--- title: PrePropagate (latest version) description: API reference for samplomatic.pre_samplex.PrePropagate in the latest version of samplomatic source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/samplomatic/auto/pre-samplex-pre-propagate --- # PrePropagate *class* `samplomatic.pre_samplex.PrePropagate(subsystems: Partition[int], direction: Direction, operation: Gate, partition: Partition[int], mode: InstructionMode, params: list[tuple[int | None, ParameterExpression]], bounded_params: list[float] | None = None, commutant_twirl: bool = False, *, trace_info: TraceInfo | None = None)` [GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/pre_samplex/graph_data.py#L248-L365) Bases: [`PreNode`](/docs/api/samplomatic/auto/pre-samplex-pre-node "samplomatic.pre_samplex.graph_data.PreNode") The propagation node type used during samplex building. **Attributes Summary** | | | | --------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------ | | [`bounded_params`](#samplomatic.pre_samplex.PrePropagate.bounded_params "samplomatic.pre_samplex.PrePropagate.bounded_params") | List of bounded params if `operation` is a fractional gate with a bounded parameter. | | [`commutant_twirl`](#samplomatic.pre_samplex.PrePropagate.commutant_twirl "samplomatic.pre_samplex.PrePropagate.commutant_twirl") | Whether this operation should be twirled with its commutant. | | [`direction`](#samplomatic.pre_samplex.PrePropagate.direction "samplomatic.pre_samplex.PrePropagate.direction") | The direction of virtual gates that can interact with this node. | | [`mode`](#samplomatic.pre_samplex.PrePropagate.mode "samplomatic.pre_samplex.PrePropagate.mode") | How the operation acts on virtual gates. | | [`operation`](#samplomatic.pre_samplex.PrePropagate.operation "samplomatic.pre_samplex.PrePropagate.operation") | The operation to propagate through. | | [`params`](#samplomatic.pre_samplex.PrePropagate.params "samplomatic.pre_samplex.PrePropagate.params") | The parameters required by the node. | | [`partition`](#samplomatic.pre_samplex.PrePropagate.partition "samplomatic.pre_samplex.PrePropagate.partition") | A partition of subsystem indices, each of which is propagated jointly. | | [`subsystems`](#samplomatic.pre_samplex.PrePropagate.subsystems "samplomatic.pre_samplex.PrePropagate.subsystems") | The subsystems that virtual gates act on. | | [`trace_info`](#samplomatic.pre_samplex.PrePropagate.trace_info "samplomatic.pre_samplex.PrePropagate.trace_info") | Debug trace information, populated when building with `debug=True`. | **Methods Summary** | | | | ------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [`from_cluster`](#samplomatic.pre_samplex.PrePropagate.from_cluster "samplomatic.pre_samplex.PrePropagate.from_cluster")(nodes) | | | [`get_style`](#samplomatic.pre_samplex.PrePropagate.get_style "samplomatic.pre_samplex.PrePropagate.get_style")() | Summarizes the style of this node when plotted via [`plot_graph()`](/docs/api/samplomatic/auto/visualization-plot-graph "samplomatic.visualization.plot_graph"). | | [`to_key`](#samplomatic.pre_samplex.PrePropagate.to_key "samplomatic.pre_samplex.PrePropagate.to_key")() | | **Attributes Documentation** ### bounded\_params Type: [`list`](https://docs.python.org/3/builtins/stdtypes.html#list)\[[`float`](https://docs.python.org/3/builtins/functions.html#float)] | [`None`](https://docs.python.org/3/builtins/constants.html#None) Default value: `None` List of bounded params if `operation` is a fractional gate with a bounded parameter. If the node involves a relevant operation with a single subsystem, the parameter is automatically extracted from the operation. ### commutant\_twirl Type: [`bool`](https://docs.python.org/3/builtins/functions.html#bool) Default value: `False` Whether this operation should be twirled with its commutant. If the operation is not a fractional gate, this value will be `False`. If it is a fractional gate, `True` signals that it should be twirled by its commutant, while `False` signals that its angle has been bound to a Clifford. ### direction Type: [`Direction`](/docs/api/samplomatic/auto/constants-direction "samplomatic.constants.Direction") Default value: `` The direction of virtual gates that can interact with this node. ### mode Type: `InstructionMode` Default value: `` How the operation acts on virtual gates. ### operation Type: [`Gate`](/docs/api/qiskit/qiskit.circuit.Gate) Default value: `` The operation to propagate through. Even when the `PrePropagate` represents more than one subsystem (i.e more than one operation) only a single common `Gate` object is stored, and possible parameters are stored elsewhere. ### params Type: [`list`](https://docs.python.org/3/builtins/stdtypes.html#list)\[[`tuple`](https://docs.python.org/3/builtins/stdtypes.html#tuple)\[[`int`](https://docs.python.org/3/builtins/functions.html#int) | [`None`](https://docs.python.org/3/builtins/constants.html#None), [`ParameterExpression`](/docs/api/qiskit/qiskit.circuit.ParameterExpression)]] Default value: `` The parameters required by the node. ### partition Type: [`Partition`](/docs/api/samplomatic/auto/partition-partition "samplomatic.partition.Partition")\[[`int`](https://docs.python.org/3/builtins/functions.html#int)] Default value: `` A partition of subsystem indices, each of which is propagated jointly. For example, a CX gate propagates pairs of single-qubit subsystems jointly. In this case, a partition would be a list of pairs of subsystem indices, where pairs are disjoint from each other. ### subsystems Type: [`Partition`](/docs/api/samplomatic/auto/partition-partition "samplomatic.partition.Partition")\[[`int`](https://docs.python.org/3/builtins/functions.html#int)] Default value: `` The subsystems that virtual gates act on. ### trace\_info Type: `TraceInfo` | [`None`](https://docs.python.org/3/builtins/constants.html#None) Default value: `None` Debug trace information, populated when building with `debug=True`. **Methods Documentation** ### from\_cluster *classmethod* `from_cluster(nodes: list[PrePropagate]) → PrePropagate` [GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/pre_samplex/graph_data.py#L319-L357) ### get\_style `get_style()` [GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/pre_samplex/graph_data.py#L301-L308) Summarizes the style of this node when plotted via [`plot_graph()`](/docs/api/samplomatic/auto/visualization-plot-graph "samplomatic.visualization.plot_graph"). ### to\_key `to_key() → PrePropagateKey` [GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/pre_samplex/graph_data.py#L310-L317)