From ed26d2f7ecf48b4f801e39603047a1a3c7d85632 Mon Sep 17 00:00:00 2001
From: Andreas Bengtsson <andbe@google.com>
Date: Fri, 25 Aug 2023 15:43:09 -0700
Subject: [PATCH] Fix ordering issue in
 random_rotations_between_grid_interaction_layers_circuit (#6261)

---
 .../random_quantum_circuit_generation.py      |  2 +-
 .../random_quantum_circuit_generation_test.py | 29 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/cirq-core/cirq/experiments/random_quantum_circuit_generation.py b/cirq-core/cirq/experiments/random_quantum_circuit_generation.py
index 17f57d101b3..cff89d9b8d0 100644
--- a/cirq-core/cirq/experiments/random_quantum_circuit_generation.py
+++ b/cirq-core/cirq/experiments/random_quantum_circuit_generation.py
@@ -693,5 +693,5 @@ def _two_qubit_layer(
     prng: 'np.random.RandomState',
 ) -> 'cirq.OP_TREE':
     for a, b in coupled_qubit_pairs:
-        if (a, b) in layer:
+        if (a, b) in layer or (b, a) in layer:
             yield two_qubit_op_factory(a, b, prng)
diff --git a/cirq-core/cirq/experiments/random_quantum_circuit_generation_test.py b/cirq-core/cirq/experiments/random_quantum_circuit_generation_test.py
index a035ee7c501..115bf737dc2 100644
--- a/cirq-core/cirq/experiments/random_quantum_circuit_generation_test.py
+++ b/cirq-core/cirq/experiments/random_quantum_circuit_generation_test.py
@@ -259,6 +259,30 @@ def __init__(self):
     'seed, expected_circuit_length, single_qubit_layers_slice, '
     'two_qubit_layers_slice',
     (
+        (
+            (cirq.q(0, 0), cirq.q(0, 1), cirq.q(0, 2)),
+            4,
+            lambda a, b, _: cirq.CZ(a, b),
+            [[(cirq.q(0, 0), cirq.q(0, 1))], [(cirq.q(0, 1), cirq.q(0, 2))]],
+            (cirq.X**0.5,),
+            True,
+            1234,
+            9,
+            slice(None, None, 2),
+            slice(1, None, 2),
+        ),
+        (
+            (cirq.q(0, 0), cirq.q(0, 1), cirq.q(0, 2)),
+            4,
+            lambda a, b, _: cirq.CZ(a, b),
+            [[(cirq.q(0, 1), cirq.q(0, 0))], [(cirq.q(0, 1), cirq.q(0, 2))]],
+            (cirq.X**0.5,),
+            True,
+            1234,
+            9,
+            slice(None, None, 2),
+            slice(1, None, 2),
+        ),
         (
             cirq.GridQubit.rect(4, 3),
             20,
@@ -406,7 +430,10 @@ def _validate_two_qubit_layers(
             # Operation is two-qubit
             assert cirq.num_qubits(op) == 2
             # Operation fits pattern
-            assert op.qubits in pattern[i % len(pattern)]
+            assert (
+                op.qubits in pattern[i % len(pattern)]
+                or op.qubits[::-1] in pattern[i % len(pattern)]
+            )
             active_pairs.add(op.qubits)
         # All interactions that should be in this layer are present
         assert all(