diff --git a/docs/changelog.rst b/docs/changelog.rst
index b766bec..203daa2 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -5,6 +5,9 @@ Changelog
 ------------
 
 * Add simple automatic placement and routing for multi-zone architectures
+* Don't include ``SimplifyInitial`` in default passes; instead make it an option
+  to ``process_circuits()``.
+
 
 0.29.0rc0 (July 2023)
 ---------------------
diff --git a/pytket/extensions/aqt/backends/aqt.py b/pytket/extensions/aqt/backends/aqt.py
index 629530f..c1761fe 100644
--- a/pytket/extensions/aqt/backends/aqt.py
+++ b/pytket/extensions/aqt/backends/aqt.py
@@ -216,9 +216,6 @@ def default_compilation_pass(self, optimisation_level: int = 2) -> BasePass:
                     FlattenRegisters(),
                     RenameQubitsPass(self._qm),
                     self.rebase_pass(),
-                    SimplifyInitial(
-                        allow_classical=False, create_all_qubits=True, xcirc=_xcirc
-                    ),
                     EulerAngleReduction(OpType.Ry, OpType.Rx),
                 ]
             )
@@ -230,9 +227,6 @@ def default_compilation_pass(self, optimisation_level: int = 2) -> BasePass:
                     FlattenRegisters(),
                     RenameQubitsPass(self._qm),
                     self.rebase_pass(),
-                    SimplifyInitial(
-                        allow_classical=False, create_all_qubits=True, xcirc=_xcirc
-                    ),
                     EulerAngleReduction(OpType.Ry, OpType.Rx),
                 ]
             )
@@ -250,7 +244,13 @@ def process_circuits(
     ) -> List[ResultHandle]:
         """
         See :py:meth:`pytket.backends.Backend.process_circuits`.
-        Supported kwargs: none.
+
+        Supported kwargs:
+        - `postprocess`: apply end-of-circuit simplifications and classical
+          postprocessing to improve fidelity of results (bool, default False)
+        - `simplify_initial`: apply the pytket ``SimplifyInitial`` pass to improve
+          fidelity of results assuming all qubits initialized to zero (bool, default
+          False)
         """
         circuits = list(circuits)
         n_shots_list = Backend._get_n_shots_as_list(
@@ -263,6 +263,7 @@ def process_circuits(
             self._check_all_circuits(circuits)
 
         postprocess = kwargs.get("postprocess", False)
+        simplify_initial = kwargs.get("postprocess", False)
 
         handles = []
         for i, (c, n_shots) in enumerate(zip(circuits, n_shots_list)):
@@ -271,6 +272,10 @@ def process_circuits(
                 ppcirc_rep = ppcirc.to_dict()
             else:
                 c0, ppcirc_rep = c, None
+            if simplify_initial:
+                SimplifyInitial(
+                    allow_classical=False, create_all_qubits=True, xcirc=_xcirc
+                ).apply(c0)
             (aqt_circ, measures) = _translate_aqt(c0)
             if self._MACHINE_DEBUG:
                 handles.append(
diff --git a/pytket/extensions/aqt/backends/aqt_multi_zone.py b/pytket/extensions/aqt/backends/aqt_multi_zone.py
index f37cd0a..cd75e53 100644
--- a/pytket/extensions/aqt/backends/aqt_multi_zone.py
+++ b/pytket/extensions/aqt/backends/aqt_multi_zone.py
@@ -42,7 +42,6 @@
 from pytket.passes import FullPeepholeOptimise
 from pytket.passes import RenameQubitsPass
 from pytket.passes import SequencePass
-from pytket.passes import SimplifyInitial
 from pytket.passes import SynthesiseTket
 from pytket.predicates import GateSetPredicate
 from pytket.predicates import MaxNQubitsPredicate
@@ -200,9 +199,6 @@ def default_compilation_pass(self, optimisation_level: int = 2) -> SequencePass:
                     FlattenRegisters(),
                     RenameQubitsPass(self._qm),
                     self.rebase_pass(),
-                    SimplifyInitial(
-                        allow_classical=False, create_all_qubits=True, xcirc=_xcirc
-                    ),
                     EulerAngleReduction(OpType.Ry, OpType.Rx),
                 ]
             )
@@ -214,9 +210,6 @@ def default_compilation_pass(self, optimisation_level: int = 2) -> SequencePass:
                     FlattenRegisters(),
                     RenameQubitsPass(self._qm),
                     self.rebase_pass(),
-                    SimplifyInitial(
-                        allow_classical=False, create_all_qubits=True, xcirc=_xcirc
-                    ),
                     EulerAngleReduction(OpType.Ry, OpType.Rx),
                 ]
             )
@@ -495,7 +488,3 @@ def swap_position(qubit_1_: int, qubit_2_: int) -> None:
 
 def _aqt_rebase() -> BasePass:
     return auto_rebase_pass({OpType.XXPhase, OpType.Rx, OpType.Ry})
-
-
-_xcirc = Circuit(1).Rx(1, 0)
-_xcirc.add_phase(0.5)