numpy as np
 
 from opensquirrel.common import can1
-from opensquirrel.squirrel_ir import BlochSphereRotation, ControlledGate, Gate, Qubit, SquirrelIRVisitor
+from opensquirrel.replacer import _QubitReIndexer
+from opensquirrel.squirrel_ir import BlochSphereRotation, ControlledGate, Gate, Qubit, SquirrelIR, SquirrelIRVisitor
 
 
 def get_reduced_ket(ket: int, qubits: List[Qubit]) -> int:
@@ -183,3 +184,15 @@ def get_matrix(gate: Gate, number_of_qubits: int) -> np.ndarray:
 
     expander = MatrixExpander(number_of_qubits)
     return gate.accept(expander)
+
+
+def get_matrix_after_qubit_remapping(replacement: List[Gate], qubit_mappings: List[Qubit]):
+    from opensquirrel.circuit_matrix_calculator import get_circuit_matrix
+
+    replacement_ir = SquirrelIR(number_of_qubits=len(qubit_mappings), qubit_register_name="q_temp")
+    qubit_remapper = _QubitReIndexer(qubit_mappings)
+    for gate in replacement:
+        gate_with_remapped_qubits = gate.accept(qubit_remapper)
+        replacement_ir.add_gate(gate_with_remapped_qubits)
+
+    return get_circuit_matrix(replacement_ir)

test/test_squirrel_ir.py

@@ -0,0 +1,101 @@
+import unittest
+
+import numpy as np
+
+from opensquirrel.default_gates import *
+
+
+class SquirrelIRTest(unittest.TestCase):
+    def test_cnot_equality(self):
+        cnot_matrix_gate = MatrixGate(
+            np.array(
+                [
+                    [1, 0, 0, 0],
+                    [0, 1, 0, 0],
+                    [0, 0, 0, 1],
+                    [0, 0, 1, 0],
+                ]
+            ),
+            operands=[Qubit(4), Qubit(100)],
+        )
+
+        cnot_controlled_gate = ControlledGate(
+            Qubit(4), BlochSphereRotation(qubit=Qubit(100), axis=(1, 0, 0), angle=math.pi, phase=math.pi / 2)
+        )
+
+        self.assertTrue(cnot_controlled_gate == cnot_matrix_gate)
+
+    def test_cnot_inequality(self):
+        swap_matrix_gate = MatrixGate(
+            np.array(
+                [
+                    [1, 0, 0, 0],
+                    [0, 0, 1, 0],
+                    [0, 1, 0, 0],
+                    [0, 0, 0, 1],
+                ]
+            ),
+            operands=[Qubit(4), Qubit(100)],
+        )
+
+        cnot_controlled_gate = ControlledGate(
+            Qubit(4), BlochSphereRotation(qubit=Qubit(100), axis=(1, 0, 0), angle=math.pi, phase=math.pi / 2)
+        )
+
+        self.assertFalse(cnot_controlled_gate == swap_matrix_gate)
+
+    def test_different_qubits_gate(self):
+        large_identity_matrix_gate = MatrixGate(
+            np.array(
+                [
+                    [1, 0, 0, 0],
+                    [0, 1, 0, 0],
+                    [0, 0, 1, 0],
+                    [0, 0, 0, 1],
+                ]
+            ),
+            operands=[Qubit(0), Qubit(2)],
+        )
+        small_identity_control_gate = ControlledGate(
+            Qubit(4), BlochSphereRotation(qubit=Qubit(2), axis=(1, 0, 0), angle=0, phase=0)
+        )
+
+        self.assertTrue(large_identity_matrix_gate == small_identity_control_gate)
+
+    def test_inverse_gate(self):
+        inverted_matrix_gate = MatrixGate(
+            np.array(
+                [
+                    [1, 0, 0, 0],
+                    [0, 0, 0, 1],
+                    [0, 0, 1, 0],
+                    [0, 1, 0, 0],
+                ]
+            ),
+            operands=[Qubit(0), Qubit(1)],
+        )
+
+        inverted_cnot_gate = ControlledGate(
+            Qubit(1), BlochSphereRotation(qubit=Qubit(0), axis=(1, 0, 0), angle=math.pi, phase=math.pi / 2)
+        )
+
+        self.assertTrue(inverted_matrix_gate == inverted_cnot_gate)
+
+    def test_global_phase(self):
+        inverted_matrix_with_phase = MatrixGate(
+            np.array(
+                [
+                    [1j, 0, 0, 0],
+                    [0, 0, 0, 1j],
+                    [0, 0, 1j, 0],
+                    [0, 1j, 0, 0],
+                ]
+            ),
+            operands=[Qubit(0), Qubit(1)],
+        )
+
+        inverted_cnot_gate = ControlledGate(
+            Qubit(1), BlochSphereRotation(qubit=Qubit(0), axis=(1, 0, 0), angle=math.pi, phase=math.pi / 2)
+        )
+
+        self.assertTrue(inverted_matrix_with_phase == inverted_cnot_gate)