From ddc796d2d28efcaff00d31445cb7c6f8369ff3d9 Mon Sep 17 00:00:00 2001
From: "Davide Gessa (dakk)" <gessadavide@gmail.com>
Date: Fri, 18 Oct 2024 09:10:40 +0200
Subject: [PATCH] add and test cz gate

---
 qlasskit/ast2ast/astrewriter.py |  2 +-
 qlasskit/qcircuit/gates.py      |  5 +++++
 qlasskit/qcircuit/qcircuit.py   |  6 ++++++
 test/test_qcircuit_exporters.py | 21 ++++++++++++++++++++-
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/qlasskit/ast2ast/astrewriter.py b/qlasskit/ast2ast/astrewriter.py
index cd0de70..3a376d8 100644
--- a/qlasskit/ast2ast/astrewriter.py
+++ b/qlasskit/ast2ast/astrewriter.py
@@ -195,7 +195,7 @@ def visit_Subscript(self, node):  # noqa: C901
             elts = tup.elts
 
             ifex = elts[0]
-            
+
             for i, x in enumerate(elts[1:]):
                 ifex = ast.IfExp(
                     test=ast.Compare(
diff --git a/qlasskit/qcircuit/gates.py b/qlasskit/qcircuit/gates.py
index 3db633e..3f67138 100644
--- a/qlasskit/qcircuit/gates.py
+++ b/qlasskit/qcircuit/gates.py
@@ -105,6 +105,11 @@ def __init__(self):
         super().__init__(X(), 1)
 
 
+class CZ(QControlledGate):
+    def __init__(self):
+        super().__init__(Z(), 1)
+
+
 class CP(QControlledGate):
     def __init__(self):
         super().__init__(P(), 1)
diff --git a/qlasskit/qcircuit/qcircuit.py b/qlasskit/qcircuit/qcircuit.py
index 9ec788f..75f9e36 100644
--- a/qlasskit/qcircuit/qcircuit.py
+++ b/qlasskit/qcircuit/qcircuit.py
@@ -73,6 +73,7 @@ def random(qubits_n: int, depth: int, gate_list=None) -> "QCircuit":
                 gates.X,
                 gates.Z,
                 gates.Y,
+                gates.CZ,
                 gates.CX,
                 gates.CCX,
                 gates.H,
@@ -287,6 +288,11 @@ def ccx(self, w1, w2, w3):
         w1, w2, w3 = self[w1], self[w2], self[w3]
         self.append(gates.CCX(), [w1, w2, w3])
 
+    def cz(self, w1, w2):
+        """CZ gate"""
+        w1, w2 = self[w1], self[w2]
+        self.append(gates.CZ(), [w1, w2])
+
     def mctrl(self, g, wl: List[int], target, param=None):
         """Multi controlled gate"""
         target = self[target]
diff --git a/test/test_qcircuit_exporters.py b/test/test_qcircuit_exporters.py
index ecd57e0..bbaa1d7 100644
--- a/test/test_qcircuit_exporters.py
+++ b/test/test_qcircuit_exporters.py
@@ -34,6 +34,14 @@ def cx_circuit():
     return qc
 
 
+def cz_circuit():
+    qc = QCircuit()
+    a, b = qc.add_qubit(), qc.add_qubit()
+    qc.x(a)
+    qc.cz(a, b)
+    return qc
+
+
 def ccx_circuit():
     qc = QCircuit()
     a, b, c = qc.add_qubit("a"), qc.add_qubit("b"), qc.add_qubit("c")
@@ -63,6 +71,7 @@ def qft_circuit():
     ("qc", "result"),
     [
         (cx_circuit(), "gate qc q0 q1 {\n\tx q0\n\tcx q0 q1\n}\n\n"),
+        (cz_circuit(), "gate qc q0 q1 {\n\tx q0\n\tcz q0 q1\n}\n\n"),
         (ccx_circuit(), "gate qc a b c {\n\tx a\n\tx b\n\tccx a b c\n}\n\n"),
         (bell_circuit(), "gate qc a b {\n\th a\n\tcx a b\n}\n\n"),
         (
@@ -115,6 +124,7 @@ def test_export_sympy_gate(self):
     ("qc", "result"),
     [
         (cx_circuit(), {"11": 1}),
+        (cz_circuit(), {"01": 1}),
         (ccx_circuit(), {"111": 1}),
         (qft_circuit(), {"000": 1}),
     ],
@@ -136,6 +146,13 @@ def test_export_qiskit(self):
                 "q(1)": np.array([[[1]]], dtype=np.int8),
             },
         ),
+        (
+            cz_circuit(),
+            {
+                "q(0)": np.array([[[1]]], dtype=np.int8),
+                "q(1)": np.array([[[0]]], dtype=np.int8),
+            },
+        ),
         (
             ccx_circuit(),
             {
@@ -186,6 +203,7 @@ def test_export_cirq_gate(self):
     ("qc", "result", "wires"),
     [
         (cx_circuit(), [0, 0, 0, 1], 2),
+        (cz_circuit(), [0, 0, 1, 0], 2),
         (ccx_circuit(), [0, 0, 0, 0, 0, 0, 0, 1], 3),
         (bell_circuit(), [0.5, 0, 0, 0.5], 2),
         (qft_circuit(), [1, 0, 0, 0, 0, 0, 0, 0], 3),
@@ -209,6 +227,7 @@ def test_export_pennylane_circuit(self):
     ("qc", "result"),
     [
         (cx_circuit(), [0, 0, 0, 1]),
+        (cz_circuit(), [0, 0, 1, 0]),
         (ccx_circuit(), [0, 0, 0, 0, 0, 0, 0, 1]),
         (bell_circuit(), [0.70710678, 0, 0, 0.70710678]),
         (qft_circuit(), [1, 0, 0, 0, 0, 0, 0, 0]),
@@ -225,5 +244,5 @@ def test_export_qutip_circuit(self):
 
         self.assertEqual(probabilities, [1])
 
-        for i in zip(states[0].data.to_array(), self.result):
+        for i in zip(states[0].data.toarray(), self.result):
             self.assertAlmostEqual(float(i[0][0]), i[1])