We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Add insert_barrier argument to UnitaryOverlap
### What should we add?

This argument would insert a barrier between the two unitaries. This is useful if you want to prevent circuit optimization between the two parts.

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `qiskit/circuit/library/overlap.py`
Content:
```
1 # This code is part of Qiskit.
2 #
3 # (C) Copyright IBM 2023.
4 #
5 # This code is licensed under the Apache License, Version 2.0. You may
6 # obtain a copy of this license in the LICENSE.txt file in the root directory
7 # of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
8 #
9 # Any modifications or derivative works of this code must retain this
10 # copyright notice, and modified files need to carry a notice indicating
11 # that they have been altered from the originals.
12 
13 """Unitary overlap circuit."""
14 
15 from qiskit.circuit import QuantumCircuit, Gate
16 from qiskit.circuit.parametervector import ParameterVector
17 from qiskit.circuit.exceptions import CircuitError
18 from qiskit.circuit import Barrier
19 
20 
21 class UnitaryOverlap(QuantumCircuit):
22     r"""Circuit that returns the overlap between two unitaries :math:`U_2^{\dag} U_1`.
23 
24     The input quantum circuits must represent unitary operations, since they must be invertible.
25     If the inputs will have parameters, they are replaced by :class:`.ParameterVector`\s with
26     names `"p1"` (for circuit ``unitary1``) and `"p2"` (for circuit ``unitary_2``) in the output
27     circuit.
28 
29     This circuit is usually employed in computing the fidelity:
30 
31     .. math::
32 
33         \left|\langle 0| U_2^{\dag} U_1|0\rangle\right|^{2}
34 
35     by computing the probability of being in the all-zeros bit-string, or equivalently,
36     the expectation value of projector :math:`|0\rangle\langle 0|`.
37 
38     Example::
39 
40         import numpy as np
41         from qiskit.circuit.library import EfficientSU2, UnitaryOverlap
42         from qiskit.primitives import Sampler
43 
44         # get two circuit to prepare states of which we comput the overlap
45         circuit = EfficientSU2(2, reps=1)
46         unitary1 = circuit.assign_parameters(np.random.random(circuit.num_parameters))
47         unitary2 = circuit.assign_parameters(np.random.random(circuit.num_parameters))
48 
49         # create the overlap circuit
50         overlap = UnitaryOverap(unitary1, unitary2)
51 
52         # sample from the overlap
53         sampler = Sampler(options={"shots": 100})
54         result = sampler.run(overlap).result()
55 
56         # the fidelity is the probability to measure 0
57         fidelity = result.quasi_dists[0].get(0, 0)
58 
59     """
60 
61     def __init__(
62         self, unitary1: QuantumCircuit, unitary2: QuantumCircuit, prefix1="p1", prefix2="p2"
63     ):
64         """
65         Args:
66             unitary1: Unitary acting on the ket vector.
67             unitary2: Unitary whose inverse operates on the bra vector.
68             prefix1: The name of the parameter vector associated to ``unitary1``,
69                 if it is parameterized. Defaults to ``"p1"``.
70             prefix2: The name of the parameter vector associated to ``unitary2``,
71                 if it is parameterized. Defaults to ``"p2"``.
72 
73         Raises:
74             CircuitError: Number of qubits in ``unitary1`` and ``unitary2`` does not match.
75             CircuitError: Inputs contain measurements and/or resets.
76         """
77         # check inputs are valid
78         if unitary1.num_qubits != unitary2.num_qubits:
79             raise CircuitError(
80                 f"Number of qubits in unitaries does "
81                 f"not match: {unitary1.num_qubits} != {unitary2.num_qubits}."
82             )
83 
84         unitaries = [unitary1, unitary2]
85         for unitary in unitaries:
86             _check_unitary(unitary)
87 
88         # Vectors of new parameters, if any. Need the unitaries in a list here to ensure
89         # we can overwrite them.
90         for i, prefix in enumerate([prefix1, prefix2]):
91             if unitaries[i].num_parameters > 0:
92                 new_params = ParameterVector(prefix, unitaries[i].num_parameters)
93                 unitaries[i] = unitaries[i].assign_parameters(new_params)
94 
95         # Generate the actual overlap circuit
96         super().__init__(unitaries[0].num_qubits, name="UnitaryOverlap")
97         self.compose(unitaries[0], inplace=True)
98         self.compose(unitaries[1].inverse(), inplace=True)
99 
100 
101 def _check_unitary(circuit):
102     """Check a circuit is unitary by checking if all operations are of type ``Gate``."""
