From 6dbd864142c021d763cf610826c1cf6bbdd63293 Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Mon, 13 Nov 2023 11:22:05 +0400
Subject: [PATCH 01/10] test transpiler and measurements

---
 src/qibo/transpiler/test_m.py | 38 +++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 src/qibo/transpiler/test_m.py

diff --git a/src/qibo/transpiler/test_m.py b/src/qibo/transpiler/test_m.py
new file mode 100644
index 0000000000..29a45248f4
--- /dev/null
+++ b/src/qibo/transpiler/test_m.py
@@ -0,0 +1,38 @@
+import networkx as nx
+
+import qibo
+from qibo import gates
+from qibo.models import Circuit
+from qibo.transpiler.placer import Trivial
+from qibo.transpiler.router import Sabre
+
+# new_gate = gates.M(*qubits, **gate.init_kwargs)
+# new_gate.result = gate.result
+# new.add(new_gate)
+
+measurement = gates.M(0, register_name="a")
+measurement2 = gates.M(1, register_name="b")
+
+circ = Circuit(3)
+circ.add(gates.H(0))
+circ.add(measurement)
+circ.add(measurement2)
+
+circ2 = Circuit(3)
+for gate in circ.queue:
+    circ2.add(gate)
+
+connectivity = nx.Graph()
+connectivity.add_nodes_from([0, 1, 2])
+connectivity.add_edges_from([(0, 1), (1, 2)])
+router = Sabre(connectivity=connectivity)
+initial_layout = {"q0": 0, "q1": 1, "q2": 2}
+
+routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
+
+result2 = routed_circ.execute(nshots=100)
+# result2 = circ2.execute(nshots=100)
+print(result2.frequencies())
+
+print(measurement.result.has_samples())
+print(measurement.result.frequencies())

From e4880acb13cad0192f556ec063e1763a5d2795f6 Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Mon, 13 Nov 2023 17:37:25 +0400
Subject: [PATCH 02/10] modify block.on_qubits

---
 src/qibo/transpiler/blocks.py |  8 ++++++--
 src/qibo/transpiler/test_m.py | 12 +++++++-----
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/qibo/transpiler/blocks.py b/src/qibo/transpiler/blocks.py
index 7c0ec3d902..b7e5b9d501 100644
--- a/src/qibo/transpiler/blocks.py
+++ b/src/qibo/transpiler/blocks.py
@@ -77,8 +77,12 @@ def on_qubits(self, new_qubits: tuple):
             new_qubits (tuple): new qubits where the block is acting.
         """
         qubits_dict = dict(zip(self.qubits, new_qubits))
-        new_gates = [gate.on_qubits(qubits_dict) for gate in self.gates]
-
+        new_gates = []
+        for gate in self.gates:
+            new_gate = gate.on_qubits(qubits_dict)
+            if isinstance(gate, gates.M):
+                new_gate.result = gate.result
+            new_gates.append(new_gate)
         return Block(qubits=new_qubits, gates=new_gates, name=self.name)
 
     # TODO: use real QM properties to check commutation
diff --git a/src/qibo/transpiler/test_m.py b/src/qibo/transpiler/test_m.py
index 29a45248f4..e093bed0cb 100644
--- a/src/qibo/transpiler/test_m.py
+++ b/src/qibo/transpiler/test_m.py
@@ -14,13 +14,14 @@
 measurement2 = gates.M(1, register_name="b")
 
 circ = Circuit(3)
-circ.add(gates.H(0))
 circ.add(measurement)
 circ.add(measurement2)
 
+new_measurement = measurement.on_qubits({0: 1})
+new_measurement.result = measurement.result
 circ2 = Circuit(3)
-for gate in circ.queue:
-    circ2.add(gate)
+circ2.add(gates.H(0))
+circ2.add(new_measurement)
 
 connectivity = nx.Graph()
 connectivity.add_nodes_from([0, 1, 2])
@@ -33,6 +34,7 @@
 result2 = routed_circ.execute(nshots=100)
 # result2 = circ2.execute(nshots=100)
 print(result2.frequencies())
-
-print(measurement.result.has_samples())
+# print(result2.has_samples())
+# print(measurement.result.has_samples())
 print(measurement.result.frequencies())
+# print(measurement.result.has_samples())

