New atomic_evolution signature in ProductFormula subclasses (Qiskit#13918)

* new atomic_evolution signature in ProductFormula subclasses

* Add LieTrotter to reno

---------

Co-authored-by: Julien Gacon <[email protected]>

Author: 1ucian0

qiskit/synthesis/evolution/lie_trotter.py

@@ -55,9 +55,7 @@ def __init__(
         insert_barriers: bool = False,
         cx_structure: str = "chain",
         atomic_evolution: (
-            Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]
-            | Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]
-            | None
+            Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None] | None
         ) = None,
         wrap: bool = False,
         preserve_order: bool = True,
@@ -75,9 +73,6 @@ def __init__(
                 three arguments: the circuit to append the evolution to, the Pauli operator to
                 evolve, and the evolution time. By default, a single Pauli evolution is decomposed
                 into a chain of ``CX`` gates and a single ``RZ`` gate.
-                Alternatively, the function can also take Pauli operator and evolution time as
-                inputs and returns the circuit that will be appended to the overall circuit being
-                built.
             wrap: Whether to wrap the atomic evolutions into custom gate objects. This only takes
                 effect when ``atomic_evolution is None``.
             preserve_order: If ``False``, allows reordering the terms of the operator to

qiskit/synthesis/evolution/product_formula.py

@@ -25,7 +25,6 @@
 from qiskit.circuit.parameterexpression import ParameterExpression
 from qiskit.circuit.quantumcircuit import QuantumCircuit, ParameterValueType
 from qiskit.quantum_info import SparsePauliOp, Pauli
-from qiskit.utils.deprecation import deprecate_arg
 from qiskit._accelerate.circuit_library import pauli_evolution
 
 from .evolution_synthesis import EvolutionSynthesis
@@ -42,31 +41,14 @@ class ProductFormula(EvolutionSynthesis):
     :obj:`.LieTrotter` and :obj:`.SuzukiTrotter` inherit from this class.
     """
 
-    @deprecate_arg(
-        name="atomic_evolution",
-        since="1.2",
-        predicate=lambda callable: callable is not None
-        and len(inspect.signature(callable).parameters) == 2,
-        deprecation_description=(
-            "The 'Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]' signature of the "
-            "'atomic_evolution' argument"
-        ),
-        additional_msg=(
-            "Instead you should update your 'atomic_evolution' function to be of the following "
-            "type: 'Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]'."
-        ),
-        pending=True,
-    )
     def __init__(
         self,
         order: int,
         reps: int = 1,
         insert_barriers: bool = False,
         cx_structure: str = "chain",
         atomic_evolution: (
-            Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]
-            | Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]
-            | None
+            Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None] | None
         ) = None,
         wrap: bool = False,
         preserve_order: bool = True,
@@ -85,9 +67,6 @@ def __init__(
                 three arguments: the circuit to append the evolution to, the Pauli operator to
                 evolve, and the evolution time. By default, a single Pauli evolution is decomposed
                 into a chain of ``CX`` gates and a single ``RZ`` gate.
-                Alternatively, the function can also take Pauli operator and evolution time as
-                inputs and returns the circuit that will be appended to the overall circuit being
-                built.
             wrap: Whether to wrap the atomic evolutions into custom gate objects. Note that setting
                 this to ``True`` is slower than ``False``. This only takes effect when
                 ``atomic_evolution is None``.

qiskit/synthesis/evolution/qdrift.py

@@ -14,15 +14,13 @@
 
 from __future__ import annotations
 
-import inspect
 import math
 import typing
 from itertools import chain
 from collections.abc import Callable
 import numpy as np
 from qiskit.circuit.quantumcircuit import QuantumCircuit
 from qiskit.quantum_info.operators import SparsePauliOp, Pauli
-from qiskit.utils.deprecation import deprecate_arg
 from qiskit.exceptions import QiskitError
 
 from .product_formula import ProductFormula, reorder_paulis
@@ -41,30 +39,13 @@ class QDrift(ProductFormula):
         `arXiv:quant-ph/1811.08017 <https://arxiv.org/abs/1811.08017>`_
     """
 
-    @deprecate_arg(
-        name="atomic_evolution",
-        since="1.2",
-        predicate=lambda callable: callable is not None
-        and len(inspect.signature(callable).parameters) == 2,
-        deprecation_description=(
-            "The 'Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]' signature of the "
-            "'atomic_evolution' argument"
-        ),
-        additional_msg=(
-            "Instead you should update your 'atomic_evolution' function to be of the following "
-            "type: 'Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]'."
-        ),
-        pending=True,
-    )
     def __init__(
         self,
         reps: int = 1,
         insert_barriers: bool = False,
         cx_structure: str = "chain",
         atomic_evolution: (
-            Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]
-            | Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]
-            | None
+            Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None] | None
         ) = None,
         seed: int | None = None,
         wrap: bool = False,
@@ -83,9 +64,6 @@ def __init__(
                 three arguments: the circuit to append the evolution to, the Pauli operator to
                 evolve, and the evolution time. By default, a single Pauli evolution is decomposed
                 into a chain of ``CX`` gates and a single ``RZ`` gate.
-                Alternatively, the function can also take Pauli operator and evolution time as
-                inputs and returns the circuit that will be appended to the overall circuit being
-                built.
             seed: An optional seed for reproducibility of the random sampling process.
             wrap: Whether to wrap the atomic evolutions into custom gate objects. This only takes
                 effect when ``atomic_evolution is None``.

