IBM Q Experience

PennyLane-Qiskit supports running PennyLane on IBM Q hardware via the qistkit.ibmq device. You can choose between different backends - either simulators tailor-made to emulate the real hardware, or the real hardware itself.

Accounts and Tokens

By default, the qiskit.ibmq device will attempt to use an already active or stored IBM Q account. If the device finds no account it will raise an error:

'No active IBM Q account, and no IBM Q token provided.

You can use the qiskit.IBMQ.save_account("<my_token>") function to permanently store an account, and the qiskit.IBMQ.load_account() function to load the stored account in a given session. Alternatively, you can specify the token with PennyLane via the PennyLane configuration file by adding the section

[qiskit.global]

  [qiskit.ibmq]
  ibmqx_token = "XXX"

You may also directly pass your IBM Q API token to the device:

dev = qml.device('qiskit.ibmq', wires=2, backend='ibmq_qasm_simulator', ibmqx_token="XXX")

Warning

Never publish code containing your token online.

Backends

By default, the qiskit.ibmq device uses the simulator backend ibmq_qasm_simulator, but this may be changed to any of the real backends as returned by

dev.capabilities()['backend']

Most of the backends of the qiskit.ibmq device, such as ibmq_london or ibmq_16_melbourne, are hardware backends. Running PennyLane with these backends means to send the circuit as a job to the actual quantum computer and retrieve the results via the cloud.

Specifying providers

Custom providers can be passed as arguments when a qiskit.ibmq device is created:

from qiskit import IBMQ
provider = IBMQ.enable_account('XYZ')

import pennylane as qml
dev = qml.device('qiskit.ibmq', wires=2, backend='ibmq_qasm_simulator', provider=provider)

If no provider is passed explicitly, then the official provider options are used, hub='ibm-q', group='open' and project='main'.

Custom provider options can also be passed as keyword arguments when creating a device:

import pennylane as qml
dev = qml.device('qiskit.ibmq', wires=2, backend='ibmq_qasm_simulator',
                 ibmqx_token='XXX', hub='MYHUB', group='MYGROUP', project='MYPROJECT')

More details on Qiskit providers can be found in the IBMQ provider documentation.