103 
104     for instruction in circuit.data:
105         if not isinstance(instruction.operation, (Gate, Barrier)):
106             raise CircuitError(
107                 (
108                     "One or more instructions cannot be converted to"
109                     ' a gate. "{}" is not a gate instruction'
110                 ).format(instruction.operation.name)
111             )
112
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/qiskit/circuit/library/overlap.py b/qiskit/circuit/library/overlap.py
--- a/qiskit/circuit/library/overlap.py
+++ b/qiskit/circuit/library/overlap.py
@@ -59,7 +59,12 @@
     """
 
     def __init__(
-        self, unitary1: QuantumCircuit, unitary2: QuantumCircuit, prefix1="p1", prefix2="p2"
+        self,
+        unitary1: QuantumCircuit,
+        unitary2: QuantumCircuit,
+        prefix1: str = "p1",
+        prefix2: str = "p2",
+        insert_barrier: bool = False,
     ):
         """
         Args:
@@ -69,6 +74,7 @@
                 if it is parameterized. Defaults to ``"p1"``.
             prefix2: The name of the parameter vector associated to ``unitary2``,
                 if it is parameterized. Defaults to ``"p2"``.
+            insert_barrier: Whether to insert a barrier between the two unitaries.
 
         Raises:
             CircuitError: Number of qubits in ``unitary1`` and ``unitary2`` does not match.
@@ -95,6 +101,8 @@
         # Generate the actual overlap circuit
         super().__init__(unitaries[0].num_qubits, name="UnitaryOverlap")
         self.compose(unitaries[0], inplace=True)
+        if insert_barrier:
+            self.barrier()
         self.compose(unitaries[1].inverse(), inplace=True)

{"golden_diff": "diff --git a/qiskit/circuit/library/overlap.py b/qiskit/circuit/library/overlap.py\n--- a/qiskit/circuit/library/overlap.py\n+++ b/qiskit/circuit/library/overlap.py\n@@ -59,7 +59,12 @@\n     \"\"\"\n \n     def __init__(\n-        self, unitary1: QuantumCircuit, unitary2: QuantumCircuit, prefix1=\"p1\", prefix2=\"p2\"\n+        self,\n+        unitary1: QuantumCircuit,\n+        unitary2: QuantumCircuit,\n+        prefix1: str = \"p1\",\n+        prefix2: str = \"p2\",\n+        insert_barrier: bool = False,\n     ):\n         \"\"\"\n         Args:\n@@ -69,6 +74,7 @@\n                 if it is parameterized. Defaults to ``\"p1\"``.\n             prefix2: The name of the parameter vector associated to ``unitary2``,\n                 if it is parameterized. Defaults to ``\"p2\"``.\n+            insert_barrier: Whether to insert a barrier between the two unitaries.\n \n         Raises:\n             CircuitError: Number of qubits in ``unitary1`` and ``unitary2`` does not match.\n@@ -95,6 +101,8 @@\n         # Generate the actual overlap circuit\n         super().__init__(unitaries[0].num_qubits, name=\"UnitaryOverlap\")\n         self.compose(unitaries[0], inplace=True)\n+        if insert_barrier:\n+            self.barrier()\n         self.compose(unitaries[1].inverse(), inplace=True)\n", "issue": "Add insert_barrier argument to UnitaryOverlap\n### What should we add?\n\nThis argument would insert a barrier between the two unitaries. This is useful if you want to prevent circuit optimization between the two parts.\n", "before_files": [{"content": "# This code is part of Qiskit.\n#\n# (C) Copyright IBM 2023.\n#\n# This code is licensed under the Apache License, Version 2.0. You may\n# obtain a copy of this license in the LICENSE.txt file in the root directory\n# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.\n#\n# Any modifications or derivative works of this code must retain this\n# copyright notice, and modified files need to carry a notice indicating\n# that they have been altered from the originals.\n\n\"\"\"Unitary overlap circuit.\"\"\"\n\nfrom qiskit.circuit import QuantumCircuit, Gate\nfrom qiskit.circuit.parametervector import ParameterVector\nfrom qiskit.circuit.exceptions import CircuitError\nfrom qiskit.circuit import Barrier\n\n\nclass UnitaryOverlap(QuantumCircuit):\n    r\"\"\"Circuit that returns the overlap between two unitaries :math:`U_2^{\\dag} U_1`.\n\n    The input quantum circuits must represent unitary operations, since they must be invertible.