Example0_Hello_World_Bell_state.py

# Copyright 2025 Xanadu Quantum Technologies Inc.

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# author: Joseph Lee (Xanadu Quantum Technologies Inc.)
"""
Simple PennyLane example creating a Bell state.
"""

import sys
import pennylane as qml

device_name = "lightning.amdgpu"

if len(sys.argv) > 1:
    if sys.argv[1].lower() == "cpu":
        device_name = "lightning.qubit"
    elif sys.argv[1].lower() == "gpu" or sys.argv[1].lower() == "amdgpu":
        device_name = "lightning.amdgpu"
    else:
        print(f"Unknown device {sys.argv[1]}, using GPU (lightning.amdgpu)")


dev = qml.device(device_name, wires=2)

@qml.qnode(dev)
def circuit():
    qml.Hadamard(wires=0)
    qml.CNOT(wires=[0,1])
    return qml.probs()

print(circuit())
print(qml.draw(circuit)())