Merge branch 'main' into fix/dd-classical-control

Author: mhucka

.github/workflows/ci.yml

@@ -287,7 +287,7 @@ jobs:
       - name: Coverage check
         run: check/pytest-and-incremental-coverage -n logical
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@671740ac38dd9b0130fbe1cec585b89eea48d3de # v5.5.2
+        uses: codecov/codecov-action@57e3a136b779b570ffcdbf80b3bdc90e7fab3de2 # v6.0.0
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
   windows:
@@ -419,7 +419,7 @@ jobs:
       - name: Check out source repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Node environment
-        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
           node-version: '22.16.0'
       - name: Install node dependencies
@@ -434,7 +434,7 @@ jobs:
       - name: Check out source repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Node environment
-        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
           node-version: '22.16.0'
       - name: Install node dependencies
@@ -449,7 +449,7 @@ jobs:
       - name: Check out source repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Node environment
-        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
           node-version: '22.16.0'
       - name: Install node dependencies
@@ -466,7 +466,7 @@ jobs:
       - name: Check out source repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Node environment
-        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
           node-version: '22.16.0'
       - name: Install node dependencies

.github/workflows/scorecard-scanner.yaml

@@ -61,13 +61,23 @@ jobs:
         uses: ossf/scorecard-action@4eaacf0543bb3f2c246792bd56e8cdeffafb205a # v2.4.3
         with:
           # Save the results
-          results_file: scorecard-results.sarif
+          results_file: raw-scorecard-results.sarif
           results_format: sarif
           # See https://github.com/ossf/scorecard-action#publishing-results.
           publish_results: true
 
+      - name: Filter results
+        uses: advanced-security/filter-sarif@2da736ff05ef065cb2894ac6892e47b5eac2c3c0 # v1.1
+        with:
+          # The cifuzz action version cannot be pinned to a hash. Filter out those results to avoid
+          # repeated warnings that we can't do anything about.
+          patterns: |
+            -.github/workflows/cifuzz.yml:actions/unpinned-tag
+          input: raw-scorecard-results.sarif
+          output: scorecard-results.sarif
+
       - name: Upload results to code-scanning dashboard
         # yamllint disable rule:line-length
-        uses: github/codeql-action/upload-sarif@5d4e8d1aca955e8d8589aabd499c5cae939e33c7 # v4.31.9
+        uses: github/codeql-action/upload-sarif@c10b8064de6f491fea524254123dbe5e09572f13 # v4.35.1
         with:
           sarif_file: scorecard-results.sarif

cirq-core/cirq/contrib/acquaintance/gates.py

@@ -285,11 +285,14 @@ def _decompose_(self, qubits: Sequence[cirq.Qid]) -> Iterator[cirq.OP_TREE]:
             parts.append(list(qubits[n_qubits : n_qubits + part_len]))
             n_qubits += part_len
         n_parts = len(parts)
-        op_sort_key = (
-            None
-            if self.acquaintance_size is None
-            else (lambda op: min(qubit_to_position[q] for q in op.qubits) % self.acquaintance_size)
-        )
+
+        # acquaintance_size for the modulo operation in op_sort_key.
+        # Produce constant key (no sorting) when None or 0.
+        mod_acquaintance_size: int = self.acquaintance_size or 1
+
+        def op_sort_key(op: cirq.Operation) -> int:
+            return min(qubit_to_position[q] for q in op.qubits) % mod_acquaintance_size
+
         layers = new_layers()
         for layer_num in range(n_parts):
             layers = new_layers(prior_interstitial=layers.posterior_interstitial)
@@ -306,11 +309,11 @@ def _decompose_(self, qubits: Sequence[cirq.Qid]) -> Iterator[cirq.OP_TREE]:
                 parts_qubits = list(left_part + right_part)
                 parts[i] = parts_qubits[: len(right_part)]
                 parts[i + 1] = parts_qubits[len(right_part) :]
-            if op_sort_key is not None:
+            if self.acquaintance_size is not None:
                 layers.prior_interstitial.sort(key=op_sort_key)
             for l in ('prior_interstitial', 'pre', 'intra', 'post'):
                 yield getattr(layers, l)
-        if op_sort_key is not None:
+        if self.acquaintance_size is not None:
             layers.posterior_interstitial.sort(key=op_sort_key)
         yield layers.posterior_interstitial
 

