StochasticSwap

class qiskit.transpiler.passes.StochasticSwap(*args, **kwargs)[source]

Bases: TransformationPass

Map a DAGCircuit onto a coupling_map adding swap gates.

Uses a randomized algorithm.

Notes

  1. Measurements may occur and be followed by swaps that result in repeated measurement of the same qubit. Near-term experiments cannot implement these circuits, so some care is required when using this mapper with experimental backend targets.

  2. We do not use the fact that the input state is zero to simplify the circuit.

StochasticSwap initializer.

The coupling map is a connected graph

If these are not satisfied, the behavior is undefined.

Parameters:

  • coupling_map (Union[CouplingMap, Target]) – Directed graph representing a coupling map.

  • trials (int) – maximum number of iterations to attempt

  • seed (int) – seed for random number generator

  • fake_run (bool) – if true, it will only pretend to do routing, i.e., no swap is effectively added.

  • initial_layout (Layout) – starting layout at beginning of pass.

Attributes

is_analysis_pass

Check if the pass is an analysis pass.

If the pass is an AnalysisPass, that means that the pass can analyze the DAG and write the results of that analysis in the property set. Modifications on the DAG are not allowed by this kind of pass.

is_transformation_pass

Check if the pass is a transformation pass.

If the pass is a TransformationPass, that means that the pass can manipulate the DAG, but cannot modify the property set (but it can be read).

Methods

execute(passmanager_ir, state, callback=None)

Execute optimization task for input Qiskit IR.

Parameters:

  • passmanager_ir (Any) – Qiskit IR to optimize.

  • state (PassManagerState) – State associated with workflow execution by the pass manager itself.

  • callback (Callable | None) – A callback function which is caller per execution of optimization task.

Returns:

Optimized Qiskit IR and state of the workflow.

Return type:

tuple[Any, qiskit.passmanager.compilation_status.PassManagerState]

name()

Name of the pass.

Return type:

str

run(dag)[source]

Run the StochasticSwap pass on dag.

Parameters:

dag (DAGCircuit) – DAG to map.

Returns:

A mapped DAG.

Return type:

DAGCircuit

Raises:

  • TranspilerError – if the coupling map or the layout are not

  • compatible with the DAG, or if the coupling_map=None –

update_status(state, run_state)

Update workflow status.

Parameters:

  • state (PassManagerState) – Pass manager state to update.

  • run_state (RunState) – Completion status of current task.

Returns:

Updated pass manager state.

Return type:

PassManagerState