\n    If the inputs will have parameters, they are replaced by :class:`.ParameterVector`\\s with\n    names `\"p1\"` (for circuit ``unitary1``) and `\"p2\"` (for circuit ``unitary_2``) in the output\n    circuit.\n\n    This circuit is usually employed in computing the fidelity:\n\n    .. math::\n\n        \\left|\\langle 0| U_2^{\\dag} U_1|0\\rangle\\right|^{2}\n\n    by computing the probability of being in the all-zeros bit-string, or equivalently,\n    the expectation value of projector :math:`|0\\rangle\\langle 0|`.\n\n    Example::\n\n        import numpy as np\n        from qiskit.circuit.library import EfficientSU2, UnitaryOverlap\n        from qiskit.primitives import Sampler\n\n        # get two circuit to prepare states of which we comput the overlap\n        circuit = EfficientSU2(2, reps=1)\n        unitary1 = circuit.assign_parameters(np.random.random(circuit.num_parameters))\n        unitary2 = circuit.assign_parameters(np.random.random(circuit.num_parameters))\n\n        # create the overlap circuit\n        overlap = UnitaryOverap(unitary1, unitary2)\n\n        # sample from the overlap\n        sampler = Sampler(options={\"shots\": 100})\n        result = sampler.run(overlap).result()\n\n        # the fidelity is the probability to measure 0\n        fidelity = result.quasi_dists[0].get(0, 0)\n\n    \"\"\"\n\n    def __init__(\n        self, unitary1: QuantumCircuit, unitary2: QuantumCircuit, prefix1=\"p1\", prefix2=\"p2\"\n    ):\n        \"\"\"\n        Args:\n            unitary1: Unitary acting on the ket vector.\n            unitary2: Unitary whose inverse operates on the bra vector.\n            prefix1: The name of the parameter vector associated to ``unitary1``,\n                if it is parameterized. Defaults to ``\"p1\"``.\n            prefix2: The name of the parameter vector associated to ``unitary2``,\n                if it is parameterized. Defaults to ``\"p2\"``.\n\n        Raises:\n            CircuitError: Number of qubits in ``unitary1`` and ``unitary2`` does not match.\n            CircuitError: Inputs contain measurements and/or resets.\n        \"\"\"\n        # check inputs are valid\n        if unitary1.num_qubits != unitary2.num_qubits:\n            raise CircuitError(\n                f\"Number of qubits in unitaries does \"\n                f\"not match: {unitary1.num_qubits} != {unitary2.num_qubits}.\"\n            )\n\n        unitaries = [unitary1, unitary2]\n        for unitary in unitaries:\n            _check_unitary(unitary)\n\n        # Vectors of new parameters, if any. Need the unitaries in a list here to ensure\n        # we can overwrite them.\n        for i, prefix in enumerate([prefix1, prefix2]):\n            if unitaries[i].num_parameters > 0:\n                new_params = ParameterVector(prefix, unitaries[i].num_parameters)\n                unitaries[i] = unitaries[i].assign_parameters(new_params)\n\n        # Generate the actual overlap circuit\n        super().__init__(unitaries[0].num_qubits, name=\"UnitaryOverlap\")\n        self.compose(unitaries[0], inplace=True)\n        self.compose(unitaries[1].inverse(), inplace=True)\n\n\ndef _check_unitary(circuit):\n    \"\"\"Check a circuit is unitary by checking if all operations are of type ``Gate``.\"\"\"\n\n    for instruction in circuit.data:\n        if not isinstance(instruction.operation, (Gate, Barrier)):\n            raise CircuitError(\n                (\n                    \"One or more instructions cannot be converted to\"\n                    ' a gate. \"{}\" is not a gate instruction'\n                ).format(instruction.operation.name)\n            )\n", "path": "qiskit/circuit/library/overlap.py"}], "after_files": [{"content": "# This code is part of Qiskit.\n#\n# (C) Copyright IBM 2023.\n#\n# This code is licensed under the Apache License, Version 2.0. You may\n# obtain a copy of this license in the LICENSE.txt file in the root directory\n# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.\n#\n# Any modifications or derivative works of this code must retain this\n# copyright notice, and modified files need to carry a notice indicating\n# that they have been altered from the originals.\n\n\"\"\"Unitary overlap circuit.