Combining readout circuits for QWC pauli strings in the measure_pauli_strings method

cirq-core/cirq/contrib/paulistring/pauli_string_measurement_with_readout_mitigation.py

@@ -25,6 +25,7 @@
 
 from cirq import circuits, ops, work
 from cirq.contrib.shuffle_circuits import run_shuffled_with_readout_benchmarking
+from cirq.experiments.single_qubit_readout_calibration import SingleQubitReadoutCalibrationResult
 from cirq.experiments.readout_confusion_matrix import TensoredConfusionMatrices
 
 if TYPE_CHECKING:
@@ -217,6 +218,31 @@ def _normalize_input_paulis(
     return cast(dict[circuits.FrozenCircuit, list[list[ops.PauliString]]], circuits_to_pauli)
 
 
+def _extract_readout_qubits(pauli_strings: list[ops.PauliString]) -> list[ops.Qid]:
+    """Extracts unique qubits from a list of QWC Pauli strings."""
+    qubits = set()
+    for pauli_str in pauli_strings:
+        for qubit in pauli_str.qubits:
+            qubits.add(qubit)
+    return sorted(qubits)
+
+
+def _build_pauli_string_calibration_result(
+    qubits_to_error: SingleQubitReadoutCalibrationResult, readout_qubits: list[ops.Qid]
+) -> SingleQubitReadoutCalibrationResult:
+    """Builds a calibration result for the specific readout qubits."""
+    return SingleQubitReadoutCalibrationResult(
+        zero_state_errors={
+            qubit: qubits_to_error.zero_state_errors[qubit] for qubit in readout_qubits
+        },
+        one_state_errors={
+            qubit: qubits_to_error.one_state_errors[qubit] for qubit in readout_qubits
+        },
+        timestamp=qubits_to_error.timestamp,
+        repetitions=qubits_to_error.repetitions,
+    )
+
+
 def _pauli_strings_to_basis_change_ops(
     pauli_strings: list[ops.PauliString], qid_list: list[ops.Qid]
 ):
@@ -315,13 +341,25 @@ def _process_pauli_measurement_results(
     for pauli_group_index, circuit_result in enumerate(circuit_results):
         measurement_results = circuit_result.measurements["m"]
         pauli_strs = pauli_string_groups[pauli_group_index]
+        pauli_readout_qubits = _extract_readout_qubits(pauli_strs)
+
+        calibration_result = (
+            calibration_results[tuple(pauli_readout_qubits)]
+            if disable_readout_mitigation is False
+            else None
+        )
 
         for pauli_str in pauli_strs:
             qubits_sorted = sorted(pauli_str.qubits)
             qubit_indices = [qubits.index(q) for q in qubits_sorted]
 
+            pauli_str_calibration_result = (
+                _build_pauli_string_calibration_result(calibration_result, qubits_sorted)
+                if disable_readout_mitigation is False
+                else None
+            )
             confusion_matrices = (
-                _build_many_one_qubits_confusion_matrix(calibration_results[tuple(qubits_sorted)])
+                _build_many_one_qubits_confusion_matrix(pauli_str_calibration_result)
                 if disable_readout_mitigation is False
                 else _build_many_one_qubits_empty_confusion_matrix(len(qubits_sorted))
             )
@@ -356,11 +394,7 @@ def _process_pauli_measurement_results(
                     mitigated_stddev=d_m_with_coefficient,
                     unmitigated_expectation=unmitigated_value_with_coefficient,
                     unmitigated_stddev=d_unmit_with_coefficient,
-                    calibration_result=(
-                        calibration_results[tuple(qubits_sorted)]
-                        if disable_readout_mitigation is False
-                        else None
-                    ),
+                    calibration_result=(pauli_str_calibration_result),
                 )
             )
 
@@ -428,8 +462,7 @@ def measure_pauli_strings(
     unique_qubit_tuples = set()
     for pauli_string_groups in normalized_circuits_to_pauli.values():
         for pauli_strings in pauli_string_groups:
-            for pauli_string in pauli_strings:
-                unique_qubit_tuples.add(tuple(sorted(pauli_string.qubits)))
+            unique_qubit_tuples.add(tuple(_extract_readout_qubits(pauli_strings)))
     # qubits_list is a list of qubit tuples
     qubits_list = sorted(unique_qubit_tuples)
 

cirq-core/cirq/contrib/paulistring/pauli_string_measurement_with_readout_mitigation_test.py

@@ -23,7 +23,7 @@
 
 import cirq
 from cirq.contrib.paulistring import measure_pauli_strings
-from cirq.experiments import SingleQubitReadoutCalibrationResult
+from cirq.experiments.single_qubit_readout_calibration import SingleQubitReadoutCalibrationResult
 from cirq.experiments.single_qubit_readout_calibration_test import NoisySingleQubitReadoutSampler