QiskitSimulator

class QiskitSimulator(n_processes=None, shots=5000, simulation_seed=None, qiskit_backend=None, noise_model=None, track_depth=False, force_sampling=False, _deterministic_execution=False)

Bases: CircuitRunner

A parallel wrapper around Qiskit’s AerSimulator using Qiskit’s built-in parallelism.

Parameters:

• n_processes (int | None) – Number of parallel processes to use for transpilation and simulation. If None, defaults to all-but-one core (<= 16 cores) or 3/4 of cores capped at 16 (> 16 cores); 2 when not running on the main thread/process. Controls both transpilation parallelism and execution parallelism. The execution parallelism mode (circuit or shot) is automatically selected based on workload characteristics.

• shots (int) – Number of shots to perform. Defaults to 5000.

• simulation_seed (int | None) – Seed for the random number generator to ensure reproducibility. Defaults to None.

• qiskit_backend (BackendV2 | Literal['auto'] | None) – A Qiskit backend to initiate the simulator from. If "auto" is passed, the best-fit most recent fake backend will be chosen for the given circuit. Defaults to None, resulting in noiseless simulation.

• noise_model (NoiseModel | None) – Qiskit noise model to use in simulation. Defaults to None.

• track_depth (bool) – If True, record circuit depth for each submitted batch. Access via depth_history after execution. Defaults to False.

• force_sampling (bool) – If True, always use shot-based sampling even for expectation value measurements. Defaults to False.

Attributes Summary

is_async	Whether the backend executes circuits asynchronously.
n_processes	Get the current number of parallel processes.
supports_expval	Whether the backend supports expectation value measurements.

Methods Summary

estimate_run_time_batch([circuits, ...])	Estimate the execution time of a quantum circuit on a given backend, accounting for parallel gate execution.
estimate_run_time_single_circuit(circuit, ...)	Estimate the execution time of a quantum circuit on a given backend, accounting for parallel gate execution.
set_seed(seed)	Set the random seed for circuit simulation.
submit_circuits(circuits, *[, ham_ops, ...])	Submit multiple circuits for parallel simulation using Qiskit's built-in parallelism.

Attributes Documentation

is_async

Whether the backend executes circuits asynchronously.

n_processes

Get the current number of parallel processes.

Returns:

Number of parallel processes configured.

Return type:

int

supports_expval

Whether the backend supports expectation value measurements.

Methods Documentation

static estimate_run_time_batch(circuits=None, precomputed_durations=None, n_qpus=5, **transpilation_kwargs)

Estimate the execution time of a quantum circuit on a given backend, accounting for parallel gate execution.

Parameters:

• circuits (Sequence[str] | None) – The quantum circuits to estimate execution time for, as QASM strings.

• precomputed_durations (Sequence[float] | None) – A list of precomputed durations to use.

• n_qpus (int) – Number of QPU nodes in the pre-supposed cluster we are estimating runtime against.

Returns:

Estimated execution time in seconds.

Return type:

float

static estimate_run_time_single_circuit(circuit, qiskit_backend, **transpilation_kwargs)

Estimate the execution time of a quantum circuit on a given backend, accounting for parallel gate execution.

Parameters:

• circuit (str) – The quantum circuit to estimate execution time for as a QASM string.

• qiskit_backend (BackendV2 | Literal['auto']) – A Qiskit backend to use for gate time estimation.

Returns:

Estimated execution time in seconds.

Return type:

float

set_seed(seed)

Set the random seed for circuit simulation.

Parameters:

seed (int) – Seed value for the random number generator used in simulation.

submit_circuits(circuits, *, ham_ops=None, circuit_ham_map=None, shot_groups=None, cancellation_event=None, **kwargs)

Submit multiple circuits for parallel simulation using Qiskit’s built-in parallelism.

Parameters:

• circuits (Mapping[str, str]) – Dictionary mapping circuit labels to OpenQASM string representations.

• ham_ops (str | None) – Semicolon-separated Pauli string for expectation value estimation, e.g. "ZI;IZ;XX". Multiple groups can be pipe-delimited when circuit_ham_map is provided. If None, runs in sampling mode.

• circuit_ham_map (list[list[int]] | None) – Each entry is [start, end) mapping a |-group in ham_ops to a contiguous slice of circuits.

• shot_groups (list[list[int]] | None) – Per-circuit shot allocation as [start, end, shots] triples covering the iteration order of circuits. When provided, overrides self.shots for each contiguous range and triggers one aer_simulator.run call per range. Sampling-mode only — ignored when ham_ops is provided.

• cancellation_event (Event | None) – When set before this call, aborts dispatch. Aer’s .run().result() cannot be interrupted mid-batch.

• **kwargs – Additional parameters (unused, accepted for interface compatibility).

Return type:

ExecutionResult

Returns:

ExecutionResult containing either counts (sampling) or expectation values.