Backends

Divi programs take a backend= argument. Switching between a laptop, Qoro’s cloud simulators, and real QPUs only means changing that argument.

Backend	Runs on	Notes
MaestroSimulator	Your machine	The default. Uses Maestro in-process. Supports all of Maestro’s simulation methods, native expectation values, and Maestro noise models.
QiskitSimulator	Your machine	Qiskit Aer, including fake-backend noise profiles (aer extra).
QoroService	Qoro’s cloud (Composer)	Simulator clusters or QPU systems, selected per job.

Local: MaestroSimulator

Runs circuits through Maestro’s Python bindings. It defaults to the CPU statevector method. A MaestroConfig selects another method, such as MPS for wide low-entanglement circuits, a density matrix or MPO for exact noise channels, or a GPU backend if the plugin is installed. A maestro.NoiseModel can be attached for noisy simulation. See Maestro.

Cloud: QoroService

QoroService reads an API token (QORO_API_KEY, created at dash.qoroquantum.net) and talks to the Composer API. Per job, a JobConfig chooses:

• The target. A simulator_cluster or a qpu_system. Every account can use both the CPU and the GPU simulator clusters; the dashboard’s Clusters page lists their names, and the default is qoro_maestro. Any account can also target a QPU system registered with its own IBM, IQM, or Braket credentials.
• Shots, and whether to use circuit packing on QPUs.
• Simulator settings through a MaestroConfig, such as a fixed simulation method or noise, or device settings through a DeviceConfig with vendor-specific options, such as IBM layout and mitigation settings. A job uses one or the other, never both.

What happens on the cloud side:

• On simulator clusters, expectation values are computed by Maestro, so Divi sends Pauli observables instead of measurement circuits. You can force sampling with JobConfig(force_sampling=True). QPU targets always sample.
• Variational programs upload a single parametric template and many parameter sets, which are bound on the server.
• Divi uploads in chunks, polls job status, pages through results, and maps platform errors (insufficient credits, timeouts, failures) to typed exceptions.

The divi-config-helper command saves default targets and settings, so scripts don’t have to repeat them.

📖 Code examples and the full configuration reference: divi.readthedocs.io.