From a375259ffca2b910270d98d2047aecbdd9ecd6ef Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Mon, 13 Nov 2023 17:49:07 +0400
Subject: [PATCH 03/10] add test of sabre with measurements

---
 tests/test_transpiler_router.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/test_transpiler_router.py b/tests/test_transpiler_router.py
index 146e11b849..6ce80ada29 100644
--- a/tests/test_transpiler_router.py
+++ b/tests/test_transpiler_router.py
@@ -331,3 +331,17 @@ def test_sabre_memory_map():
     router._memory_map = [[1, 0, 2, 3, 4]]
     value = router._compute_cost((0, 1))
     assert value == float("inf")
+
+
+def test_sabre_measurements():
+    measurement = gates.M(0)
+    circ = Circuit(3)
+    circ.add(measurement)
+    connectivity = nx.Graph()
+    connectivity.add_nodes_from([0, 1, 2])
+    connectivity.add_edges_from([(0, 1), (1, 2)])
+    router = Sabre(connectivity=connectivity)
+    initial_layout = {"q0": 0, "q1": 1, "q2": 2}
+    routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
+    circuit_result = routed_circ.execute(nshots=100)
+    assert circuit_result.frequencies() == measurement.result.frequencies()

From c13deeb810e52d8d815c2b2a415e6886ee70f50e Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Tue, 14 Nov 2023 16:55:17 +0400
Subject: [PATCH 04/10] overload on_qubits for measurements

---
 src/qibo/gates/measurements.py | 36 ++++++++++++++++++++++++++++++++++
 src/qibo/transpiler/blocks.py  |  7 +------
 2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/src/qibo/gates/measurements.py b/src/qibo/gates/measurements.py
index 58aa32842f..20bfa94925 100644
--- a/src/qibo/gates/measurements.py
+++ b/src/qibo/gates/measurements.py
@@ -211,3 +211,39 @@ def load(cls, payload):
         args["basis"] = [getattr(gates, g) for g in args["basis"]]
         args.update(args.pop("init_kwargs"))
         return cls(*qubits, **args)
+
+    # Overload on_qubits to copy also gate.result, controlled by can be removed for measurements
+    def on_qubits(self, qubit_map) -> "Gate":
+        """Creates the same gate targeting different qubits.
+
+        Args:
+            qubit_map (int): Dictionary mapping original qubit indices to new ones.
+
+        Returns:
+            A :class:`qibo.gates.Gate` object of the original gate
+            type targeting the given qubits.
+
+        Example:
+
+            .. testcode::
+
+                from qibo import models, gates
+                c = models.Circuit(4)
+                # Add some CNOT gates
+                c.add(gates.CNOT(2, 3).on_qubits({2: 2, 3: 3})) # equivalent to gates.CNOT(2, 3)
+                c.add(gates.CNOT(2, 3).on_qubits({2: 3, 3: 0})) # equivalent to gates.CNOT(3, 0)
+                c.add(gates.CNOT(2, 3).on_qubits({2: 1, 3: 3})) # equivalent to gates.CNOT(1, 3)
+                c.add(gates.CNOT(2, 3).on_qubits({2: 2, 3: 1})) # equivalent to gates.CNOT(2, 1)
+                print(c.draw())
+            .. testoutput::
+
+                q0: ───X─────
+                q1: ───|─o─X─
+                q2: ─o─|─|─o─
+                q3: ─X─o─X───
+        """
+
+        qubits = (qubit_map.get(q) for q in self.qubits)
+        gate = self.__class__(*qubits, **self.init_kwargs)
+        gate.result = self.result
+        return gate
diff --git a/src/qibo/transpiler/blocks.py b/src/qibo/transpiler/blocks.py
index b7e5b9d501..658552fb06 100644
--- a/src/qibo/transpiler/blocks.py
+++ b/src/qibo/transpiler/blocks.py
@@ -77,12 +77,7 @@ def on_qubits(self, new_qubits: tuple):
             new_qubits (tuple): new qubits where the block is acting.
         """
         qubits_dict = dict(zip(self.qubits, new_qubits))
-        new_gates = []
-        for gate in self.gates:
-            new_gate = gate.on_qubits(qubits_dict)
-            if isinstance(gate, gates.M):
-                new_gate.result = gate.result
-            new_gates.append(new_gate)
+        new_gates = [gate.on_qubits(qubits_dict) for gate in self.gates]
         return Block(qubits=new_qubits, gates=new_gates, name=self.name)
 
