Merge branch 'main' into update-ci

requirements.txt

@@ -1,11 +1,12 @@
-qiskit>=0.43,<1
+qiskit
 qiskit-aer>=0.11.0
 qiskit_ibm_provider>=0.5.0
 pybind11<=2.9.1
 PyMatching>=0.6.0,!=2.0.0
 rustworkx>=0.12.0
 networkx>=2.6.3
 sympy>=1.9
+testtools
 numpy>=1.21.0
 ipython
 ipywidgets>=8.0.5

src/qiskit_qec/__init__.py

@@ -24,6 +24,7 @@
     linear,
     operators,
     structures,
+    test,
     utils,
 )
 

src/qiskit_qec/circuits/repetition_code.py

@@ -23,11 +23,6 @@
 import networkx as nx
 
 from qiskit import ClassicalRegister, QuantumCircuit, QuantumRegister, transpile
-from qiskit.circuit.library import XGate, RZGate
-from qiskit.transpiler import PassManager, InstructionDurations
-from qiskit_ibm_provider.transpiler.passes.scheduling import DynamicCircuitInstructionDurations
-from qiskit_ibm_provider.transpiler.passes.scheduling import PadDynamicalDecoupling
-from qiskit_ibm_provider.transpiler.passes.scheduling import ALAPScheduleAnalysis
 
 from qiskit_qec.circuits.code_circuit import CodeCircuit
 from qiskit_qec.utils import DecodingGraphEdge, DecodingGraphNode
@@ -979,6 +974,7 @@ def _process_string(self, string):
                 q_l = self.num_qubits[1] - 1 - j
                 qubit_l = self.links[q_l][1]
                 # the first results are themselves the changes
+                change = None
                 if t == 0:
                     change = syndrome_list[-1][j] != "0"
                 # if the link was involved in a just finished 202...
@@ -1222,19 +1218,16 @@ def is_cluster_neutral(self, nodes: dict):
             self._linear,
         )
 
-    def transpile(self, backend, echo=("X", "X"), echo_num=(2, 0)):
+    def transpile(self, backend, scheduling_method="alap"):
         """
         Args:
             backend (qiskit.providers.ibmq.IBMQBackend): Backend to transpile and schedule the
             circuits for. The numbering of the qubits in this backend should correspond to
             the numbering used in `self.links`.
-            echo (tuple): List of gate sequences (expressed as strings) to be used on code qubits and
-            link qubits, respectively. Valid strings are `'X'` and `'XZX'`.
-            echo_num (tuple): Number of times to repeat the sequences for code qubits and
-            link qubits, respectively.
+            scheduling_method (str): Name of scheduling pass. Arguemnt passed to `qiskit.transpile`.
         Returns:
-            transpiled_circuit: As `self.circuit`, but with the circuits scheduled, transpiled and
-            with dynamical decoupling added.
+            transpiled_circuit: As `self.circuit`, but with the circuits scheduled and remapped
+            to the device connectivity.
         """
 
         bases = list(self.circuit.keys())
@@ -1248,51 +1241,9 @@ def transpile(self, backend, echo=("X", "X"), echo_num=(2, 0)):
             ]
 
         # transpile to backend
-        circuits = transpile(circuits, backend, initial_layout=initial_layout)
-
-        # then dynamical decoupling if needed
-        if any(echo_num):
-            if self.run_202:
-                durations = DynamicCircuitInstructionDurations().from_backend(backend)
-            else:
-                durations = InstructionDurations().from_backend(backend)
-
-            # set up the dd sequences
-            dd_sequences = []
-            spacings = []
-            for j in range(2):
-                if echo[j] == "X":
-                    dd_sequences.append([XGate()] * echo_num[j])
-                    spacings.append(None)
-                elif echo[j] == "XZX":
-                    dd_sequences.append([XGate(), RZGate(np.pi), XGate()] * echo_num[j])
-                    d = 1.0 / (2 * echo_num[j] - 1 + 1)
-                    spacing = [d / 2] + ([0, d, d] * echo_num[j])[:-1] + [d / 2]
-                    for _ in range(2):
-                        spacing[0] += 1 - sum(spacing)
-                    spacings.append(spacing)
-                else:
-                    dd_sequences.append(None)
-                    spacings.append(None)
-
-            # add in the dd sequences
-            for j, dd_sequence in enumerate(dd_sequences):
-                if dd_sequence:
-                    if echo_num[j]:
-                        qubits = self.qubits[j]
-                    else:
-                        qubits = None
-                    pm = PassManager(
-                        [
-                            ALAPScheduleAnalysis(durations),
-                            PadDynamicalDecoupling(
-                                durations, dd_sequence, qubits=qubits, spacings=spacings[j]
-                            ),
-                        ]
-                    )
-                    circuits = pm.run(circuits)
-            if not isinstance(circuits, list):
-                circuits = [circuits]
+        circuits = transpile(
+            circuits, backend, initial_layout=initial_layout, scheduling_method=scheduling_method
+        )
 
