feat: Use one register per vertex

pytket-mbqc-py/pytket_mbqc_py/__init__.py

@@ -5,4 +5,3 @@
 from .cnot_block import CNOTBlocksGraphCircuit
 from .graph_circuit import GraphCircuit
 from .qubit_manager import QubitManager
-from .random_register_manager import RandomRegisterManager

pytket-mbqc-py/pytket_mbqc_py/qubit_manager.py

@@ -6,7 +6,7 @@
 from typing import Dict, List
 
 from pytket import Circuit
-from pytket.unit_id import BitRegister, Qubit
+from pytket.unit_id import Bit, Qubit
 
 
 class QubitManager(Circuit):
@@ -20,16 +20,12 @@ class QubitManager(Circuit):
         These are those qubits which have either never been used, or have been
         used but have been measured and can be reset.
     :ivar all_qubit_list: All qubits which could in principle be used.
-    :ivar qubit_meas_reg: A dictionary mapping qubits to the
-        classical registers where their measurement results
-        will be stored.
     :ivar physical_qubits_used: A set containing the qubits which
         have been made use of at some point.
     """
 
     available_qubit_list: List[Qubit]
     all_qubit_list: List[Qubit]
-    qubit_meas_reg: Dict[Qubit, BitRegister]
     physical_qubits_used: set[Qubit]
 
     def __init__(self, n_physical_qubits: int) -> None:
@@ -41,21 +37,15 @@ def __init__(self, n_physical_qubits: int) -> None:
         """
         self.available_qubit_list = [Qubit(index=i) for i in range(n_physical_qubits)]
         self.all_qubit_list = [Qubit(index=i) for i in range(n_physical_qubits)]
-        self.qubit_meas_reg = {
-            qubit: BitRegister(name=f"meas_{i}", size=1)
-            for i, qubit in enumerate(self.available_qubit_list)
-        }
+        self.qubit_meas_bit: Dict[Qubit, Bit] = dict()
         self.physical_qubits_used = set()
 
         super().__init__()
 
-        for meas_reg in self.qubit_meas_reg.values():
-            self.add_c_register(register=meas_reg)
-
         for qubit in self.all_qubit_list:
             self.add_qubit(id=qubit)
 
-    def get_qubit(self) -> Qubit:
+    def get_qubit(self, measure_bit: Bit) -> Qubit:
         """Return a qubit which is not in use, and which
         is included in the underlying circuit.
 
@@ -67,7 +57,8 @@ def get_qubit(self) -> Qubit:
 
         qubit = self.available_qubit_list.pop(0)
         self.physical_qubits_used.add(qubit)
-        self.add_c_setreg(0, self.qubit_meas_reg[qubit])
+        self.qubit_meas_bit[qubit] = measure_bit
+        self.add_c_setbits([False], [self.qubit_meas_bit[qubit]])
         self.Reset(qubit=qubit)
 
         return qubit
@@ -93,4 +84,4 @@ def managed_measure(self, qubit: Qubit) -> None:
                 + "get_qubit method."
             )
         self.available_qubit_list.insert(0, qubit)
-        self.Measure(qubit=qubit, bit=self.qubit_meas_reg[qubit][0])
+        self.Measure(qubit=qubit, bit=self.qubit_meas_bit[qubit])

pytket-mbqc-py/source/index.rst

@@ -11,7 +11,6 @@ Welcome to pytket-mbqc's documentation!
    :caption: Contents:
 
    qubit_manager
-   random_register_manager
    graph_circuit
 
 

pytket-mbqc-py/tests/test_graph_circuit.py

@@ -645,7 +645,7 @@ def test_cnot_entangled_output(input_state, output_state):
 
     with pytest.raises(
         Exception,
-        match="Too many initialisation registers, 4, were created. Consider setting n_logical_qubits=3 upon initialising this class.",
+        match="Too many vertex registers, 4, were created. Consider setting n_logical_qubits=3 upon initialising this class.",
     ):
         graph_circuit.get_outputs()
 
@@ -802,3 +802,67 @@ def test_single_unmeasured_vertex():
 
     graph_circuit.add_graph_vertex(measurement_order=None)
     assert graph_circuit.get_outputs() == {0: Qubit(1)}
+
+
+def test_too_few_qubits():
+    circuit = GraphCircuit(
+        n_physical_qubits=2,
+        n_logical_qubits=2,
+    )
+    reg = circuit.add_c_register(
+        name="my_reg",
+        size=3,
+    )
+    circuit.get_qubit(reg[0])
+    circuit.get_qubit(reg[1])
+
+    with pytest.raises(
+        Exception,
+        match="You have run out of qubits.",
+    ):
+        circuit.get_qubit(reg[2])
+
+    with pytest.raises(
+        Exception,
+        match="There are no unused qubits which can be used to generate randomness.",
+    ):
+        circuit.populate_random_bits(
+            bit_list=reg[2],
+        )
+
+
+def test_randomness_generation():
+    circuit = GraphCircuit(
+        n_physical_qubits=3,
+        n_logical_qubits=2,
+    )
+
+    reg_one = circuit.add_c_register(
+        name="my_first_random_reg",
+        size=16,
+    )
+    circuit.populate_random_bits(bit_list=reg_one.to_list())
+
+    reg_two = circuit.add_c_register(
+        name="my_second_random_reg",
+        size=32,
+    )
+    circuit.populate_random_bits(bit_list=reg_two.to_list())
+
+    backend = QuantinuumBackend(
+        device_name="H1-1LE", api_handler=QuantinuumAPIOffline()
+    )
+    n_shots = 1000
+
+    compiled_circuit = backend.get_compiled_circuit(circuit)
+    result = backend.run_circuit(
+        circuit=compiled_circuit,
+        n_shots=n_shots,
+        seed=0,
+    )
+
+    for cbits in reg_one:
+        assert abs(result.get_counts(cbits=[cbits])[(0,)] - n_shots / 2) < 35
+
+    for cbits in reg_two:
+        assert abs(result.get_counts(cbits=[cbits])[(0,)] - n_shots / 2) < 35

pytket-mbqc-py/tests/test_qubit_manager.py

@@ -7,7 +7,12 @@
 def test_simple_measurement():
     qubit_mgr = QubitManager(n_physical_qubits=2)
 
-    qubit = qubit_mgr.get_qubit()
+    reg = qubit_mgr.add_c_register(
+        name="meas_reg",
+        size=1,
+    )
+
+    qubit = qubit_mgr.get_qubit(measure_bit=reg[0])
 
     assert qubit_mgr.available_qubit_list == [Qubit(1)]
     assert qubit_mgr.all_qubit_list == [Qubit(0), Qubit(1)]