add SiSWAPDG gate

src/qibo/backends/__init__.py

@@ -115,6 +115,7 @@ def create(self, dtype):
         self.SWAP = self.matrices.SWAP
         self.iSWAP = self.matrices.iSWAP
         self.SiSWAP = self.matrices.SiSWAP
+        self.SiSWAPDG = self.matrices.SiSWAPDG
         self.FSWAP = self.matrices.FSWAP
         self.ECR = self.matrices.ECR
         self.SYC = self.matrices.SYC

src/qibo/backends/npmatrices.py

@@ -206,6 +206,18 @@ def SiSWAP(self):
             dtype=self.dtype,
         )
 
+    @cached_property
+    def SiSWAPDG(self):
+        return self.np.array(
+            [
+                [1, 0, 0, 0],
+                [0, 1 / self.np.sqrt(2), -1j / self.np.sqrt(2), 0],
+                [0, -1j / self.np.sqrt(2), 1 / self.np.sqrt(2), 0],
+                [0, 0, 0, 1],
+            ],
+            dtype=self.dtype,
+        )
+
     @cached_property
     def FSWAP(self):
         return self.np.array(

src/qibo/gates/gates.py

@@ -1533,6 +1533,39 @@ def __init__(self, q0, q1):
         self.init_args = [q0, q1]
         self.unitary = True
 
+    def _dagger(self) -> "Gate":
+        return SiSWAPDG(*self.qubits)
+
+
+class SiSWAPDG(Gate):
+    """The :math:`\\sqrt{\\text{iSWAP}}}^{\\dagger}` gate.
+
+    Corresponds to the following unitary matrix
+
+    .. math::
+        \\begin{pmatrix}
+        1 & 0 & 0 & 0 \\\\
+        0 & 1/\\sqrt{2} & -i/\\sqrt{2} & 0 \\\\
+        0 & -i/\\sqrt{2} & 1/\\sqrt{2} & 0 \\\\
+        0 & 0 & 0 & 1 \\\\
+        \\end{pmatrix}
+
+    Args:
+        q0 (int): the first qubit to be swapped id number.
+        q1 (int): the second qubit to be swapped id number.
+    """
+
+    def __init__(self, q0, q1):
+        super().__init__()
+        self.name = "siswapdg"
+        self.draw_label = "sidg"
+        self.target_qubits = (q0, q1)
+        self.init_args = [q0, q1]
+        self.unitary = True
+
+    def _dagger(self) -> "Gate":
+        return SiSWAP(*self.qubits)
+
 
 class FSWAP(Gate):
     """The fermionic swap gate.

tests/test_gates_gates.py

@@ -1546,6 +1546,8 @@ def test_controlled_unitary_matrix(backend):
     ("GIVENS", (0, 1, 0.1)),
     ("RBS", (0, 1, 0.2)),
     ("ECR", (0, 1)),
+    ("SiSWAP", (0, 1)),
+    ("SiSWAPDG", (0, 1)),
 ]