Merge pull request #160 from QuTech-Delft/152-basic-implementation-ma…

…pper

152 basic implementation mapper

opensquirrel/circuit.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from typing import Callable, Dict
 
 import numpy as np
@@ -9,6 +11,7 @@
 from opensquirrel.default_measurements import default_measurement_set
 from opensquirrel.exporter import quantify_scheduler_exporter, writer
 from opensquirrel.exporter.export_format import ExportFormat
+from opensquirrel.mapper import IdentityMapper, Mapper, map_qubits
 from opensquirrel.merger import general_merger
 from opensquirrel.parser.libqasm.libqasm_ir_creator import LibqasmIRCreator
 from opensquirrel.squirrel_ir import Gate, Measure, SquirrelIR
@@ -95,6 +98,17 @@ def decompose(self, decomposer: Decomposer):
         """Generic decomposition pass. It applies the given decomposer function to every gate in the circuit."""
         general_decomposer.decompose(self.squirrel_ir, decomposer)
 
+    def map_qubits(self, mapper: Mapper | None = None) -> None:
+        """Generic qubit mapper pass.
+
+        Maps the virtual qubits of the circuit to physical qubits of the target hardware.
+
+        Args:
+            mapper: Mapper pass to use. If ``None`` (default) is provided, use the ``IdentityMapper``.
+        """
+        mapper = IdentityMapper() if mapper is None else mapper
+        map_qubits(self.squirrel_ir, mapper)
+
     def replace(self, gate_generator: Callable[..., Gate], f):
         """Manually replace occurrences of a given gate with a list of gates.
         `f` is a callable that takes the arguments of the gate that is to be replaced

opensquirrel/mapper/__init__.py

@@ -0,0 +1,4 @@
+from opensquirrel.mapper.general_mapper import Mapper, map_qubits
+from opensquirrel.mapper.simple_mappers import HardcodedMapper, IdentityMapper
+
+__all__ = ["map_qubits", "Mapper", "IdentityMapper", "HardcodedMapper"]

opensquirrel/mapper/general_mapper.py

@@ -0,0 +1,37 @@
+"""This module contains generic mapping components."""
+
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+
+from opensquirrel.squirrel_ir import Gate, Measure, SquirrelIR
+
+
+def map_qubits(squirrel_ir: SquirrelIR, mapper: Mapper) -> None:
+    """Map the virtual qubits in the `squirrel_ir` to physical qubits using `mapper`.
+
+    Args:
+        squirrel_ir: IR to apply mapping to.
+        mapper: Mapping pass to use.
+    """
+
+    mapping = mapper.map(squirrel_ir)
+
+    for statement in squirrel_ir.statements:
+        if isinstance(statement, (Gate, Measure)):
+            statement.relabel(mapping)
+
+
+class Mapper(ABC):
+    """Base class for the Mapper pass."""
+
+    @abstractmethod
+    def map(self, squirrel_ir: SquirrelIR) -> dict[int, int]:
+        """Produce a mapping from the virtual qubits in the `squirrel_ir` to the physical qubits.
+
+        Args:
+            squirrel_ir: IR to apply mapping to.
+
+        Returns:
+            Mapping from virtual qubits to physical qubits.
+        """

opensquirrel/mapper/simple_mappers.py

@@ -0,0 +1,59 @@
+"""This module contains the following simple mappers:
+
+* IdentityMapper
+* HardcodedMapper
+"""
+
+from __future__ import annotations
+
+from collections.abc import Mapping
+from typing import SupportsInt
+
+from opensquirrel.mapper.general_mapper import Mapper
+from opensquirrel.squirrel_ir import SquirrelIR
+
+
+class IdentityMapper(Mapper):
+
+    def map(self, squirrel_ir: SquirrelIR) -> dict[int, int]:
+        """Produce an IdentityMapping.
+
+        Args:
+            squirrel_ir: IR to map.
+
+        Returns:
+            Mapping from virtual qubits to physical qubits. Each virtual qubit is mapped to the physical qubit with
+            the same index.
+        """
+        return {i: i for i in range(squirrel_ir.number_of_qubits)}
+
+
+class HardcodedMapper(Mapper):
+
+    def __init__(self, mapping: Mapping[SupportsInt, SupportsInt]) -> None:
+        """Init of the ``HardcodedMapper``.
+
+        Args:
+            mapping: Mapping with as keys the virtual qubits and as values the physical qubits.
+
+        Raises:
+            ValueError: If `mapping` is not a valid mapping.
+        """
+        # Check if the provided mapping is valid
+        self.mapping = {int(virtual_qubit): int(physical_qubit) for virtual_qubit, physical_qubit in mapping.items()}
+        if set(self.mapping.keys()) != set(self.mapping.values()):
+            raise ValueError("The set of physical qubits is not equal to the set of virtual qubits.")
+
+    def map(self, squirrel_ir: SquirrelIR) -> dict[int, int]:
+        """Retrieve the hardcoded mapping.
+
+        Args:
+            squirrel_ir: IR to apply mapping to.
+
+        Returns:
+            Mapping from virtual qubits to physical qubits.
+        """
+        if set(range(squirrel_ir.number_of_qubits)) != set(self.mapping.keys()):
+            raise ValueError("Virtual qubits are not labeled correctly.")
+
+        return self.mapping

