Add gates.gate.CCZ

doc/source/api-reference/qibo.rst

@@ -930,6 +930,13 @@ Toffoli
     :members:
     :member-order: bysource
 
+CCZ
+"""
+
+.. autoclass:: qibo.gates.CCZ
+    :members:
+    :member-order: bysource
+
 Deutsch
 """""""
 

src/qibo/backends/__init__.py

@@ -133,6 +133,7 @@ def create(self, dtype):
         self.ECR = self.matrices.ECR
         self.SYC = self.matrices.SYC
         self.TOFFOLI = self.matrices.TOFFOLI
+        self.CCZ = self.matrices.CCZ
 
 
 matrices = QiboMatrices()

src/qibo/backends/npmatrices.py

@@ -446,6 +446,22 @@ def TOFFOLI(self):
             dtype=self.dtype,
         )
 
+    @cached_property
+    def CCZ(self):
+        return self._cast(
+            [
+                [1, 0, 0, 0, 0, 0, 0, 0],
+                [0, 1, 0, 0, 0, 0, 0, 0],
+                [0, 0, 1, 0, 0, 0, 0, 0],
+                [0, 0, 0, 1, 0, 0, 0, 0],
+                [0, 0, 0, 0, 1, 0, 0, 0],
+                [0, 0, 0, 0, 0, 1, 0, 0],
+                [0, 0, 0, 0, 0, 0, 1, 0],
+                [0, 0, 0, 0, 0, 0, 0, -1],
+            ],
+            dtype=self.dtype,
+        )
+
     def DEUTSCH(self, theta):
         sin = self.np.sin(theta) + 0j  # 0j necessary for right tensorflow dtype
         cos = self.np.cos(theta) + 0j

src/qibo/gates/gates.py

@@ -2308,6 +2308,56 @@ def congruent(self, use_toffolis: bool = True) -> List[Gate]:
         ]
 
 
+class CCZ(Gate):
+    """The controlled-CZ gate.
+
+    Corresponds to the following unitary matrix
+
+    .. math::
+        \\begin{pmatrix}
+            1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\\\
+            0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 \\\\
+            0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 \\\\
+            0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\\\
+            0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 \\\\
+            0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 \\\\
+            0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 \\\\
+            0 & 0 & 0 & 0 & 0 & 0 & 0 & -1 \\\\
+        \\end{pmatrix}
+
+    Args:
+        q0 (int): the first control qubit id number.
+        q1 (int): the second control qubit id number.
+        q2 (int): the target qubit id number.
+    """
+
+    def __init__(self, q0, q1, q2):
+        super().__init__()
+        self.name = "ccz"
+        self.draw_label = "Z"
+        self.control_qubits = (q0, q1)
+        self.target_qubits = (q2,)
+        self.init_args = [q0, q1, q2]
+        self.unitary = True
+
+    @property
+    def qasm_label(self):
+        return "ccz"
+
+    def decompose(self) -> List[Gate]:
+        """Decomposition of :math:`\\text{CCZ}` gate.
+
+        Decompose :math:`\\text{CCZ}` gate into :class:`qibo.gates.H` in
+        the target qubit, followed by :class:`qibo.gates.TOFFOLI`, followed
+        by a :class:`qibo.gates.H` in the target qubit.
+        """
+        from qibo.transpiler.decompositions import (  # pylint: disable=C0415
+            standard_decompositions,
+        )
+
+        return standard_decompositions(self)
+
+
 class DEUTSCH(ParametrizedGate):
     """The Deutsch gate.
 

src/qibo/transpiler/decompositions.py

@@ -465,3 +465,4 @@ def _u3_to_gpi2(t, p, l):
 standard_decompositions.add(
     gates.ECR, [gates.S(0), gates.SX(1), gates.CNOT(0, 1), gates.X(0)]
 )
+standard_decompositions.add(gates.CCZ, [gates.H(2), gates.TOFFOLI(0, 1, 2), gates.H(2)])

tests/test_gates_gates.py

@@ -3,7 +3,7 @@
 import numpy as np
 import pytest
 
-from qibo import gates
+from qibo import Circuit, gates, matrices
 from qibo.parameter import Parameter
 from qibo.quantum_info import random_hermitian, random_statevector, random_unitary
 
@@ -1206,6 +1206,46 @@ def test_toffoli(backend, applyx):
     assert gates.TOFFOLI(0, 1, 2).unitary
 
 
+def test_ccz(backend):
+    nqubits = 3
+    initial_state = random_statevector(2**nqubits, backend=backend)
+    final_state = apply_gates(
+        backend,
+        [gates.CCZ(0, 1, 2)],
+        nqubits=nqubits,
+        initial_state=initial_state,
+    )
+
+    matrix = np.array(
+        [
+            [1, 0, 0, 0, 0, 0, 0, 0],
+            [0, 1, 0, 0, 0, 0, 0, 0],
+            [0, 0, 1, 0, 0, 0, 0, 0],
+            [0, 0, 0, 1, 0, 0, 0, 0],
+            [0, 0, 0, 0, 1, 0, 0, 0],
+            [0, 0, 0, 0, 0, 1, 0, 0],
+            [0, 0, 0, 0, 0, 0, 1, 0],
+            [0, 0, 0, 0, 0, 0, 0, -1],
+        ],
+        dtype=np.complex128,
+    )
+    matrix = backend.cast(matrix, dtype=matrix.dtype)
+
+    target_state = matrix @ initial_state
+    backend.assert_allclose(final_state, target_state)
+
+    assert gates.CCZ(0, 1, 2).qasm_label == "ccz"
+    assert not gates.CCZ(0, 1, 2).clifford
+    assert gates.CCZ(0, 1, 2).unitary
+
+    # test decomposition
+    decomposition = Circuit(3)
+    decomposition.add(gates.CCZ(0, 1, 2).decompose())
+    decomposition = decomposition.unitary(backend)
+
+    backend.assert_allclose(decomposition, backend.cast(matrices.CCZ), atol=1e-10)
+
+
 def test_deutsch(backend):
     theta = 0.1234
     nqubits = 3