qiskit/synthesis/evolution/suzuki_trotter.py

@@ -14,7 +14,6 @@
 
 from __future__ import annotations
 
-import inspect
 import typing
 from collections.abc import Callable
 from itertools import chain
@@ -23,7 +22,6 @@
 from qiskit.circuit.parameterexpression import ParameterExpression
 from qiskit.circuit.quantumcircuit import QuantumCircuit
 from qiskit.quantum_info.operators import SparsePauliOp, Pauli
-from qiskit.utils.deprecation import deprecate_arg
 
 from .product_formula import ProductFormula, reorder_paulis
 
@@ -60,31 +58,14 @@ class SuzukiTrotter(ProductFormula):
         `arXiv:math-ph/0506007 <https://arxiv.org/pdf/math-ph/0506007.pdf>`_
     """
 
-    @deprecate_arg(
-        name="atomic_evolution",
-        since="1.2",
-        predicate=lambda callable: callable is not None
-        and len(inspect.signature(callable).parameters) == 2,
-        deprecation_description=(
-            "The 'Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]' signature of the "
-            "'atomic_evolution' argument"
-        ),
-        additional_msg=(
-            "Instead you should update your 'atomic_evolution' function to be of the following "
-            "type: 'Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]'."
-        ),
-        pending=True,
-    )
     def __init__(
         self,
         order: int = 2,
         reps: int = 1,
         insert_barriers: bool = False,
         cx_structure: str = "chain",
         atomic_evolution: (
-            Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]
-            | Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]
-            | None
+            Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None] | None
         ) = None,
         wrap: bool = False,
         preserve_order: bool = True,
@@ -102,9 +83,6 @@ def __init__(
                 three arguments: the circuit to append the evolution to, the Pauli operator to
                 evolve, and the evolution time. By default, a single Pauli evolution is decomposed
                 into a chain of ``CX`` gates and a single ``RZ`` gate.
-                Alternatively, the function can also take Pauli operator and evolution time as
-                inputs and returns the circuit that will be appended to the overall circuit being
-                built.
             wrap: Whether to wrap the atomic evolutions into custom gate objects. This only takes
                 effect when ``atomic_evolution is None``.
             preserve_order: If ``False``, allows reordering the terms of the operator to

releasenotes/notes/fixes_13858-2dacfc0431c1a6ea.yaml

@@ -0,0 +1,10 @@
+---
+upgrade_synthesis:
+  - |
+    The ``atomic_evolution`` argument to :class:`.ProductFormula` (and its
+    subclasses :class:`.QDrift`, :class:`.LieTrotter` and :class:`SuzukiTrotter` ) 
+    has a new function signature. Rather than taking some Pauli
+    operator and time coefficient and returning the evolution circuit, the new
+    function takes in an existing circuit and should append the evolution of the
+    provided Pauli and given time to this circuit. This new implementation
+    benefits from significantly better performance.

test/python/circuit/library/test_evolution_gate.py

@@ -442,7 +442,7 @@ def test_labels_and_name(self):
     def test_atomic_evolution(self):
         """Test a custom atomic_evolution."""
 
-        def atomic_evolution(pauli, time):
+        def atomic_evolution(circuit, pauli, time):
             if isinstance(pauli, SparsePauliOp):
                 if len(pauli.paulis) != 1:
                     raise ValueError("Unsupported input.")
@@ -458,24 +458,20 @@ def atomic_evolution(pauli, time):
                     target = i
                     break
 
-            definition = QuantumCircuit(pauli.num_qubits)
-            definition.compose(cliff, inplace=True)
-            definition.compose(chain, inplace=True)
-            definition.rz(2 * time, target)
-            definition.compose(chain.inverse(), inplace=True)
-            definition.compose(cliff.inverse(), inplace=True)
-
-            return definition
+            circuit.compose(cliff, inplace=True)
+            circuit.compose(chain, inplace=True)
+            circuit.rz(2 * time, target)
+            circuit.compose(chain.inverse(), inplace=True)
+            circuit.compose(cliff.inverse(), inplace=True)
 
         op = (X ^ X ^ X) + (Y ^ Y ^ Y) + (Z ^ Z ^ Z)
         time = 0.123
         reps = 4
-        with self.assertWarns(PendingDeprecationWarning):
-            evo_gate = PauliEvolutionGate(
-                op,
-                time,
-                synthesis=LieTrotter(reps=reps, atomic_evolution=atomic_evolution),
-            )
+        evo_gate = PauliEvolutionGate(
+            op,
+            time,
+            synthesis=LieTrotter(reps=reps, atomic_evolution=atomic_evolution),
+        )
         decomposed = evo_gate.definition.decompose()
         self.assertEqual(decomposed.count_ops()["cx"], reps * 3 * 4)