convert cliffords to xz in qubit characterization (quantumlib#6420)

cirq/experiments/qubit_characterizations.py

@@ -739,13 +739,15 @@ def _two_qubit_clifford_matrices(
 
 
 def _random_single_q_clifford(
-    qubit: 'cirq.Qid', num_cfds: int, cfds: Sequence[Sequence['cirq.Gate']]
+    qubit: 'cirq.Qid', num_cfds: int, cfds: Sequence[Sequence['cirq.ops.SingleQubitCliffordGate']]
 ) -> List['cirq.Operation']:
     clifford_group_size = 24
-    operations = [[gate(qubit) for gate in gates] for gates in cfds]
+    operations = [[gate.to_phased_xz_gate()(qubit) for gate in gates] for gates in cfds]
     gate_ids = list(np.random.choice(clifford_group_size, num_cfds))
     adjoint = _reduce_gate_seq([gate for gate_id in gate_ids for gate in cfds[gate_id]]) ** -1
-    return [op for gate_id in gate_ids for op in operations[gate_id]] + [adjoint(qubit)]
+    return [op for gate_id in gate_ids for op in operations[gate_id]] + [
+        adjoint.to_phased_xz_gate()(qubit)
+    ]
 
 
 def _random_two_q_clifford(

cirq/experiments/qubit_characterizations_test.py

@@ -227,3 +227,15 @@ def test_tomography_plot_raises_for_incorrect_number_of_axes():
     with pytest.raises(ValueError):
         _, axes = plt.subplots(1, 3)
         result.plot(axes)
+
+
+def test_single_qubit_cliffords_gateset():
+    qubit = GridQubit(0, 0)
+    clifford_group = cirq.experiments.qubit_characterizations._single_qubit_cliffords()
+    c = cirq.experiments.qubit_characterizations._create_parallel_rb_circuit(
+        (qubit,), 3, clifford_group.c1_in_xy
+    )
+    device = cirq.testing.ValidatingTestDevice(
+        qubits=(qubit,), allowed_gates=(cirq.ops.PhasedXZGate, cirq.MeasurementGate)
+    )
+    device.validate_circuit(c)