     # TODO: use real QM properties to check commutation

From b7eb8d514e15e690021370fd92e29aed0b18981c Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Wed, 15 Nov 2023 14:27:16 +0400
Subject: [PATCH 05/10] completed

---
 src/qibo/transpiler/blocks.py   | 15 +++++---
 src/qibo/transpiler/router.py   | 62 ++++++++++++++++++++++++++++++---
 src/qibo/transpiler/test_m.py   | 40 ---------------------
 tests/test_transpiler_router.py | 23 ++++++++++--
 4 files changed, 89 insertions(+), 51 deletions(-)
 delete mode 100644 src/qibo/transpiler/test_m.py

diff --git a/src/qibo/transpiler/blocks.py b/src/qibo/transpiler/blocks.py
index 658552fb06..764213e62f 100644
--- a/src/qibo/transpiler/blocks.py
+++ b/src/qibo/transpiler/blocks.py
@@ -101,7 +101,7 @@ def kak_decompose(self):  # pragma: no cover
         This should be done only if the block is entangled and the number of
         two qubit gates is higher than the number after the decomposition.
         """
-        raise_error(NotImplementedError, "")
+        raise_error(NotImplementedError, "KAK decomposition is not available yet.")
 
 
 class CircuitBlocks:
@@ -144,9 +144,16 @@ def add_block(self, block: "Block"):
             )
         self.block_list.append(block)
 
-    def circuit(self):
-        """Return the quantum circuit."""
-        circuit = Circuit(self.qubits)
+    def circuit(self, circuit_kwargs=None):
+        """Return the quantum circuit.
+
+        Args:
+            circuit_kwargs (dict): original circuit init_kwargs.
+        """
+        if circuit_kwargs is None:
+            circuit = Circuit(self.qubits)
+        else:
+            circuit = Circuit(**circuit_kwargs)
         for block in self.block_list:
             for gate in block.gates:
                 circuit.add(gate)
diff --git a/src/qibo/transpiler/router.py b/src/qibo/transpiler/router.py
index ebc6571252..08d3af6f3e 100644
--- a/src/qibo/transpiler/router.py
+++ b/src/qibo/transpiler/router.py
@@ -371,9 +371,13 @@ def execute_block(self, block: Block):
         self._routed_blocks.add_block(block.on_qubits(self.get_physical_qubits(block)))
         self.circuit_blocks.remove_block(block)
 
-    def routed_circuit(self):
-        """Returns circuit of the routed circuit."""
-        return self._routed_blocks.circuit()
+    def routed_circuit(self, circuit_kwargs=None):
+        """Returns circuit of the routed circuit.
+
+        Args:
+            circuit_kwargs (dict): original circuit init_kwargs.
+        """
+        return self._routed_blocks.circuit(circuit_kwargs=circuit_kwargs)
 
     def final_layout(self):
         """Returns the final physical-circuit qubits mapping."""
@@ -455,6 +459,7 @@ def __init__(
         self._front_layer = None
         self.circuit = None
         self._memory_map = None
+        self._final_measurements = None
         random.seed(seed)
 
     def __call__(self, circuit: Circuit, initial_layout: dict):
@@ -475,7 +480,13 @@ def __call__(self, circuit: Circuit, initial_layout: dict):
             else:
                 self._find_new_mapping()
 
-        return self.circuit.routed_circuit(), self.circuit.final_layout()
+        routed_circuit = self.circuit.routed_circuit(circuit_kwargs=circuit.init_kwargs)
+        if self._final_measurements is not None:
+            routed_circuit = self._append_final_measurements(
+                routed_circuit=routed_circuit
+            )
+
+        return routed_circuit, self.circuit.final_layout()
 
