From 8b28b839d7d2ea9f3c24d3aec490df558123176d Mon Sep 17 00:00:00 2001
From: Renato Mello <renato.msf@gmail.com>
Date: Tue, 17 Dec 2024 13:35:28 +0400
Subject: [PATCH 1/3] decompose CRY

---
 src/qibo/gates/gates.py               |  8 ++++++++
 src/qibo/transpiler/decompositions.py | 10 ++++++++++
 tests/test_gates_gates.py             |  6 ++++++
 3 files changed, 24 insertions(+)

diff --git a/src/qibo/gates/gates.py b/src/qibo/gates/gates.py
index 618279c897..1a56e8cdfb 100644
--- a/src/qibo/gates/gates.py
+++ b/src/qibo/gates/gates.py
@@ -1384,6 +1384,14 @@ def __init__(self, q0, q1, theta, trainable=True):
     def qasm_label(self):
         return "cry"
 
+    def decompose(self) -> List[Gate]:
+        """Decomposition of :math:`\\text{CRY}` gate."""
+        from qibo.transpiler.decompositions import (  # pylint: disable=C0415
+            standard_decompositions,
+        )
+
+        return standard_decompositions(self)
+
 
 class CRZ(_CRn_):
     """Controlled rotation around the Z-axis for the Bloch sphere.
diff --git a/src/qibo/transpiler/decompositions.py b/src/qibo/transpiler/decompositions.py
index 47cec5cec0..43ab7092fe 100644
--- a/src/qibo/transpiler/decompositions.py
+++ b/src/qibo/transpiler/decompositions.py
@@ -493,6 +493,16 @@ def _decomposition_generalized_RBS(ins, outs, theta, phi, controls):
 standard_decompositions.add(
     gates.CSXDG, [gates.H(1), gates.CU1(0, 1, -np.pi / 2), gates.H(1)]
 )
+standard_decompositions.add(
+    gates.CRY,
+    lambda gate: [
+        gates.RY(1, gate.parameters[0] / 4),
+        gates.CNOT(0, 1),
+        gates.RY(1, -gate.parameters[0] / 2),
+        gates.CNOT(0, 1),
+        gates.RY(1, gate.parameters[0] / 4),
+    ],
+)
 standard_decompositions.add(
     gates.RZX,
     lambda gate: [
diff --git a/tests/test_gates_gates.py b/tests/test_gates_gates.py
index f47f26d613..67fe0229f2 100644
--- a/tests/test_gates_gates.py
+++ b/tests/test_gates_gates.py
@@ -722,6 +722,12 @@ def test_cun(backend, name, params):
 
     backend.assert_allclose(final_state, target_state, atol=1e-6)
 
+    if name == "CRY":
+        decomposition = Circuit(2)
+        decomposition.add(gate.decompose())
+        decomposition = decomposition.unitary(backend=backend)
+        backend.assert_allclose(decomposition, _matrix)
+
 
 def test_swap(backend):
     final_state = apply_gates(backend, [gates.X(1), gates.SWAP(0, 1)], nqubits=2)

From 52c5c1b77cadf923e379f1aca083ad3d1e784b82 Mon Sep 17 00:00:00 2001
From: Renato Mello <renato.msf@gmail.com>
Date: Tue, 17 Dec 2024 14:37:57 +0400
Subject: [PATCH 2/3] fix test

---
 tests/test_gates_gates.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/tests/test_gates_gates.py b/tests/test_gates_gates.py
index 67fe0229f2..ed3e6cc4a3 100644
--- a/tests/test_gates_gates.py
+++ b/tests/test_gates_gates.py
@@ -698,6 +698,9 @@ def test_cun(backend, name, params):
 
     gate = getattr(gates, name)(0, 1, **params)
 
+    if name == "CRY":
+        decomposition = gate.decompose()
+
     assert gate.unitary
 
     if name != "CU2":
@@ -723,10 +726,10 @@ def test_cun(backend, name, params):
     backend.assert_allclose(final_state, target_state, atol=1e-6)
 
     if name == "CRY":
-        decomposition = Circuit(2)
-        decomposition.add(gate.decompose())
-        decomposition = decomposition.unitary(backend=backend)
-        backend.assert_allclose(decomposition, _matrix)
+        matrix = Circuit(2)
+        matrix.add(decomposition)
+        matrix = matrix.unitary(backend=backend)
+        backend.assert_allclose(matrix, _matrix)
 
 
 def test_swap(backend):

From 62bed01dc9d2efe7af4158eb0a28e6e5b50bbb4b Mon Sep 17 00:00:00 2001
From: Renato Mello <renato.msf@gmail.com>
Date: Tue, 17 Dec 2024 15:02:08 +0400
Subject: [PATCH 3/3] add tolerance

---
 tests/test_gates_gates.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/test_gates_gates.py b/tests/test_gates_gates.py
index ed3e6cc4a3..ccd04dd939 100644
--- a/tests/test_gates_gates.py
+++ b/tests/test_gates_gates.py
@@ -729,7 +729,7 @@ def test_cun(backend, name, params):
         matrix = Circuit(2)
         matrix.add(decomposition)
         matrix = matrix.unitary(backend=backend)
-        backend.assert_allclose(matrix, _matrix)
+        backend.assert_allclose(matrix, _matrix, atol=1e-10)
 
 
 def test_swap(backend):