Merge branch 'main' of https://github.com/Qiskit-Extensions/circuit-k…

…nitting-toolbox into LO-gate-cuts-optimizer

.github/workflows/citation.yml

@@ -63,7 +63,7 @@ jobs:
           fi
       - name: Upload PDF
         if: always()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: preview.pdf
           path: preview.pdf

.github/workflows/coverage.yml

@@ -23,7 +23,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install tox

.github/workflows/docs.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: actions/setup-python@v4
+      - uses: actions/setup-python@v5
         with:
           python-version: '3.9'
       - name: Install dependencies
@@ -39,12 +39,12 @@ jobs:
           tox -edocs
       - name: Upload docs artifact
         if: always()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: html_docs
           path: ./docs/_build/html
       - name: Deploy docs
-        if: ${{ github.ref == 'refs/heads/stable/0.4' }}
+        if: ${{ github.ref == 'refs/heads/stable/0.5' }}
         uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/lint.yml

@@ -19,7 +19,7 @@ jobs:
         with:
           fetch-depth: 0
       - name: Set up Python 3.9
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: '3.9'
       - name: Install tox

.github/workflows/test_development_versions.yml

@@ -23,7 +23,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies (development versions)
@@ -32,11 +32,12 @@ jobs:
           python -m pip install --upgrade pip tox
           python -m pip install toml typer
           python tools/extremal-python-dependencies.py add-dependency \
-              "qiskit-terra @ git+https://github.com/Qiskit/qiskit.git" \
+              "qiskit-terra @ git+https://github.com/Qiskit/qiskit.git@stable/0.46" \
               --inplace
           python tools/extremal-python-dependencies.py pin-dependencies \
-              "qiskit @ git+https://github.com/Qiskit/qiskit.git#subdirectory=qiskit_pkg" \
+              "qiskit @ git+https://github.com/Qiskit/qiskit.git@stable/0.46#subdirectory=qiskit_pkg" \
               "qiskit-ibm-runtime @ git+https://github.com/Qiskit/qiskit-ibm-runtime.git" \
+              "qiskit-algorithms @ git+https://github.com/qiskit-community/qiskit-algorithms.git" \
               --inplace
       - name: Modify tox.ini for more thorough check
         shell: bash

.github/workflows/test_latest_versions.yml

@@ -29,7 +29,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies

.github/workflows/test_minimum_versions.yml

@@ -21,7 +21,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies (minimum versions)

.mergify.yml

@@ -5,4 +5,4 @@ pull_request_rules:
     actions:
       backport:
         branches:
-          - stable/0.4
+          - stable/0.5

README.md

@@ -5,8 +5,8 @@
   [![Release](https://img.shields.io/pypi/v/circuit-knitting-toolbox.svg?label=Release)](https://github.com/Qiskit-Extensions/circuit-knitting-toolbox/releases)
   ![Platform](https://img.shields.io/badge/%F0%9F%92%BB%20Platform-Linux%20%7C%20macOS%20%7C%20Windows-informational)
   [![Python](https://img.shields.io/pypi/pyversions/circuit-knitting-toolbox?label=Python&logo=python)](https://www.python.org/)
-  [![Qiskit](https://img.shields.io/badge/Qiskit-%E2%89%A5%200.43.0-6133BD?logo=qiskit)](https://github.com/Qiskit/qiskit)
-  [![Qiskit Nature](https://img.shields.io/badge/Qiskit%20Nature-%E2%89%A5%200.6.0-6133BD?logo=qiskit)](https://github.com/Qiskit/qiskit-nature)
+  [![Qiskit](https://img.shields.io/badge/Qiskit-%E2%89%A5%200.44.1%2C%20%3C1.0-6133BD?logo=qiskit)](https://github.com/Qiskit/qiskit)
+  [![Qiskit Nature](https://img.shields.io/badge/Qiskit%20Nature-%E2%89%A5%200.6.0%2C%20%3C0.7-6133BD?logo=qiskit)](https://github.com/Qiskit/qiskit-nature)
 <br />
   [![Docs (stable)](https://img.shields.io/badge/%F0%9F%93%84%20Docs-stable-blue.svg)](https://qiskit-extensions.github.io/circuit-knitting-toolbox/)
   [![DOI](https://zenodo.org/badge/543181258.svg)](https://zenodo.org/badge/latestdoi/543181258)