cirq-core/cirq/contrib/quantikz/circuit_to_latex_quantikz.py

@@ -412,8 +412,8 @@ def _get_gate_name(self, gate: ops.Gate) -> str:
                     return self._format_exponent_for_display(mapped_base)
 
                 if (
-                    hasattr(gate, "exponent")
-                    and not (isinstance(gate.exponent, float) and math.isclose(gate.exponent, 1.0))
+                    (gate_exponent := getattr(gate, "exponent", None)) is not None
+                    and not (isinstance(gate_exponent, float) and math.isclose(gate_exponent, 1.0))
                     and isinstance(gate, tuple(_EXPONENT_GATE_MAP.keys()))
                 ):
                     has_exp_in_cand = ("^" in name_cand) or ("**" in name_cand)
@@ -425,7 +425,7 @@ def _get_gate_name(self, gate: ops.Gate) -> str:
                         if needs_recon:
                             name_cand = (
                                 f"{recon_base}^"
-                                f"{{{self._format_exponent_for_display(gate.exponent)}}}"
+                                f"{{{self._format_exponent_for_display(gate_exponent)}}}"
                             )
 
                 fmt_name = self._escape_string(name_cand)

cirq-core/cirq/contrib/quimb/state_vector.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import warnings
 from collections.abc import Sequence
 from typing import cast, TYPE_CHECKING
 
@@ -15,21 +14,6 @@
     import numpy as np
 
 
-def _get_quimb_version():
-    """Returns the quimb version and parsed (major,minor) numbers if possible.
-    Returns:
-        a tuple of ((major, minor), version string)
-    """
-    version = quimb.__version__
-    try:
-        return tuple(int(x) for x in version.split('.')), version
-    except:  # pragma: no cover
-        return (0, 0), version
-
-
-QUIMB_VERSION = _get_quimb_version()
-
-
 def circuit_to_tensors(
     circuit: cirq.Circuit, qubits: Sequence[cirq.Qid] | None = None, initial_state: int | None = 0
 ) -> tuple[list[qtn.Tensor], dict[cirq.Qid, int], None]:
@@ -163,15 +147,7 @@ def tensor_expectation_value(
         for q in qubits
     ]
     tn = qtn.TensorNetwork(tensors + end_bras)
-    if QUIMB_VERSION[0] < (1, 3):
-        warnings.warn(  # pragma: no cover
-            f'quimb version {QUIMB_VERSION[1]} detected. Please use '
-            f'quimb>=1.3 for optimal performance in '
-            '`tensor_expectation_value`. '
-            'See https://github.com/quantumlib/Cirq/issues/3263'
-        )
-    else:
-        tn.rank_simplify(inplace=True)
+    tn.rank_simplify(inplace=True)
     path_info = tn.contract(get='path-info')
     ram_gb = path_info.largest_intermediate * 128 / 8 / 1024 / 1024 / 1024
     if ram_gb > max_ram_gb:

