Backend Configuration

A Backend is a loose term for a provider of a quantum computer or simulator.

Currently in Nexus these are specified by a BackendConfig, of which we offer the following types:

  • AerConfig: targets Qiskit Aer simulator

  • AerStateConfig: targets Qiskit Aer statevector simulator

  • AerUnitaryConfig: targets Qiskit Aer unitary simulator

  • BraketConfig: targets devices available through Amazon Braket

  • QuantinuumConfig: targets Quantinuum devices and emulators

  • IBMQConfig: targets devices available through IBMQ

  • IBMQEmulatorConfig: targets emulated devices available through IBMQ (uses a noise model for simulation)

  • ProjectQConfig: targets the ProjectQ simulator

  • QulacsConfig: targets the Qulacs simulator

from datetime import datetime

from pytket import Circuit

import qnexus as qnx

# Create a configuration to target the H2-1LE noiseless simulator
my_quantinuum_config = qnx.QuantinuumConfig(
    device_name="H2-1LE",
)

# Create a configuration to target the IBMQ Kyiv device through the open plan
my_ibmq_config = qnx.IBMQConfig(
    instance="default-us",
    project="main",
)

BackendConfigs are a required parameter when running Jobs in Nexus.

my_project_ref = qnx.projects.get_or_create(name="My Nexus Project")

my_circuit_ref = qnx.circuits.upload(
    name="My Circuit",
    circuit=Circuit(2).H(0).CX(0, 1).measure_all(),
    project=my_project_ref,
)

# Run a CompileJob targeting an IBMQ device

compile_job_IBMQ = qnx.start_compile_job(
    name=f"My IBMQ compilation job from {datetime.now()}",
    programs=[my_circuit_ref],
    backend_config=my_ibmq_config,
    project=my_project_ref,
)

compile_job_IBMQ.df()

# Run an ExecuteJob targeting the H2-1 Syntax Checker device

execute_job_H2_1LE = qnx.start_execute_job(
    name=f"My H2-1LE execution job from {datetime.now()}",
    programs=[my_circuit_ref],
    n_shots=[1000],
    backend_config=my_quantinuum_config,
    project=my_project_ref,
)

execute_job_H2_1LE.df()

Information about a particular Backend

You can find out certain features of a backend as specified by a BackendConfig, these are boolean values for the following:

  • supports_shots

  • supports_counts

  • supports_state

  • supports_unitary

  • supports_density_matrix

  • supports_expectation

  • expectation_allows_nonhermitian

  • supports_contextual_optimisation

# Check if the H2-1LE simulator support shots
qnx.devices.supports_shots(qnx.QuantinuumConfig(device_name="H2-1LE"))