circuit_knitting/cutting/cutqc/wire_cutting.py

@@ -483,7 +483,6 @@ def find_wire_cuts(
         subcircuits: Sequence[Any] = cut_solution["subcircuits"]
         num_cuts: int = cut_solution["num_cuts"]
         _print_cutter_result(
-            num_subcircuit=len(subcircuits),
             num_cuts=num_cuts,
             subcircuits=subcircuits,
             counter=counter,
@@ -558,7 +557,6 @@ def cut_circuit_wire(
     if verbose:
         print("-" * 20)
         _print_cutter_result(
-            num_subcircuit=len(cut_solution["subcircuits"]),
             num_cuts=cut_solution["num_cuts"],
             subcircuits=cut_solution["subcircuits"],
             counter=cut_solution["counter"],
@@ -569,7 +567,6 @@ def cut_circuit_wire(
 
 
 def _print_cutter_result(
-    num_subcircuit: int,
     num_cuts: int,
     subcircuits: Sequence[QuantumCircuit],
     counter: dict[int, dict[str, int]],
@@ -579,7 +576,6 @@ def _print_cutter_result(
     Pretty print the results.
 
     Args:
-        num_subciruit: The number of subcircuits
         num_cuts: The number of cuts
         subcircuits: The list of subcircuits
         counter: The dictionary containing all meta information regarding
@@ -589,7 +585,8 @@ def _print_cutter_result(
     Returns:
         None
     """
-    for subcircuit_idx in range(num_subcircuit):
+    print(f"num_cuts = {num_cuts}")
+    for subcircuit_idx, subcircuit in enumerate(subcircuits):
         print("subcircuit %d" % subcircuit_idx)
         print(
             "\u03C1 qubits = %d, O qubits = %d, width = %d, effective = %d, depth = %d, size = %d"
@@ -602,7 +599,7 @@ def _print_cutter_result(
                 counter[subcircuit_idx]["size"],
             )
         )
-        print(subcircuits[subcircuit_idx])
+        print(subcircuit)
     print("Estimated cost = %.3e" % classical_cost, flush=True)
 
 
@@ -621,7 +618,7 @@ def _cuts_parser(
         that are affected by these cuts
     """
     dag = circuit_to_dag(circ)
-    positions = []
+    positions: list[tuple[Qubit, int]] = []
     for position in cuts:
         if len(position) != 2:
             raise ValueError(

circuit_knitting/cutting/cutting_evaluation.py

@@ -132,15 +132,15 @@ def execute_experiments(
         assert isinstance(samplers, dict)
         samplers_dict = samplers
 
-    # Make sure the first two cregs in each circuit are for QPD and observable measurements
+    # Make sure the first two cregs in each circuit are for observable and QPD measurements, respectively.
     # Run a job for each partition and collect results
     results = {}
     for label in subexperiments_dict.keys():
         for circ in subexperiments_dict[label]:
             if (
                 len(circ.cregs) != 2
-                or circ.cregs[1].name != "observable_measurements"
-                or circ.cregs[0].name != "qpd_measurements"
+                or circ.cregs[0].name != "observable_measurements"
+                or circ.cregs[1].name != "qpd_measurements"
                 or sum([reg.size for reg in circ.cregs]) != circ.num_clbits
             ):
                 # If the classical bits/registers are in any other format than expected, the user must have
@@ -150,10 +150,6 @@ def execute_experiments(
                 )
         results[label] = samplers_dict[label].run(subexperiments_dict[label]).result()
 