     @property
     def added_swaps(self):
@@ -485,6 +496,7 @@ def added_swaps(self):
     def _preprocessing(self, circuit: Circuit, initial_layout: dict):
         """The following objects will be initialised:
         - circuit: class to represent circuit and to perform logical-physical qubit mapping.
+        - _final_measurements: measurement gates at the end of the circuit.
         - _dist_matrix: matrix reporting the shortest path lengh between all node pairs.
         - _dag: direct acyclic graph of the circuit based on commutativity.
         - _memory_map: list to remember previous SWAP moves.
@@ -492,7 +504,9 @@ def _preprocessing(self, circuit: Circuit, initial_layout: dict):
         - _delta_register: list containing the special weigh added to qubits
             to prevent overlapping swaps.
         """
-        self.circuit = CircuitMap(initial_layout, circuit)
+        copy_circuit = self._copy_circuit(circuit)
+        self._final_measurements = self._detach_final_measurements(copy_circuit)
+        self.circuit = CircuitMap(initial_layout, copy_circuit)
         self._dist_matrix = nx.floyd_warshall_numpy(self.connectivity)
         self._dag = _create_dag(self.circuit.blocks_qubits_pairs())
         self._memory_map = []
@@ -500,7 +514,45 @@ def _preprocessing(self, circuit: Circuit, initial_layout: dict):
         self._update_front_layer()
         self._delta_register = [1.0 for _ in range(circuit.nqubits)]
 
+    @staticmethod
+    def _copy_circuit(circuit: Circuit):
+        """Return a copy of the circuit to avoid altering the original circuit.
+        This copy conserves the registers of the measurement gates."""
+        new_circuit = Circuit(circuit.nqubits)
+        for gate in circuit.queue:
+            new_circuit.add(gate)
+        return new_circuit
+
+    def _detach_final_measurements(self, circuit: Circuit):
+        """Detach measurement gates at the end of the circuit for separate handling."""
+        final_measurements = []
+        reversed_queue = circuit.queue[::-1]
+        for gate in reversed_queue:
+            if isinstance(gate, gates.M):
+                final_measurements.append(gate)
+                circuit.queue.remove(gate)
+            else:
+                break
+        print(final_measurements)
+        if len(final_measurements) == 0:
+            return None
+        return final_measurements[::-1]
+
+    def _append_final_measurements(self, routed_circuit: Circuit):
+        """Append the final measurment gates on the correct qubits conserving the measurement register."""
+        for measurement in self._final_measurements:
+            print(measurement)
+            original_qubits = measurement.qubits
+            routed_qubits = (
+                self.circuit.circuit_to_physical(qubit) for qubit in original_qubits
+            )
+            routed_circuit.add(
+                measurement.on_qubits(dict(zip(original_qubits, routed_qubits)))
+            )
+        return routed_circuit
+
     def _update_dag_layers(self):
+        """Update dag layers and put them in topological order."""
         for layer, nodes in enumerate(nx.topological_generations(self._dag)):
             for node in nodes:
                 self._dag.nodes[node]["layer"] = layer
diff --git a/src/qibo/transpiler/test_m.py b/src/qibo/transpiler/test_m.py
deleted file mode 100644
index e093bed0cb..0000000000
--- a/src/qibo/transpiler/test_m.py
+++ /dev/null
@@ -1,40 +0,0 @@
-import networkx as nx
-
-import qibo
-from qibo import gates
-from qibo.models import Circuit
-from qibo.transpiler.placer import Trivial
-from qibo.transpiler.router import Sabre
-
-# new_gate = gates.M(*qubits, **gate.init_kwargs)
-# new_gate.result = gate.result
-# new.add(new_gate)
-
-measurement = gates.M(0, register_name="a")
-measurement2 = gates.M(1, register_name="b")
-
-circ = Circuit(3)
-circ.add(measurement)
-circ.add(measurement2)
-
-new_measurement = measurement.on_qubits({0: 1})
-new_measurement.result = measurement.result
-circ2 = Circuit(3)
-circ2.add(gates.H(0))
-circ2.add(new_measurement)
-
-connectivity = nx.Graph()
-connectivity.add_nodes_from([0, 1, 2])
-connectivity.add_edges_from([(0, 1), (1, 2)])
-router = Sabre(connectivity=connectivity)
-initial_layout = {"q0": 0, "q1": 1, "q2": 2}
-
-routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
-
-result2 = routed_circ.execute(nshots=100)
-# result2 = circ2.execute(nshots=100)
-print(result2.frequencies())
-# print(result2.has_samples())
-# print(measurement.result.has_samples())
-print(measurement.result.frequencies())
-# print(measurement.result.has_samples())
diff --git a/tests/test_transpiler_router.py b/tests/test_transpiler_router.py
index 6ce80ada29..d5a667fab4 100644
--- a/tests/test_transpiler_router.py
+++ b/tests/test_transpiler_router.py
@@ -246,7 +246,7 @@ def test_circuit_map():
     circuit_map.execute_block(block_list.search_by_index(1))
     circuit_map.execute_block(block_list.search_by_index(2))
     circuit_map.execute_block(block_list.search_by_index(3))
-    routed_circuit = circuit_map.routed_circuit()
+    routed_circuit = circuit_map.routed_circuit(circuit_kwargs=None)
     assert isinstance(routed_circuit.queue[6], gates.CZ)
     # circuit to logical map: [1,2,0,3]. initial map: {"q0": 2, "q1": 0, "q2": 1, "q3": 3}.
     assert routed_circuit.queue[6].qubits == (0, 1)  # initial circuit qubits (1,2)
@@ -333,9 +333,27 @@ def test_sabre_memory_map():
     assert value == float("inf")
 
