iSWAP gate and Givens gate

src/tequila/circuit/gates.py

@@ -504,6 +504,71 @@ def SWAP(first: int, second: int, control: typing.Union[int, list] = None, power
     else:
         return GeneralizedRotation(angle=power * np.pi, control=control, generator=generator,
                                    eigenvalues_magnitude=0.25)
+
+
+def iSWAP(first: int, second: int, control: typing.Union[int, list] = None, power: float = 1.0, *args,
+         **kwargs) -> QCircuit:
+    """
+    Notes
+    ----------
+    iSWAP gate
+    .. math::
+        iSWAP = e^{i\\frac{\\pi}{4} (X \\otimes X + Y \\otimes Y )}
+
+    Parameters
+    ----------
+    first: int
+        target qubit
+    second: int
+        target qubit
+    control
+        int or list of ints
+    power
+        numeric type (fixed exponent) or hashable type (parametrized exponent)
+
+    Returns
+    -------
+    QCircuit
+
+    """
+
+    generator = paulis.from_string(f"X({first})X({second}) + Y({first})Y({second})")
+
+    p0 = paulis.Projector("|00>") + paulis.Projector("|11>")
+    p0 = p0.map_qubits({0:first, 1:second})
+
+    gate = QubitExcitationImpl(angle=power*(-np.pi/2), target=generator.qubits, generator=generator, p0=p0, control=control, compile_options="vanilla", *args, **kwargs)
+
+    return QCircuit.wrap_gate(gate)
+
+
+def Givens(first: int, second: int, control: typing.Union[int, list] = None, angle: float = None, *args,
+         **kwargs) -> QCircuit:
+    """
+    Notes
+    ----------
+    Givens gate G
+    .. math::
+        G = e^{-i\\theta \\frac{(Y \\otimes X - X \\otimes Y )}{2}}
+
+    Parameters
+    ----------
+    first: int
+        target qubit
+    second: int
+        target qubit
+    control
+        int or list of ints
+    angle
+        numeric type (fixed exponent) or hashable type (parametrized exponent), theta in the above formula
+
+    Returns
+    -------
+    QCircuit
+
+    """
+
+    return QubitExcitation(target=[second,first], angle=2*angle, control=control, *args, **kwargs)  # twice the angle since theta is not divided by two in the matrix exponential
 
 
 """

tests/test_circuits.py

@@ -6,7 +6,7 @@
 from tequila import assign_variable, paulis, TequilaWarning
 from tequila.circuit._gates_impl import RotationGateImpl
 from tequila.circuit.gates import CNOT, ExpPauli, H, Phase, QCircuit, RotationGate, Rx, Ry, Rz, S, \
-    SWAP, T, Trotterized, u1, u2, u3, X, Y, Z
+    SWAP, iSWAP, Givens, T, Trotterized, u1, u2, u3, X, Y, Z
 from tequila.objective.objective import Variable
 from tequila.simulators.simulator_api import simulate
 from tequila.wavefunction.qubit_wavefunction import QubitWaveFunction
@@ -332,6 +332,31 @@ def test_swap():
     wfn = simulate(U)
     wfnx = simulate(X(2)+X(3))
     assert numpy.isclose(numpy.abs(wfn.inner(wfnx))**2,1.0)
+
+def test_iswap():
+    U = X(0)
+    U += iSWAP(0, 2, power=0.5)
+    wfn = simulate(U)
+    wfnx = simulate(X(2))
+    assert numpy.isclose(numpy.abs(wfn.inner(wfnx))**2, 0.5)
+
+
+def test_givens():
+    U = X(0)
+    U += Givens(0, 1, angle=-numpy.pi/4)
+    wfn = simulate(U)
+    wfnx = simulate(X(0))
+    assert numpy.isclose(numpy.abs(wfn.inner(wfnx))**2, 0.5)
+    wfnx = simulate(X(1))
+    assert numpy.isclose(numpy.abs(wfn.inner(wfnx))**2, 0.5)
+
+    U = X(0)
+    U += Givens(0, 1, angle=numpy.pi/4)
+    wfn = simulate(U)
+    wfnx0 = simulate(Phase([0, 1], angle=numpy.pi) + X(0))
+    wfnx1 = simulate(X(1))
+    assert numpy.isclose(wfn.inner(wfnx0), -wfn.inner(wfnx1))
+
 
 def test_variable_map():
     U = Ry(angle="a", target=0) + Rx(angle="b", target=1) + Rz(angle="c", target=2) + H(angle="d", target=3) + ExpPauli(paulistring="X(0)Y(1)Z(2)", angle="e")