-    for label, result in results.items():
-        for i, metadata in enumerate(result.metadata):
-            metadata["num_qpd_bits"] = len(subexperiments_dict[label][i].cregs[0])
-
     # If the input was a circuit, the output results should be a single SamplerResult instance
     results_out = results
     if isinstance(circuits, QuantumCircuit):

circuit_knitting/cutting/cutting_experiments.py

@@ -19,8 +19,11 @@
 import numpy as np
 from qiskit.circuit import QuantumCircuit, ClassicalRegister
 from qiskit.quantum_info import PauliList
+from qiskit.transpiler import PassManager
+from qiskit.transpiler.passes import RemoveResetInZeroState, DAGFixedPoint
 
 from ..utils.iteration import strict_zip
+from ..utils.transpiler_passes import RemoveFinalReset, ConsolidateResets
 from ..utils.observable_grouping import ObservableCollection, CommutingObservableGroup
 from .qpd import (
     WeightType,
@@ -54,10 +57,16 @@ def generate_cutting_experiments(
 
     In both cases, the subexperiment lists are ordered as follows:
 
-        :math:`[sample_{0}observable_{0}, \ldots, sample_{0}observable_{N}, sample_{1}observable_{0}, \ldots, sample_{M}observable_{N}]`
+        :math:`[sample_{0}observable_{0}, \ldots, sample_{0}observable_{N-1}, sample_{1}observable_{0}, \ldots, sample_{M-1}observable_{N-1}]`
 
     The coefficients will always be returned as a 1D array -- one coefficient for each unique sample.
 
+    Note that this function also runs some transpiler passes on each generated
+    circuit, namely :class:`~qiskit.transpiler.passes.RemoveResetInZeroState`,
+    :class:`.RemoveFinalReset`, and :class:`.ConsolidateResets`, in order to
+    remove unnecessary :class:`~qiskit.circuit.library.Reset`\ s from the
+    circuit that are added by the subexperiment decompositions for cut wires.
+
     Args:
         circuits: The circuit(s) to partition and separate
         observables: The observable(s) to evaluate for each unique sample
@@ -148,12 +157,32 @@ def generate_cutting_experiments(
             subcircuit = subcircuit_dict[label]
             if is_separated:
                 map_ids_tmp = tuple(map_ids[j] for j in subcirc_map_ids[label])
-            decomp_qc = decompose_qpd_instructions(
-                subcircuit, subcirc_qpd_gate_ids[label], map_ids_tmp
-            )
             for j, cog in enumerate(so.groups):
-                meas_qc = _append_measurement_circuit(decomp_qc, cog)
-                subexperiments_dict[label].append(meas_qc)
+                new_qc = _append_measurement_register(subcircuit, cog)
+                decompose_qpd_instructions(
+                    new_qc, subcirc_qpd_gate_ids[label], map_ids_tmp, inplace=True
+                )
+                _append_measurement_circuit(new_qc, cog, inplace=True)
+                subexperiments_dict[label].append(new_qc)
+
+    # Remove initial and final resets from the subexperiments.  This will
+    # enable the `Move` operation to work on backends that don't support
+    # `Reset`, as long as qubits are not re-used.  See
+    # https://github.com/Qiskit-Extensions/circuit-knitting-toolbox/issues/452.
+    # While we are at it, we also consolidate each run of multiple resets
+    # (which can arise when re-using qubits) into a single reset.
+    pass_manager = PassManager()
+    pass_manager.append(
+        [
+            RemoveResetInZeroState(),
+            RemoveFinalReset(),
+            ConsolidateResets(),
+            DAGFixedPoint(),
+        ],
+        do_while=lambda property_set: not property_set["dag_fixed_point"],
+    )
+    for label, subexperiments in subexperiments_dict.items():
+        subexperiments_dict[label] = pass_manager.run(subexperiments)
 
     # If the input was a single quantum circuit, return the subexperiments as a list
     subexperiments_out: list[QuantumCircuit] | dict[
@@ -231,6 +260,37 @@ def _get_bases(circuit: QuantumCircuit) -> tuple[list[QPDBasis], list[list[int]]
     return bases, qpd_gate_ids
 
