Deprecates StochasticSwap and suggests the use of SabreSwap

qiskit/transpiler/passes/routing/stochastic_swap.py

@@ -38,6 +38,7 @@
 from qiskit._accelerate import stochastic_swap as stochastic_swap_rs
 from qiskit._accelerate import nlayout
 from qiskit.transpiler.passes.layout import disjoint_utils
+from qiskit.utils import deprecate_func
 
 from .utils import get_swap_map_dag
 
@@ -59,6 +60,12 @@ class StochasticSwap(TransformationPass):
            the circuit.
     """
 
+    @deprecate_func(
+        since="1.3",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The `StochasticSwap` tranpilation pass is a suboptimal "
+        "routing algorithm and will has been superseded by :class:`.SabreSwap` pass.",
+    )
     def __init__(self, coupling_map, trials=20, seed=None, fake_run=False, initial_layout=None):
         """StochasticSwap initializer.
 
@@ -76,6 +83,7 @@ def __init__(self, coupling_map, trials=20, seed=None, fake_run=False, initial_l
             initial_layout (Layout): starting layout at beginning of pass.
         """
         super().__init__()
+
         if isinstance(coupling_map, Target):
             self.target = coupling_map
             self.coupling_map = self.target.build_coupling_map()

releasenotes/notes/deprecate-StochasticSwap-451f46b273602b7b.yaml

@@ -0,0 +1,46 @@
+---
+deprecations_transpiler:
+  - |
+    Deprecated ``StochasticSwap`` which has been superseded by :class:`.SabreSwap`. 
+    If the class is called from the transpile method, the change would be, for example:: 
+
+      tqc = transpile(
+        circuit,
+        routing_method="stochastic",
+        layout_method="dense",
+        seed_transpiler=12342,
+        target=GenericBackendV2(
+            num_qubits=27,
+            coupling_map=MUMBAI_CMAP,
+        ).target,
+        ) 
+
+    to::
+
+      tqc = transpile(
+        circuit,
+        routing_method="sabre",
+        layout_method="sabre",
+        seed_transpiler=12342,
+        target=GenericBackendV2(
+            num_qubits=27,
+            coupling_map=MUMBAI_CMAP,
+        ).target,
+        )   
+
+    While for a pass mananager change::
+
+      qr = QuantumRegister(4, "q")
+      qc = QuantumCircuit(qr)
+      passmanager = StochasticSwap(coupling, 20, 13)
+      new_qc = passmanager.run(qc)
+
+    to::
+
+      qr = QuantumRegister(5, "q")
+      qc = QuantumCircuit(qr) 
+      passmanager = PassManager(SabreSwap(target, "basic"))
+      new_qc = passmanager.run(qc)
+
+
+