Merge pull request #30 from CQCL/main

_metadata.py

@@ -1,2 +1,2 @@
-__extension_version__ = "0.2.1"
+__extension_version__ = "0.3.0"
 __extension_name__ = "pytket-cutensornet"

docs/changelog.rst

@@ -1,6 +1,13 @@
 Changelog
 ~~~~~~~~~
 
+0.3.0 (September 2023)
+----------------------
+
+* Added MPS sampling feature.
+* Refactored MPS module for better maintainability and extendability.
+* ``Tensor`` class removed from the API since it is no longer necessary.
+
 0.2.1 (August 2023)
 -------------------
 
@@ -16,4 +23,4 @@ Changelog
 0.1.0 (June 2023)
 -----------------
 
-* Initial implementation of the converter and backend modules for use on a single GPU.
+* Initial implementation of the converter and backend modules for use on a single GPU.

pytket/extensions/cutensornet/mps/mps.py

@@ -30,8 +30,8 @@
 except ImportError:
     warnings.warn("local settings failed to import cutensornet", ImportWarning)
 
-from pytket.circuit import Command, Op, OpType, Qubit  # type: ignore
-from pytket.pauli import Pauli, QubitPauliString  # type: ignore
+from pytket.circuit import Command, Op, OpType, Qubit
+from pytket.pauli import Pauli, QubitPauliString
 
 # An alias so that `intptr_t` from CuQuantum's API (which is not available in
 # base python) has some meaningful type name.

pytket/extensions/cutensornet/mps/mps_gate.py

@@ -26,7 +26,7 @@
 except ImportError:
     warnings.warn("local settings failed to import cutensornet", ImportWarning)
 
-from pytket.circuit import Op  # type: ignore
+from pytket.circuit import Op
 from .mps import MPS
 
 

pytket/extensions/cutensornet/mps/mps_mpo.py

@@ -28,7 +28,7 @@
 except ImportError:
     warnings.warn("local settings failed to import cutensornet", ImportWarning)
 
-from pytket.circuit import Op, Qubit  # type: ignore
+from pytket.circuit import Op, Qubit
 from .mps import (
     CuTensorNetHandle,
     DirectionMPS,

pytket/extensions/cutensornet/mps/simulation.py

@@ -4,11 +4,11 @@
 from collections import defaultdict  # type: ignore
 import numpy as np  # type: ignore
 
-from pytket.circuit import Circuit, Command, Qubit  # type: ignore
-from pytket.transform import Transform  # type: ignore
-from pytket.architecture import Architecture  # type: ignore
-from pytket.passes import DefaultMappingPass  # type: ignore
-from pytket.predicates import CompilationUnit  # type: ignore
+from pytket.circuit import Circuit, Command, Qubit
+from pytket.transform import Transform
+from pytket.architecture import Architecture
+from pytket.passes import DefaultMappingPass
+from pytket.predicates import CompilationUnit
 
 from .mps import CuTensorNetHandle, MPS
 from .mps_gate import MPSxGate
@@ -120,7 +120,11 @@ def prepare_circuit(circuit: Circuit) -> tuple[Circuit, dict[Qubit, Qubit]]:
     prep_circ = cu.circuit
     Transform.DecomposeBRIDGE().apply(prep_circ)
 
-    qubit_map = {arch_q: orig_q for orig_q, arch_q in cu.final_map.items()}
+    qubit_map: dict[Qubit, Qubit] = {}
+    for orig_q, arch_q in cu.final_map.items():
+        assert isinstance(orig_q, Qubit)
+        assert isinstance(arch_q, Qubit)
+        qubit_map[arch_q] = orig_q
 
     return (prep_circ, qubit_map)
 
@@ -190,6 +194,7 @@ def _get_sorted_gates(circuit: Circuit) -> list[Command]:
                 "nearest neighbour qubits. Consider using prepare_circuit().",
             )
         elif left_distance is None:
+            assert right_distance is not None
             current_qubit = circuit.qubits[q_index + right_distance]