 
+def _append_measurement_register(
+    qc: QuantumCircuit,
+    cog: CommutingObservableGroup,
+    /,
+    *,
+    inplace: bool = False,
+):
+    """Append a new classical register for the given ``CommutingObservableGroup``.
+
+    The new register will be named ``"observable_measurements"`` and will be
+    the final register in the returned circuit, i.e. ``retval.cregs[-1]``.
+
+    Args:
+        qc: The quantum circuit
+        cog: The commuting observable set for which to construct measurements
+        inplace: Whether to operate on the circuit in place (default: ``False``)
+
+    Returns:
+        The modified circuit
+    """
+    if not inplace:
+        qc = qc.copy()
+
+    pauli_indices = _get_pauli_indices(cog)
+
+    obs_creg = ClassicalRegister(len(pauli_indices), name="observable_measurements")
+    qc.add_register(obs_creg)
+
+    return qc
+
+
 def _append_measurement_circuit(
     qc: QuantumCircuit,
     cog: CommutingObservableGroup,
@@ -239,15 +299,15 @@ def _append_measurement_circuit(
     qubit_locations: Sequence[int] | None = None,
     inplace: bool = False,
 ) -> QuantumCircuit:
-    """Append a new classical register and measurement instructions for the given ``CommutingObservableGroup``.
+    """Append measurement instructions for the given ``CommutingObservableGroup``.
 
-    The new register will be named ``"observable_measurements"`` and will be
-    the final register in the returned circuit, i.e. ``retval.cregs[-1]``.
+    The measurement results will be placed in a register with the name
+    ``"observable_measurements"``.  Such a register can be created by calling
+    :func:`_append_measurement_register` before calling the current function.
 
     Args:
         qc: The quantum circuit
-        cog: The commuting observable set for
-            which to construct measurements
+        cog: The commuting observable set for which to construct measurements
         qubit_locations: A ``Sequence`` whose length is the number of qubits
             in the observables, where each element holds that qubit's corresponding
             index in the circuit.  By default, the circuit and observables are assumed
@@ -273,24 +333,56 @@ def _append_measurement_circuit(
                 f"qubit_locations has {len(qubit_locations)} element(s) but the "
                 f"observable(s) have {cog.general_observable.num_qubits} qubit(s)."
             )
+
+    # Find observable_measurements register
+    for reg in qc.cregs:
+        if reg.name == "observable_measurements":
+            obs_creg = reg
+            break
+    else:
+        raise ValueError('Cannot locate "observable_measurements" register')
+
+    pauli_indices = _get_pauli_indices(cog)
+
+    if obs_creg.size != len(pauli_indices):
+        raise ValueError(
+            '"observable_measurements" register is the wrong size '
+            "for the given commuting observable group "
+            f"({obs_creg.size} != {len(pauli_indices)})"
+        )
+
     if not inplace:
         qc = qc.copy()
 
     # Append the appropriate measurements to qc
-    obs_creg = ClassicalRegister(len(cog.pauli_indices), name="observable_measurements")
-    qc.add_register(obs_creg)
+    #
     # Implement the necessary basis rotations and measurements, as
     # in BackendEstimator._measurement_circuit().
     genobs_x = cog.general_observable.x
     genobs_z = cog.general_observable.z
-    for clbit, subqubit in enumerate(cog.pauli_indices):
+    for clbit, subqubit in enumerate(pauli_indices):
         # subqubit is the index of the qubit in the subsystem.
         # actual_qubit is its index in the system of interest (if different).
         actual_qubit = qubit_locations[subqubit]
         if genobs_x[subqubit]:
             if genobs_z[subqubit]:
-                qc.sdg(actual_qubit)
-            qc.h(actual_qubit)
+                # Rotate Y basis to Z basis
+                qc.sx(actual_qubit)
+            else:
+                # Rotate X basis to Z basis
+                qc.h(actual_qubit)
+        # Measure in Z basis
         qc.measure(actual_qubit, obs_creg[clbit])
 
     return qc
+
+
+def _get_pauli_indices(cog: CommutingObservableGroup) -> list[int]:
+    """Return the indices to qubits to be measured."""
+    # If the circuit has no measurements, the Sampler will fail.  So, we
+    # measure one qubit as a temporary workaround to
+    # https://github.com/Qiskit-Extensions/circuit-knitting-toolbox/issues/422
+    pauli_indices = cog.pauli_indices
+    if not pauli_indices:
+        pauli_indices = [0]
+    return pauli_indices