rebase onto main, fix merge errors

Author: rsln-s

qokit/qaoa_circuit.py

@@ -32,6 +32,8 @@ def append_z_prod_term(qc: QuantumCircuit, indices: Sequence, gamma: float) -> N
         qc.cx(indices[0], indices[1])
     elif term_weight == 2:
         qc.rzz(2 * gamma, indices[0], indices[1])
+    elif term_weight == 1:
+        qc.rz(2 * gamma, indices[0])
     else:
         # fallback to general case
         target = indices[-1]
@@ -53,10 +55,10 @@ def append_cost_operator_circuit(qc: QuantumCircuit, terms: Sequence, gamma: flo
     gates in `append_x_term(...)`, which originates from  different conventions
     used between `QOKit` and `Qiskit`."""
     for term in terms:
-        if len(term) == 2 and isinstance(term[1], Sequence):
+        if len(term) == 2 and isinstance(term[1], (tuple, list)):
             coeff, indices = term
             append_z_prod_term(qc, indices, gamma * coeff / 2)
-        elif any([isinstance(i, tuple) for i in term]):
+        elif any([isinstance(i, (tuple, list)) for i in term]):
             raise ValueError(f"Invalid term received: {term}")
         else:
             append_z_prod_term(qc, term, gamma / 2)

tests/test_furxz_simulator.py

@@ -6,7 +6,12 @@
 from qokit.qaoa_circuit_maxcut import get_ws_qaoa_circuit
 from qokit.fur.diagonal_precomputation import precompute_vectorized_cpu_parallel
 from qiskit_aer import AerSimulator
+import os
+import pytest
 
+PYTHON_ONLY = False if os.environ.get("QOKIT_PYTHON_ONLY") is None else os.environ.get("QOKIT_PYTHON_ONLY")
+
+@pytest.mark.skipif(PYTHON_ONLY)
 def test_furxz_backends():
 
     N = 10
@@ -73,7 +78,7 @@ def test_qiskit_qokit():
     gamma, beta = get_fixed_gamma_beta(d=d,p=p)
     ini_rots = np.random.rand(N)
 
-    simclass = qokit.fur.choose_simulator_xz(name='c')
+    simclass = qokit.fur.choose_simulator_xz(name='python')
     sim = simclass(N, terms=terms)
     _result = sim.simulate_ws_qaoa(list(np.asarray(gamma)), list(np.asarray(beta)), ini_rots)
     qaoa_prob = sim.get_probabilities(_result)

tests/test_qaoa_qiskit.py

@@ -5,20 +5,23 @@
 import numpy as np
 import pandas as pd
 from qiskit_aer import AerSimulator
+from qiskit import transpile
 from pathlib import Path
-from qokit.utils import precompute_energies, obj_from_statevector, get_ramp
+from qokit.utils import precompute_energies, obj_from_statevector, get_ramp, reverse_array_index_bit_order
 from qokit.qaoa_circuit_labs import (
     get_parameterized_qaoa_circuit,
     get_qaoa_circuit,
 )
-from qokit.labs import negative_merit_factor_from_bitstring
+from qokit.qaoa_circuit import get_qaoa_circuit_from_terms
+from qokit.labs import negative_merit_factor_from_bitstring, get_terms_offset
 from qokit.utils import (
     precompute_energies,
     obj_from_statevector,
     get_ramp,
 )
-
+from qokit.fur.diagonal_precomputation import precompute_vectorized_cpu_parallel
 from qokit.qaoa_objective_labs import get_qaoa_labs_objective
+from qokit import parameter_utils
 
 test_qaoa_qiskit_folder = Path(__file__).parent
 
@@ -83,3 +86,26 @@ def test_parameterized_circuit():
 
     assert np.isclose(f1, f2)
     assert np.isclose(f1, f3)
+
+
+def test_labs_circuit_from_terms_overlap():
+    """Test that building a LABS QAOA circuit via the general get_qaoa_circuit_from_terms
+    and running it on Aer produces the expected overlap with optimal bitstrings."""
+    N = 6
+    p = 1
+
+    gamma, beta = parameter_utils.get_best_known_parameters_for_LABS_wrt_overlap_for_p(N, p)
+    terms, offset = get_terms_offset(N)
+
+    qc = get_qaoa_circuit_from_terms(N, terms, gamma, beta)
+    backend = AerSimulator(method="statevector")
+    sv = reverse_array_index_bit_order(np.array(backend.run(transpile(qc, backend)).result().get_statevector()))
+
+    diag = precompute_vectorized_cpu_parallel(terms, offset, N)
+    probs = np.abs(sv) ** 2
+    overlap = probs[diag == diag.min()].sum()
+
+    # Cross-check against stored expected overlap
+    params_df = parameter_utils.get_best_known_parameters_for_LABS_wrt_overlap(N)
+    expected_overlap = params_df[params_df["p"] == p].squeeze()["overlap"]
+    assert np.isclose(overlap, expected_overlap, atol=1e-4), f"overlap {overlap} != expected {expected_overlap}"