 
-def test_sabre_measurements():
+def test_sabre_intermediate_measurements():
     measurement = gates.M(0)
+    circ = Circuit(3, density_matrix=True)
+    circ.add(gates.H(0))
+    circ.add(measurement)
+    circ.add(gates.CNOT(0, 1))
+    connectivity = nx.Graph()
+    connectivity.add_nodes_from([0, 1, 2])
+    connectivity.add_edges_from([(0, 1), (1, 2)])
+    router = Sabre(connectivity=connectivity)
+    initial_layout = {"q0": 0, "q1": 1, "q2": 2}
+    routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
+    circuit_result = routed_circ.execute(nshots=100)
+    assert routed_circ.queue[1].result is measurement.result
+
+
+def test_sabre_final_measurements():
+    measurement = gates.M(0, 1, 2)
     circ = Circuit(3)
+    circ.add(gates.H(0))
+    circ.add(gates.CNOT(0, 2))
     circ.add(measurement)
     connectivity = nx.Graph()
     connectivity.add_nodes_from([0, 1, 2])
@@ -345,3 +363,4 @@ def test_sabre_measurements():
     routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
     circuit_result = routed_circ.execute(nshots=100)
     assert circuit_result.frequencies() == measurement.result.frequencies()
+    assert routed_circ.queue[-1].result is measurement.result

From 3584b366beb96a80b545a389202ac032ac5bf949 Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Wed, 15 Nov 2023 14:34:56 +0400
Subject: [PATCH 06/10] remove prints

---
 src/qibo/transpiler/router.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/qibo/transpiler/router.py b/src/qibo/transpiler/router.py
index 08d3af6f3e..d61d98bdd6 100644
--- a/src/qibo/transpiler/router.py
+++ b/src/qibo/transpiler/router.py
@@ -533,7 +533,6 @@ def _detach_final_measurements(self, circuit: Circuit):
                 circuit.queue.remove(gate)
             else:
                 break
-        print(final_measurements)
         if len(final_measurements) == 0:
             return None
         return final_measurements[::-1]
@@ -541,7 +540,6 @@ def _detach_final_measurements(self, circuit: Circuit):
     def _append_final_measurements(self, routed_circuit: Circuit):
         """Append the final measurment gates on the correct qubits conserving the measurement register."""
         for measurement in self._final_measurements:
-            print(measurement)
             original_qubits = measurement.qubits
             routed_qubits = (
                 self.circuit.circuit_to_physical(qubit) for qubit in original_qubits

From 11f50a3054fae5f42a79f3b80abb728b39b8ab4f Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Thu, 16 Nov 2023 11:15:36 +0400
Subject: [PATCH 07/10] corrections by andrea

