How to: Submit a circuit

Getting a backend

Make sure you are logged into Quantum Inspire, then use a QIDevice to fetch backends:

from qiskit_quantuminspire.qi_provider import QIProvider
from pennylane_quantuminspire.qi_device import QIDevice

# Show all current supported backends:
provider = QIProvider()
for backend in provider.backends():
    print(f"{backend.name}")

# Get Quantum Inspire's simulator backend:
emulator_backend = provider.get_backend("QX emulator")

# Instantiate a Pennylane device based on chosen backend
demo_device = QIDevice(emulator_backend)

Submitting a Circuit

Once a device has been specified, it may be used to submit circuits. For example, running a Bell State:

import pennylane as qml

@qml.qnode(demo_device)
def bell_state():
    qml.Hadamard(wires=0)
    qml.CNOT(wires=[0, 1])
    return [qml.expval(qml.Z(x)) for x in range(2)]

# Execute the circuit
result = bell_state()

# Print expectation values
print(result)

Warning

Other measurements than qml.expval() and qml.var() are only supported for backends that support measurement results for individual shots.

Support for Assembly Declaration

The pennylane-quantuminspire plugin also supports assembly declarations that can be used to add backend-specific (assembly) code to a Pennylane circuit. They are realized through an Asm instruction.

Example

import pennylane as qml
from pennylane_quantuminspire.qi_instructions import Asm

@qml.qnode(demo_device)
def quantum_function():
    qml.Hadamard(wires=0)
    Asm("TestBackend", """ a ' " {} () [] b """)
    return qml.expval(qml.PauliX(wires=[0]))

The corresponding cQASM that gets generated for this circuit looks like:

version 3.0

qubit[1] q
bit[1] b

H q[0]
asm(TestBackend) ''' a ' " {} () [] b '''
H q[0]
barrier q[0]
b[0] = measure q[0]

See the Assembly declaration documentation for more on asm instructions.