opensquirrel/mapper/utils.py

@@ -0,0 +1,22 @@
+import networkx as nx
+
+from opensquirrel.squirrel_ir import Gate, SquirrelIR
+
+
+def make_interaction_graph(squirrel_ir: SquirrelIR) -> nx.Graph:
+
+    interaction_graph = nx.Graph()
+    gates = (statement for statement in squirrel_ir.statements if isinstance(statement, Gate))
+
+    for gate in gates:
+        target_qubits = gate.get_qubit_operands()
+        if len(target_qubits) == 1:
+            continue
+        if len(target_qubits) > 2:
+            raise ValueError(
+                f"The gate {gate} acts on more than 2 qubits. The gate must be decomposed before an interaction graph "
+                "can be made."
+            )
+        interaction_graph.add_edge(*target_qubits)
+
+    return interaction_graph

opensquirrel/squirrel_ir.py

@@ -1,5 +1,8 @@
+from __future__ import annotations
+
 import inspect
 from abc import ABC, abstractmethod
+from collections.abc import Mapping
 from dataclasses import dataclass
 from functools import wraps
 from typing import Callable, List, Optional, Tuple
@@ -108,14 +111,22 @@ def name(self) -> Optional[str]:
     def __eq__(self, other):
         if not isinstance(other, Measure):
             return False
-        return self.qubit == other.qubit and self.axis == other.axis
+        return self.qubit == other.qubit and np.allclose(self.axis, other.axis, atol=ATOL)
 
     def accept(self, visitor: SquirrelIRVisitor):
         visitor.visit_measure(self)
 
     def get_qubit_operands(self) -> List[Qubit]:
         return [self.qubit]
 
+    def relabel(self, mapping: Mapping[int, int]) -> None:
+        """Relabel the qubits using the given mapping.
+
+        Args:
+            mapping: Mapping from the indices of the original qubits to the indices of the qubits after replacement.
+        """
+        self.qubit = Qubit(mapping[self.qubit.index])
+
 
 class Gate(Statement, ABC):
     # Note: two gates are considered equal even when their generators/arguments are different.
@@ -141,11 +152,28 @@ def is_anonymous(self) -> bool:
 
     @abstractmethod
     def get_qubit_operands(self) -> List[Qubit]:
-        raise NotImplementedError
+        """Get the qubit operands of the Gate.
+
+        Returns:
+            List of qubits on which the Gate operates.
+        """
 
     @abstractmethod
     def is_identity(self) -> bool:
-        raise NotImplementedError
+        """Check wether the Gate is an identity Gate.
+
+        Returns:
+            Boolean value stating wether the Gate is an identity Gate.
+        """
+
+    @abstractmethod
+    def relabel(self, mapping: Mapping[int, int]) -> None:
+        """Relabel the qubits using the given mapping.
+
+        Args:
+            mapping: Mapping from the indices of the original qubits to the indices of the qubits
+            after replacement.
+        """
 
 
 class BlochSphereRotation(Gate):
@@ -200,6 +228,15 @@ def is_identity(self) -> bool:
         # Angle and phase are already normalized.
         return abs(self.angle) < ATOL and abs(self.phase) < ATOL
 
+    def relabel(self, mapping: Mapping[int, int]) -> None:
+        """Relabel the qubits using the given mapping.
+
+        Args:
+            mapping: Mapping from the indices of the original qubits to the indices of the qubits
+            after replacement.
+        """
+        self.qubit = Qubit(mapping[self.qubit.index])
+
 
 class MatrixGate(Gate):
     generator: Optional[Callable[..., "MatrixGate"]] = None
@@ -225,6 +262,15 @@ def get_qubit_operands(self) -> List[Qubit]:
     def is_identity(self) -> bool:
         return np.allclose(self.matrix, np.eye(2 ** len(self.operands)))
 