---
 src/qibo/gates/measurements.py  | 22 ++++++++++------------
 src/qibo/transpiler/router.py   |  7 +++----
 tests/test_transpiler_router.py |  2 +-
 3 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/qibo/gates/measurements.py b/src/qibo/gates/measurements.py
index 20bfa94925..ec5bcb0b43 100644
--- a/src/qibo/gates/measurements.py
+++ b/src/qibo/gates/measurements.py
@@ -214,13 +214,14 @@ def load(cls, payload):
 
     # Overload on_qubits to copy also gate.result, controlled by can be removed for measurements
     def on_qubits(self, qubit_map) -> "Gate":
-        """Creates the same gate targeting different qubits.
+        """Creates the same measurement gate targeting different qubits
+        and preserving the measurement result register.
 
         Args:
             qubit_map (int): Dictionary mapping original qubit indices to new ones.
 
         Returns:
-            A :class:`qibo.gates.Gate` object of the original gate
+            A :class:`qibo.gates.Gate.M` object of the original gate
             type targeting the given qubits.
 
         Example:
@@ -228,19 +229,16 @@ def on_qubits(self, qubit_map) -> "Gate":
             .. testcode::
 
                 from qibo import models, gates
-                c = models.Circuit(4)
-                # Add some CNOT gates
-                c.add(gates.CNOT(2, 3).on_qubits({2: 2, 3: 3})) # equivalent to gates.CNOT(2, 3)
-                c.add(gates.CNOT(2, 3).on_qubits({2: 3, 3: 0})) # equivalent to gates.CNOT(3, 0)
-                c.add(gates.CNOT(2, 3).on_qubits({2: 1, 3: 3})) # equivalent to gates.CNOT(1, 3)
-                c.add(gates.CNOT(2, 3).on_qubits({2: 2, 3: 1})) # equivalent to gates.CNOT(2, 1)
+                measurement = gates.M(0, 1)
+                c = models.Circuit(3)
+                c.add(measurement.on_qubits({0: 0, 1: 2}))
+                assert c.queue[0].result is measurement.result
                 print(c.draw())
             .. testoutput::
 
-                q0: ───X─────
-                q1: ───|─o─X─
-                q2: ─o─|─|─o─
-                q3: ─X─o─X───
+                q0: ─M─
+                q1: ─|─
+                q2: ─M─
         """
 
         qubits = (qubit_map.get(q) for q in self.qubits)
diff --git a/src/qibo/transpiler/router.py b/src/qibo/transpiler/router.py
index d61d98bdd6..d15194b9e3 100644
--- a/src/qibo/transpiler/router.py
+++ b/src/qibo/transpiler/router.py
@@ -372,7 +372,7 @@ def execute_block(self, block: Block):
         self.circuit_blocks.remove_block(block)
 
     def routed_circuit(self, circuit_kwargs=None):
-        """Returns circuit of the routed circuit.
+        """Return the routed circuit.
 
         Args:
             circuit_kwargs (dict): original circuit init_kwargs.
@@ -526,14 +526,13 @@ def _copy_circuit(circuit: Circuit):
     def _detach_final_measurements(self, circuit: Circuit):
         """Detach measurement gates at the end of the circuit for separate handling."""
         final_measurements = []
-        reversed_queue = circuit.queue[::-1]
-        for gate in reversed_queue:
+        for gate in circuit.queue[::-1]:
             if isinstance(gate, gates.M):
                 final_measurements.append(gate)
                 circuit.queue.remove(gate)
             else:
                 break
-        if len(final_measurements) == 0:
+        if not final_measurements:
             return None
         return final_measurements[::-1]
 
diff --git a/tests/test_transpiler_router.py b/tests/test_transpiler_router.py
index d5a667fab4..d9d513bf35 100644
--- a/tests/test_transpiler_router.py
+++ b/tests/test_transpiler_router.py
@@ -246,7 +246,7 @@ def test_circuit_map():
     circuit_map.execute_block(block_list.search_by_index(1))
     circuit_map.execute_block(block_list.search_by_index(2))
     circuit_map.execute_block(block_list.search_by_index(3))
-    routed_circuit = circuit_map.routed_circuit(circuit_kwargs=None)
+    routed_circuit = circuit_map.routed_circuit()
     assert isinstance(routed_circuit.queue[6], gates.CZ)
     # circuit to logical map: [1,2,0,3]. initial map: {"q0": 2, "q1": 0, "q2": 1, "q3": 3}.
     assert routed_circuit.queue[6].qubits == (0, 1)  # initial circuit qubits (1,2)