cirq-core/cirq/contrib/requirements.txt

@@ -4,5 +4,5 @@ ply>=3.6
 pylatex~=1.4
 
 # quimb
-quimb>=1.8
+quimb~=1.8
 opt_einsum

cirq-core/cirq/qis/measures.py

@@ -242,11 +242,10 @@ def _fidelity_state_vectors_or_density_matrices(state1: np.ndarray, state2: np.n
         # state1 is a density matrix and state2 is a state vector
         return np.real(np.conjugate(state2) @ state1 @ state2)
     elif state1.ndim == 2 and state2.ndim == 2:
-        # Both density matrices
-        state1_sqrt = _sqrt_positive_semidefinite_matrix(state1)
-        eigs = linalg.eigvalsh(state1_sqrt @ state2 @ state1_sqrt)
-        trace = np.sum(np.sqrt(np.abs(eigs)))
-        return trace**2
+        # Both density matrices: use SVD-based fidelity for numerical stability
+        rho1_sqrt = linalg.sqrtm(state1)
+        rho2_sqrt = linalg.sqrtm(state2)
+        return (np.sum(linalg.svdvals(rho1_sqrt @ rho2_sqrt))) ** 2
     # matrix is reshaped before this point
     raise ValueError(  # pragma: no cover
         'The given arrays must be one- or two-dimensional. '

cirq-core/cirq/qis/measures_test.py

@@ -20,6 +20,8 @@
 import pytest
 
 import cirq
+import cirq.qis.measures as measures
+from cirq import partial_trace
 
 N = 15
 VEC1 = cirq.testing.random_superposition(N)
@@ -187,6 +189,30 @@ def test_fidelity_bad_shape() -> None:
         _ = cirq.fidelity(np.array([[[1.0]]]), np.array([[[1.0]]]), qid_shape=(1,))
 
 
+def test_fidelity_numerical_stability_high_dim():
+    init_qubits = 10
+    final_qubits = init_qubits - 1
+    rng = np.random.RandomState(42)
+    psi = rng.randn(2**init_qubits) + 1j * rng.randn(2**init_qubits)
+    psi /= np.linalg.norm(psi)
+    rho = np.outer(psi, np.conjugate(psi))
+    rho_reshaped = rho.reshape((2,) * (init_qubits * 2))
+    keep_idxs = list(range(final_qubits))
+    rho_reduced = partial_trace(rho_reshaped, keep_idxs).reshape((2**final_qubits,) * 2)
+
+    # Direct fidelity computation (old)
+    rho1_sqrt = measures._sqrt_positive_semidefinite_matrix(rho_reduced)
+    eigs = measures.linalg.eigvalsh(rho1_sqrt @ rho_reduced @ rho1_sqrt)
+    cirq_fidelity = (np.sum(np.sqrt(np.abs(eigs)))) ** 2
+    # SVD-based fidelity (patched)
+    get_fidelity = cirq.fidelity(
+        rho_reduced, rho_reduced, validate=False, qid_shape=(2,) * final_qubits
+    )
+    # Old version should exceed 1, new should be ~1
+    assert cirq_fidelity > 1 + 1e-6
+    assert get_fidelity == pytest.approx(1, abs=1e-6)
+
+
 def test_von_neumann_entropy() -> None:
     # 1x1 matrix
     assert cirq.von_neumann_entropy(np.array([[1]])) == 0

cirq-core/cirq/qis/states.py

@@ -906,7 +906,7 @@ def validate_qid_shape(
 
     Raises:
         ValueError: if the size of `state_vector` does not match that given in
-            `qid_shape`, or if `qid_shape` is not given, if `state_vector` does
+            `qid_shape`, or if `qid_shape` is not given and `state_vector` does
             not have a dimension that is a power of two.
     """
     size = state_vector.size

cirq-core/cirq/study/result.py

@@ -144,7 +144,7 @@ def dataframe_from_measurements(measurements: Mapping[str, np.ndarray]) -> pd.Da
             converted_dict[key] = np.sum(basis * bitstrings, axis=1)
 
         # Use objects to accommodate more than 64 qubits if needed.
-        dtype = object if any(bs.shape[1] > 63 for _, bs in measurements.items()) else np.int64
+        dtype = object if any(bs.shape[1] > 63 for bs in measurements.values()) else np.int64
         return pd.DataFrame(converted_dict, dtype=dtype)
 
     @property