         return {basis: circuits[j] for j, basis in enumerate(bases)}
 

src/qiskit_qec/test/__init__.py

@@ -0,0 +1,27 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2017, 2018.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Functionality and helpers for testing Qiskit."""
+
+import warnings
+from .base import QiskitTestCase
+from .decorators import requires_aer_provider, online_test, slow_test
+from .reference_circuits import ReferenceCircuits
+from .utils import Path
+
+warnings.warn(
+    "The `qiskit.test` module is deprecated since Qiskit 0.46, and will be removed in Qiskit 1.0."
+    " This module was internal to Qiskit's test suite; if you absolutely require any of its"
+    " functionality, consider vendoring the code into your own project.",
+    DeprecationWarning,
+    stacklevel=2,
+)

src/qiskit_qec/test/_canonical.py

@@ -0,0 +1,125 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2022.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Utility methods for canonicalising various Qiskit objects, to help with testing."""
+
+import threading
+
+from qiskit.circuit import (
+    BreakLoopOp,
+    CircuitInstruction,
+    ContinueLoopOp,
+    ControlFlowOp,
+    ForLoopOp,
+    Parameter,
+    QuantumCircuit,
+)
+
+
+class _CanonicalParametersIterator:
+    """An object that, when iterated through, will produce the same sequence of parameters as every
+    other instance of this iterator."""
+
+    __parameters = []
+    __mutex = threading.Lock()
+
+    def __init__(self):
+        self._counter = 0
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        with self.__mutex:
+            if len(self.__parameters) >= self._counter:
+                param = Parameter(f"_canonicalization_loop_{self._counter}")
+                self.__parameters.append(param)
+            out = self.__parameters[self._counter]
+            self._counter += 1
+            return out
+
+
+def canonicalize_control_flow(circuit: QuantumCircuit) -> QuantumCircuit:
+    """Canonicalize all control-flow operations in a circuit.
+
+    This is not an efficient operation, and does not affect any properties of the circuit.  Its
+    intent is to normalise parts of circuits that have a non-deterministic construction.  These are
+    the ordering of bit arguments in control-flow blocks output by the builder interface, and
+    automatically generated ``for``-loop variables.
+
+    The canonical form sorts the bits in the arguments of these operations so that they always
+    appear in the order they were originally added to the outer-most circuit.  For-loop variables
+    are re-bound into new, cached auto-generated ones."""
+    params = iter(_CanonicalParametersIterator())
+    base_bit_order = {bit: i for i, bit in enumerate(circuit.qubits)}
+    base_bit_order.update((bit, i) for i, bit in enumerate(circuit.clbits))
+
+    def worker(circuit, bit_map=None):
+        if bit_map is None:
+            bit_map = {bit: bit for bits in (circuit.qubits, circuit.clbits) for bit in bits}
+
+        def bit_key(bit):
+            return base_bit_order[bit_map[bit]]
+
+        # This isn't quite QuantumCircuit.copy_empty_like because of the bit reordering.
+        out = QuantumCircuit(
+            sorted(circuit.qubits, key=bit_key),
+            sorted(circuit.clbits, key=bit_key),
+            *circuit.qregs,
+            *circuit.cregs,
+            name=circuit.name,
+            global_phase=circuit.global_phase,
+            metadata=circuit.metadata,
+        )
+        for instruction in circuit.data:
+            new_instruction = instruction
+            # Control-flow operations associated bits in the instruction arguments with bits in the
+            # circuit blocks just by sequencing.  All blocks must have the same width.
+            if isinstance(new_instruction.operation, ControlFlowOp):
+                op = new_instruction.operation
+                first_block = op.blocks[0]
+                inner_bit_map = dict(
+                    zip(first_block.qubits, (bit_map[bit] for bit in new_instruction.qubits))
+                )
+                inner_bit_map.update(
+                    zip(first_block.clbits, (bit_map[bit] for bit in new_instruction.clbits))
+                )
+                new_instruction = CircuitInstruction(
+                    operation=op.replace_blocks(
+                        [worker(block, inner_bit_map) for block in op.blocks]
+                    ),
+                    qubits=sorted(new_instruction.qubits, key=bit_key),
+                    clbits=sorted(new_instruction.clbits, key=bit_key),
+                )
+            elif isinstance(new_instruction.operation, (BreakLoopOp, ContinueLoopOp)):
+                new_instruction = new_instruction.replace(
+                    qubits=sorted(new_instruction.qubits, key=bit_key),
+                    clbits=sorted(new_instruction.clbits, key=bit_key),
+                )
+            # For for loops specifically, the control-flow builders generate a loop parameter if one
+            # is needed but not explicitly supplied.  We want the parameters to compare equal, so we
+            # replace them with those from a shared list.
+            if isinstance(new_instruction.operation, ForLoopOp):
+                old_op = new_instruction.operation
+                indexset, loop_param, body = old_op.params
+                if loop_param is not None:
+                    new_loop_param = next(params)
+                    new_op = ForLoopOp(
+                        indexset,
+                        new_loop_param,
+                        body.assign_parameters({loop_param: new_loop_param}),
+                    )
+                    new_instruction = new_instruction.replace(operation=new_op)
+            out._append(new_instruction)
+        return out
+
+    return worker(circuit)