Source code for pennylane_qiskit.ibmq

# Copyright 2019 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.
"""
IBMQ Device
===========

**Module name:** :mod:`pennylane_qiskit.ibmq`

.. currentmodule:: pennylane_qiskit.ibmq

This module contains the :class:`~.IBMQDevice` class, a PennyLane device that allows
evaluation and differentiation of IBM Q's Quantum Processing Units (QPUs)
using PennyLane.

Classes
-------

.. autosummary::
   IBMQDevice

Code details
~~~~~~~~~~~~
"""
import os
import warnings

from qiskit import IBMQ
from qiskit.providers.ibmq.exceptions import IBMQAccountError

from .qiskit_device import QiskitDevice


[docs]class IBMQDevice(QiskitDevice): """A PennyLane device for the IBMQ API (remote) backend. For more details, see the `Qiskit documentation <https://qiskit.org/documentation/>`_ You need to register at `IBMQ <https://quantum-computing.ibm.com/>`_ in order to recieve a token that is used for authentication using the API. As of the writing of this documentation, the API is free of charge, although there is a credit system to limit access to the quantum devices. Args: wires (int): The number of qubits of the device provider (Provider): The IBM Q provider you wish to use. If not provided, then the default provider returned by ``IBMQ.get_provider()`` is used. backend (str): the desired provider backend shots (int): number of circuit evaluations/random samples used to estimate expectation values and variances of observables Keyword Args: ibmqx_token (str): The IBM Q API token. If not provided, the environment variable ``IBMQX_TOKEN`` is used. ibmqx_url (str): The IBM Q URL. If not provided, the environment variable ``IBMQX_URL`` is used, followed by the default URL. noise_model (NoiseModel): NoiseModel Object from ``qiskit.providers.aer.noise``. Only applicable for simulator backends. """ short_name = "qiskit.ibmq"
[docs] def __init__(self, wires, provider=None, backend="ibmq_qasm_simulator", shots=1024, **kwargs): token = os.getenv("IBMQX_TOKEN") or kwargs.get("ibmqx_token", None) url = os.getenv("IBMQX_URL") or kwargs.get("ibmqx_url", None) if token is not None: # token was provided by the user, so attempt to enable an # IBM Q account manually ibmq_kwargs = {"url": url} if url is not None else {} IBMQ.enable_account(token, **ibmq_kwargs) else: # check if an IBM Q account is already active. # # * IBMQ v2 credentials stored in active_account(). # If no accounts are active, it returns None. if IBMQ.active_account() is None: # no active account try: # attempt to load a v2 account stored on disk IBMQ.load_account() except IBMQAccountError: # attempt to enable an account manually using # a provided token raise IBMQAccountError( "No active IBM Q account, and no IBM Q token provided." ) from None # IBM Q account is now enabled # get a provider p = provider or IBMQ.get_provider() super().__init__(wires=wires, provider=p, backend=backend, shots=shots, **kwargs)