         elif right_distance is None:
             current_qubit = circuit.qubits[q_index - left_distance]

pytket/extensions/cutensornet/tensor_network_convert.py

@@ -152,7 +152,7 @@ def _get_gate_tensors(self, adj: bool = False) -> DefaultDict[Any, List[Any]]:
                         self._logger.debug(f"Adding unitary: \n {com.op.get_unitary()}")
                     # Add a unitary for a gate pointing "upwards" (e.g. CX[1, 0])
                     if com.op.n_qubits > 1:
-                        com_qix = [self._circuit.qubits.index(qb) for qb in com.args]
+                        com_qix = [self._circuit.qubits.index(qb) for qb in com.qubits]
                         self._logger.debug(f"command qubit indices: {com_qix}")
                         com_qix_compressed = [i for i, _ in enumerate(com_qix)]
                         self._logger.debug(

tests/conftest.py

@@ -1,8 +1,8 @@
 import pytest
 import numpy as np
 from scipy.stats import unitary_group  # type: ignore
-from pytket.circuit import Circuit, OpType, Unitary2qBox  # type: ignore
-from pytket.passes import DecomposeBoxes  # type: ignore
+from pytket.circuit import Circuit, OpType, Unitary2qBox
+from pytket.passes import DecomposeBoxes
 
 
 def random_line_circuit(n_qubits: int, layers: int) -> Circuit:
@@ -21,7 +21,8 @@ def random_line_circuit(n_qubits: int, layers: int) -> Circuit:
         ]
         # Direction of each CX gate is random
         for pair in qubit_pairs:
-            np.random.shuffle(pair)
+            if np.random.rand() > 0.5:
+                pair = [pair[1], pair[0]]
 
         for pair in qubit_pairs:
             c.CX(pair[0], pair[1])

tests/test_mps.py

@@ -327,13 +327,13 @@ def test_circ_approx_explicit(circuit: Circuit) -> None:
         # Fixed virtual bond dimension
         # Check for MPSxGate
         mps_gate = simulate(libhandle, circuit, ContractionAlg.MPSxGate, chi=8)
-        assert np.isclose(mps_gate.fidelity, 0.05, atol=1e-2)
+        assert np.isclose(mps_gate.fidelity, 0.03, atol=1e-2)
         assert mps_gate.is_valid()
         assert np.isclose(mps_gate.vdot(mps_gate), 1.0, atol=mps_gate._atol)
 
         # Check for MPSxMPO
         mps_mpo = simulate(libhandle, circuit, ContractionAlg.MPSxMPO, chi=8)
-        assert np.isclose(mps_mpo.fidelity, 0.09, atol=1e-2)
+        assert np.isclose(mps_mpo.fidelity, 0.06, atol=1e-2)
         assert mps_mpo.is_valid()
         assert np.isclose(mps_mpo.vdot(mps_mpo), 1.0, atol=mps_mpo._atol)
 

tests/test_tensor_network_convert.py

@@ -79,8 +79,8 @@ def test_toffoli_box_with_implicit_swaps() -> None:
     ket_circ = Circuit(3)
 
     # Create the circuit
-    ket_circ.add_toffolibox(ToffoliBox(perm), [Qubit(0), Qubit(1)])
-    ket_circ.add_toffolibox(ToffoliBox(perm), [Qubit(1), Qubit(2)])
+    ket_circ.add_toffolibox(ToffoliBox(perm), [Qubit(0), Qubit(1)])  # type: ignore
+    ket_circ.add_toffolibox(ToffoliBox(perm), [Qubit(1), Qubit(2)])  # type: ignore
 
     DecomposeBoxes().apply(ket_circ)
     CnXPairwiseDecomposition().apply(ket_circ)
@@ -116,7 +116,7 @@ def to_bool_tuple(n_qubits: int, x: int) -> tuple:
         perm[to_bool_tuple(n_qubits, orig)] = to_bool_tuple(n_qubits, dest)
 
     # Create a circuit implementing the permutation above
-    ket_circ = ToffoliBox(perm).get_circuit()
+    ket_circ = ToffoliBox(perm).get_circuit()  # type: ignore
 
     DecomposeBoxes().apply(ket_circ)
     CnXPairwiseDecomposition().apply(ket_circ)