From 532d5735fb19905d5e38b1d7f302d76049096eab Mon Sep 17 00:00:00 2001
From: Marco Lazzarin <48728634+mlazzarin@users.noreply.github.com>
Date: Sat, 6 Nov 2021 12:17:17 +0400
Subject: [PATCH 1/2] Fix dtype of CZ matrix

---
 src/qibo/backends/matrices.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/qibo/backends/matrices.py b/src/qibo/backends/matrices.py
index a21b7beeca..4e973c4b91 100644
--- a/src/qibo/backends/matrices.py
+++ b/src/qibo/backends/matrices.py
@@ -92,7 +92,7 @@ def _setCNOT(self):
         self._CNOT = self.backend.cast(m)
 
     def _setCZ(self):
-        m = np.diag([1, 1, 1, -1])
+        m = np.diag([1, 1, 1, -1], dtype=self.dtype)
         self._CZ = self.backend.cast(m)
 
     def _setSWAP(self):

From 4bb223742ddcabcd2ddb603f21dae8af7f23c99d Mon Sep 17 00:00:00 2001
From: Marco Lazzarin <48728634+mlazzarin@users.noreply.github.com>
Date: Sat, 6 Nov 2021 12:22:48 +0400
Subject: [PATCH 2/2] Fix previous commit

---
 src/qibo/backends/matrices.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/qibo/backends/matrices.py b/src/qibo/backends/matrices.py
index 4e973c4b91..52e6b13638 100644
--- a/src/qibo/backends/matrices.py
+++ b/src/qibo/backends/matrices.py
@@ -92,7 +92,8 @@ def _setCNOT(self):
         self._CNOT = self.backend.cast(m)
 
     def _setCZ(self):
-        m = np.diag([1, 1, 1, -1], dtype=self.dtype)
+        m = np.eye(4, dtype=self.dtype)
+        m[3, 3] = -1
         self._CZ = self.backend.cast(m)
 
     def _setSWAP(self):