+    def relabel(self, mapping: Mapping[int, int]) -> None:
+        """Relabel the qubits using the given mapping.
+
+        Args:
+            mapping: Mapping from the indices of the original qubits to the indices of the qubits
+            after replacement.
+        """
+        self.operands = [Qubit(mapping[qubit.index]) for qubit in self.operands]
+
 
 class ControlledGate(Gate):
     generator: Optional[Callable[..., "ControlledGate"]] = None
@@ -247,6 +293,16 @@ def get_qubit_operands(self) -> List[Qubit]:
     def is_identity(self) -> bool:
         return self.target_gate.is_identity()
 
+    def relabel(self, mapping: Mapping[int, int]) -> None:
+        """Relabel the qubits using the given mapping.
+
+        Args:
+            mapping: Mapping from the indices of the original qubits to the indices of the qubits
+            after replacement.
+        """
+        self.control_qubit = Qubit(mapping[self.control_qubit.index])
+        self.target_gate.relabel(mapping)
+
 
 def _compare_gate_classes(g1: Gate, g2: Gate) -> bool:
     union_mapping = list(set(g1.get_qubit_operands()) | set(g2.get_qubit_operands()))

opensquirrel/utils/check_passes/__init__.py

@@ -0,0 +1,5 @@
+"""Ths subpackage contains compatibility checks for the different compilation passes."""
+
+from opensquirrel.utils.check_passes.check_mapper import check_mapper
+
+__all__ = ["check_mapper"]

opensquirrel/utils/check_passes/check_mapper.py

@@ -0,0 +1,61 @@
+"""This module contains checks for the ``Mapper`` pass."""
+
+from __future__ import annotations
+
+from copy import deepcopy
+
+from opensquirrel.mapper.general_mapper import Mapper
+from opensquirrel.squirrel_ir import BlochSphereRotation, Comment, ControlledGate, Measure, Qubit, SquirrelIR
+
+
+def check_mapper(mapper: Mapper) -> None:
+    """Check if the `mapper` complies with the OpenSquirrel requirements.
+
+    If an implementation of ``Mapper`` passes these checks it should be compatible with the ``Circuit.map_qubits``
+    method.
+
+    Args:
+        mapper: Mapper to check.
+    """
+
+    assert isinstance(mapper, Mapper)
+
+    squirrel_ir = SquirrelIR(number_of_qubits=10)
+    _check_scenario(squirrel_ir, mapper)
+
+    squirrel_ir = SquirrelIR(number_of_qubits=10)
+    squirrel_ir.add_comment(Comment("comment"))
+    squirrel_ir.add_gate(BlochSphereRotation(Qubit(42), (1, 0, 0), 1, 2))
+    squirrel_ir.add_gate(ControlledGate(Qubit(42), BlochSphereRotation.identity(Qubit(100))))
+    squirrel_ir.add_measurement(Measure(Qubit(42), (0, 0, 1)))
+    _check_scenario(squirrel_ir, mapper)
+
+
+def _check_scenario(squirrel_ir: SquirrelIR, mapper: Mapper) -> None:
+    """Check if the given scenario can be mapped.
+
+    Args:
+        squirrel_ir: SquirrelIR containing the scenario to check against.
+        mapping: Mapping to check.
+    """
+    squirrel_ir_copy = deepcopy(squirrel_ir)
+    mapping = mapper.map(squirrel_ir)
+
+    assert squirrel_ir == squirrel_ir_copy, "A Mapper pass should not change the SquirrelIR."
+    _check_mapping_format(mapping, squirrel_ir.number_of_qubits)
+
+
+def _check_mapping_format(mapping: dict[int, int], number_of_qubits: int) -> None:
+    """Check if the mapping has the expected format.
+
+    Args:
+        mapping: Mapping to check.
+        n_qubits: Number of qubits in the circuit.
+    """
+    assert isinstance(
+        mapping, dict
+    ), f"Output mapping should be an instance of <class 'dict'>, but was of type {type(mapping)}"
+    assert set(mapping.keys()) == set(
+        mapping.values()
+    ), "The set of virtual qubits is not equal to the set of phyical qubits."
+    assert set(range(number_of_qubits)) == set(mapping.keys()), "Virtual qubits are not labeled correctly."

pyproject.toml

@@ -36,6 +36,7 @@ numpy = [
     { version = "^1.26", python = "^3.9" },
 ]
 libqasm = "0.6.5"
+networkx = "^3.0.0"
 
 [tool.poetry.group.dev.dependencies]
 black = ">=23.11,<25.0"