\"\"\"\n\nfrom qiskit.circuit import QuantumCircuit, Gate\nfrom qiskit.circuit.parametervector import ParameterVector\nfrom qiskit.circuit.exceptions import CircuitError\nfrom qiskit.circuit import Barrier\n\n\nclass UnitaryOverlap(QuantumCircuit):\n    r\"\"\"Circuit that returns the overlap between two unitaries :math:`U_2^{\\dag} U_1`.\n\n    The input quantum circuits must represent unitary operations, since they must be invertible.\n    If the inputs will have parameters, they are replaced by :class:`.ParameterVector`\\s with\n    names `\"p1\"` (for circuit ``unitary1``) and `\"p2\"` (for circuit ``unitary_2``) in the output\n    circuit.\n\n    This circuit is usually employed in computing the fidelity:\n\n    .. math::\n\n        \\left|\\langle 0| U_2^{\\dag} U_1|0\\rangle\\right|^{2}\n\n    by computing the probability of being in the all-zeros bit-string, or equivalently,\n    the expectation value of projector :math:`|0\\rangle\\langle 0|`.\n\n    Example::\n\n        import numpy as np\n        from qiskit.circuit.library import EfficientSU2, UnitaryOverlap\n        from qiskit.primitives import Sampler\n\n        # get two circuit to prepare states of which we comput the overlap\n        circuit = EfficientSU2(2, reps=1)\n        unitary1 = circuit.assign_parameters(np.random.random(circuit.num_parameters))\n        unitary2 = circuit.assign_parameters(np.random.random(circuit.num_parameters))\n\n        # create the overlap circuit\n        overlap = UnitaryOverap(unitary1, unitary2)\n\n        # sample from the overlap\n        sampler = Sampler(options={\"shots\": 100})\n        result = sampler.run(overlap).result()\n\n        # the fidelity is the probability to measure 0\n        fidelity = result.quasi_dists[0].get(0, 0)\n\n    \"\"\"\n\n    def __init__(\n        self,\n        unitary1: QuantumCircuit,\n        unitary2: QuantumCircuit,\n        prefix1: str = \"p1\",\n        prefix2: str = \"p2\",\n        insert_barrier: bool = False,\n    ):\n        \"\"\"\n        Args:\n            unitary1: Unitary acting on the ket vector.\n            unitary2: Unitary whose inverse operates on the bra vector.\n            prefix1: The name of the parameter vector associated to ``unitary1``,\n                if it is parameterized. Defaults to ``\"p1\"``.\n            prefix2: The name of the parameter vector associated to ``unitary2``,\n                if it is parameterized. Defaults to ``\"p2\"``.\n            insert_barrier: Whether to insert a barrier between the two unitaries.\n\n        Raises:\n            CircuitError: Number of qubits in ``unitary1`` and ``unitary2`` does not match.\n            CircuitError: Inputs contain measurements and/or resets.\n        \"\"\"\n        # check inputs are valid\n        if unitary1.num_qubits != unitary2.num_qubits:\n            raise CircuitError(\n                f\"Number of qubits in unitaries does \"\n                f\"not match: {unitary1.num_qubits} != {unitary2.num_qubits}.\"\n            )\n\n        unitaries = [unitary1, unitary2]\n        for unitary in unitaries:\n            _check_unitary(unitary)\n\n        # Vectors of new parameters, if any. Need the unitaries in a list here to ensure\n        # we can overwrite them.\n        for i, prefix in enumerate([prefix1, prefix2]):\n            if unitaries[i].num_parameters > 0:\n                new_params = ParameterVector(prefix, unitaries[i].num_parameters)\n                unitaries[i] = unitaries[i].assign_parameters(new_params)\n\n        # Generate the actual overlap circuit\n        super().__init__(unitaries[0].num_qubits, name=\"UnitaryOverlap\")\n        self.compose(unitaries[0], inplace=True)\n        if insert_barrier:\n            self.barrier()\n        self.compose(unitaries[1].inverse(), inplace=True)\n\n\ndef _check_unitary(circuit):\n    \"\"\"Check a circuit is unitary by checking if all operations are of type ``Gate``.\"\"\"\n\n    for instruction in circuit.data:\n        if not isinstance(instruction.operation, (Gate, Barrier)):\n            raise CircuitError(\n                (\n                    \"One or more instructions cannot be converted to\"\n                    ' a gate. \"{}\" is not a gate instruction'\n                ).format(instruction.operation.name)\n            )\n", "path": "qiskit/circuit/library/overlap.py"}]}