diff --git a/neural_network/activation_functions/sinusoidal.py b/neural_network/activation_functions/sinusoidal.py
new file mode 100644
index 000000000000..830777be82f8
--- /dev/null
+++ b/neural_network/activation_functions/sinusoidal.py
@@ -0,0 +1,35 @@
+"""
+Sinusoidal activation function.
+
+Reference:
+https://arxiv.org/abs/2006.09661
+"""
+
+import numpy as np
+
+
+def sinusoidal(vector: np.ndarray, omega: float = 1.0) -> np.ndarray:
+    """
+    Apply the sinusoidal activation element-wise.
+
+    Formula: f(x) = sin(omega * x)
+
+    >>> sinusoidal(np.array([0, np.pi / 2, np.pi])).round(5)
+    array([0., 1., 0.])
+
+    >>> sinusoidal(np.array([0, np.pi / 4]), omega=2).round(5)
+    array([0., 1.])
+
+    >>> sinusoidal(np.array([])).size
+    0
+
+    >>> sinusoidal(np.array([[0, 1], [2, 3]])).shape
+    (2, 2)
+    """
+    return np.sin(omega * vector)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()