From 3b4bdbc32890b55a18b5ba076a9220d91a6de297 Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Mon, 20 Nov 2023 12:07:36 +0400
Subject: [PATCH 08/10] corrected issue with intermediate measurements

---
 src/qibo/transpiler/router.py   | 20 +++++++++++++++++---
 tests/test_transpiler_router.py | 32 ++++++++++----------------------
 2 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/src/qibo/transpiler/router.py b/src/qibo/transpiler/router.py
index d15194b9e3..d0a32e23d9 100644
--- a/src/qibo/transpiler/router.py
+++ b/src/qibo/transpiler/router.py
@@ -351,15 +351,24 @@ class CircuitMap:
     Args:
         initial_layout (dict): initial logical-to-physical qubit mapping.
         circuit (Circuit): circuit to be routed.
+        blocks (CircuitBlocks): circuit blocks representation, if None the blocks will be computed from the circuit.
     """
 
-    def __init__(self, initial_layout: dict, circuit: Circuit):
-        self.circuit_blocks = CircuitBlocks(circuit, index_names=True)
+    def __init__(self, initial_layout: dict, circuit: Circuit, blocks=None):
+        if blocks is not None:
+            self.circuit_blocks = blocks
+        else:
+            self.circuit_blocks = CircuitBlocks(circuit, index_names=True)
+        self.initial_layout = initial_layout
         self._circuit_logical = list(range(len(initial_layout)))
         self._physical_logical = list(initial_layout.values())
         self._routed_blocks = CircuitBlocks(Circuit(circuit.nqubits))
         self._swaps = 0
 
+    def set_circuit_logical(self, circuit_logical_map: list):
+        """Set the current circuit to logical qubit mapping."""
+        self._circuit_logical = circuit_logical_map
+
     def blocks_qubits_pairs(self):
         """Returns a list containing the qubit pairs of each block."""
         return [block.qubits for block in self.circuit_blocks()]
@@ -579,7 +588,12 @@ def _find_new_mapping(self):
 
     def _compute_cost(self, candidate):
         """Compute the cost associated to a possible SWAP candidate."""
-        temporary_circuit = deepcopy(self.circuit)
+        temporary_circuit = CircuitMap(
+            initial_layout=self.circuit.initial_layout,
+            circuit=Circuit(len(self.circuit.initial_layout)),
+            blocks=self.circuit.circuit_blocks,
+        )
+        temporary_circuit.set_circuit_logical(deepcopy(self.circuit._circuit_logical))
         temporary_circuit.update(candidate)
         if temporary_circuit._circuit_logical in self._memory_map:
             return float("inf")
diff --git a/tests/test_transpiler_router.py b/tests/test_transpiler_router.py
index d9d513bf35..2a950f05b8 100644
--- a/tests/test_transpiler_router.py
+++ b/tests/test_transpiler_router.py
@@ -298,28 +298,33 @@ def test_sabre_simple(seed):
     )
 
 
-@pytest.mark.parametrize("gates", [10, 40])
+@pytest.mark.parametrize("n_gates", [10, 40])
 @pytest.mark.parametrize("look", [0, 5])
 @pytest.mark.parametrize("decay", [0.5, 1.0])
 @pytest.mark.parametrize("placer", [Trivial, Random])
 @pytest.mark.parametrize("connectivity", [star_connectivity(), grid_connectivity()])
-def test_sabre_random_circuits(gates, look, decay, placer, connectivity):
+def test_sabre_random_circuits(n_gates, look, decay, placer, connectivity):
     placer = placer(connectivity=connectivity)
     layout_circ = Circuit(5)
     initial_layout = placer(layout_circ)
     router = Sabre(connectivity=connectivity, lookahead=look, decay_lookahead=decay)
-    circuit = generate_random_circuit(nqubits=5, ngates=gates)
+    circuit = generate_random_circuit(nqubits=5, ngates=n_gates)
+    measurement = gates.M(*range(5))
+    circuit.add(measurement)
     transpiled_circuit, final_qubit_map = router(circuit, initial_layout)
     assert router.added_swaps >= 0
     assert_connectivity(connectivity, transpiled_circuit)
     assert_placement(transpiled_circuit, final_qubit_map)
-    assert gates + router.added_swaps == transpiled_circuit.ngates
+    assert n_gates + router.added_swaps + 1 == transpiled_circuit.ngates
     assert_circuit_equivalence(
         original_circuit=circuit,
         transpiled_circuit=transpiled_circuit,
         final_map=final_qubit_map,
         initial_map=initial_layout,
     )
+    circuit_result = transpiled_circuit.execute(nshots=100)
+    assert circuit_result.frequencies() == measurement.result.frequencies()
+    assert transpiled_circuit.queue[-1].result is measurement.result
 
