def add_cnot(net: network.TensorNetwork, q0: network_components.Edge,
q1: network_components.Edge
) -> Tuple[network_components.CopyNode, network_components
.Edge, network_components.Edge]:
"""Adds the CNOT quantum gate to tensor network.
CNOT consists of two rank-3 tensors: a COPY tensor on the control qubit and
a XOR tensor on the target qubit.
Args:
net: Tensor network to add CNOT to.
q0: Input edge for the control qubit.
q1: Input edge for the target qubit.
Returns:
Tuple with three elements:
- copy tensor corresponding to the control qubit
- output edge for the control qubit and
- output edge for the target qubit.
"""
control = net.add_copy_node(rank=3, dimension=2)
xor = np.array([[[1, 0], [0, 1]], [[0, 1], [1, 0]]], dtype=np.float64)
target = net.add_node(xor)
net.connect(q0, control[0])
net.connect(q1, target[0])
net.connect(control[1], target[1])
return control, control[2], target[2]
def test_backend_network(backend):
a = np.random.randn(2, 2, 2)
nodes, _, _ = ncon_interface.ncon_network([a, a, a],
[(-1, 1, 2), (1, 2, 3),
(3, -2, -3)],
backend=backend)
net = TensorNetwork(backend=backend)
# pylint: disable=expression-not-assigned
[net.add_node(n) for n in nodes]
res = naive(net).get_final_node().tensor
res_np = a.reshape((2, 4)) @ a.reshape((4, 2)) @ a.reshape((2, 4))
res_np = res_np.reshape((2, 2, 2))
np.testing.assert_allclose(res, res_np)