GroupMeasIntoBoxes

class samplomatic.transpiler.passes.GroupMeasIntoBoxes(*args, **kwargs)

Bases: TransformationPass

Collect the measurements in a circuit inside boxes.

This pass collects all of the measurements in the input circuit in boxes, together with the single-qubit gates that precede them. To assign the measurements to these boxes, it uses a greedy collection strategy that tries to collect measurements in the earliest possible box that they can fit.

Parameters:

• annotations –

  The annotations placed on the measurement boxes. The supported values are:

  • 'twirl' for a Twirl annotation.

  • 'change_basis' for a ChangeBasis annotation with mode 'measure'.

  • 'all' for both Twirl and ChangeBasis annotations.

• prefix_ref – A prefix to all the ChangeBasis.ref generated by this class. Every ref is generated by appending a counter to prefix_ref. In order to avoid collisions, the counter is shared across all the instances of this class and it is incremented every time that a new ref is created.

Note

Barriers, boxes, and multi-qubit gates that are present in the input circuit act as delimiters. This means that when one of these delimiters stands between a group of single-qubit gates and a measurement, those single-qubit gates are not added to the box.

Methods Summary

run(dag)

Collect the operations in the dag inside left-dressed boxes.

Methods Documentation

run(dag: DAGCircuit) → DAGCircuit

Collect the operations in the dag inside left-dressed boxes.

The collection strategy undertakes the following steps:

• Loop through the DAG’s op nodes in topological order.

• Group together single-qubit gate nodes and measurement nodes that need to be placed in the same box.

• Whenever a node can be placed in more than one group, place it in the earliest possible group–where “earliest” is with reference to opological ordering.

• When looping is complete, replace each group with a box.