 
 def test_sabre_memory_map():
@@ -338,23 +343,7 @@ def test_sabre_intermediate_measurements():
     circ = Circuit(3, density_matrix=True)
     circ.add(gates.H(0))
     circ.add(measurement)
-    circ.add(gates.CNOT(0, 1))
-    connectivity = nx.Graph()
-    connectivity.add_nodes_from([0, 1, 2])
-    connectivity.add_edges_from([(0, 1), (1, 2)])
-    router = Sabre(connectivity=connectivity)
-    initial_layout = {"q0": 0, "q1": 1, "q2": 2}
-    routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
-    circuit_result = routed_circ.execute(nshots=100)
-    assert routed_circ.queue[1].result is measurement.result
-
-
-def test_sabre_final_measurements():
-    measurement = gates.M(0, 1, 2)
-    circ = Circuit(3)
-    circ.add(gates.H(0))
     circ.add(gates.CNOT(0, 2))
-    circ.add(measurement)
     connectivity = nx.Graph()
     connectivity.add_nodes_from([0, 1, 2])
     connectivity.add_edges_from([(0, 1), (1, 2)])
@@ -362,5 +351,4 @@ def test_sabre_final_measurements():
     initial_layout = {"q0": 0, "q1": 1, "q2": 2}
     routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
     circuit_result = routed_circ.execute(nshots=100)
-    assert circuit_result.frequencies() == measurement.result.frequencies()
-    assert routed_circ.queue[-1].result is measurement.result
+    assert routed_circ.queue[2].result is measurement.result

From 23cd8689ce4221ef7ad5ffa8b4a32689c34f1332 Mon Sep 17 00:00:00 2001
From: Andrea Papaluca <andreapapaluca@gmail.com>
Date: Mon, 20 Nov 2023 13:53:34 +0400
Subject: [PATCH 09/10] moved measurement

---
 tests/test_transpiler_router.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/test_transpiler_router.py b/tests/test_transpiler_router.py
index 2a950f05b8..d991c7dd45 100644
--- a/tests/test_transpiler_router.py
+++ b/tests/test_transpiler_router.py
@@ -339,7 +339,7 @@ def test_sabre_memory_map():
 
 
 def test_sabre_intermediate_measurements():
-    measurement = gates.M(0)
+    measurement = gates.M(1)
     circ = Circuit(3, density_matrix=True)
     circ.add(gates.H(0))
     circ.add(measurement)

From 053c803abcf810a33c00e10e89a4803df2146893 Mon Sep 17 00:00:00 2001
From: simone bordoni <simone.bordoni@uniroma1.it>
Date: Tue, 21 Nov 2023 11:10:01 +0400
Subject: [PATCH 10/10] fixed tests

---
 tests/test_transpiler_router.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/test_transpiler_router.py b/tests/test_transpiler_router.py
index d991c7dd45..28a0c9b15f 100644
--- a/tests/test_transpiler_router.py
+++ b/tests/test_transpiler_router.py
@@ -351,4 +351,4 @@ def test_sabre_intermediate_measurements():
     initial_layout = {"q0": 0, "q1": 1, "q2": 2}
     routed_circ, final_layout = router(circuit=circ, initial_layout=initial_layout)
     circuit_result = routed_circ.execute(nshots=100)
-    assert routed_circ.queue[2].result is measurement.result
+    assert routed_circ.queue[3].result is measurement.result