StochasticSwap
class qiskit.transpiler.passes.StochasticSwap(*args, **kwargs)
Bases: TransformationPass
Map a DAGCircuit onto a coupling_map adding swap gates.
Uses a randomized algorithm.
Notes
- 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.
- 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.
The class qiskit.transpiler.passes.routing.stochastic_swap.StochasticSwap is deprecated as of qiskit 1.3. It will be removed in the 2.0 release. The StochasticSwap transpilation pass is a suboptimal routing algorithm and has been superseded by the SabreSwap pass.
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
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
run
run(dag)
Run the StochasticSwap pass on dag.
Parameters
dag (DAGCircuit) – DAG to map.
Returns
A mapped DAG.
Return type
Raises
- TranspilerError – if the coupling map or the layout are not
- compatible with the DAG**, or **if the coupling_map=None –
update_status
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