LitinskiTransformation

class qiskit.transpiler.passes.LitinskiTransformation(*args, **kwargs)

Bases: TransformationPass

Applies Litinski transform to a circuit.

The transform applies to a circuit containing Clifford, single-qubit $R_Z$ -rotation, $R_X$ -rotation and $R_Y$ -rotation gates, (including $Phase$ , $T$ and $T^\dagger$ ), Pauli product rotations, Pauli product measurements, and standard $Z$ -measurements. The transform moves Clifford gates to the end of the circuit, including single-qubit rotation gates, Pauli product rotations and Pauli product measurements, whose angle is a multiple of $\pi/2$ . In the process, it transforms $R_Z$ -rotations, $R_X$ -rotation and $R_Y$ -rotation gates to Pauli product rotations, and $Z$ -measurements to Pauli product measurements.

The pass supports all of the Clifford gates in the list returned by get_clifford_gate_names():

["id", "x", "y", "z", "h", "s", "sdg", "sx", "sxdg", "cx", "cz", "cy", "swap","iswap", "ecr", "dcx"]

In addition, the rotation gates above with angles that are integral multiples of $\pi/2$ within the given tolerance are also considered Clifford.

Example:

from qiskit import generate_preset_pass_manager
from qiskit.circuit import QuantumCircuit
from qiskit.circuit.library import PauliProductMeasurement, PauliProductRotationGate
from qiskit.quantum_info import Pauli
from qiskit.transpiler.passes import LitinskiTransformation

litinski = LitinskiTransformation(fix_clifford=False, use_ppr=True)

rz_basis = ["rz", "h", "x", "cx"]
pm = generate_preset_pass_manager(basis_gates=rz_basis)
pm.optimization.append(litinski)

qc = QuantumCircuit(3, 1)
qc.h(0)
qc.rz(1.23, 0)
qc.cx(0, 1)
qc.t(1)
qc.append(PauliProductRotationGate(Pauli("XY"), 0.456), [1, 2])
qc.cx(1, 2)
qc.append(PauliProductMeasurement(Pauli("ZX")), [0, 1], [0])
qc.measure(2, 0)


pbc = pm.run(qc)

References:

[1] Litinski. A Game of Surface Codes. Quantum 3, 128 (2019)

Parameters

fix_clifford – If False (non-default), the returned circuit contains only PauliEvolution gates, with the final Clifford gates omitted. Note that in this case the operators of the original and synthesized circuits will generally not be equivalent.
insert_barrier – If True and fix_clifford=True, insert a barrier between the circuit and the final cliffords. This argument has no effect if fix_clifford=False.
use_ppr – If True, use PauliProductRotationGate to represent the Pauli rotation gates. This is encouraged to improve performance using a fully Rust-backed path. If False or None, use PauliEvolutionGate.
approximation_degree – Used in the tolerance computations, to check how much a PPR or a rotation gate is close to a Clifford. This gives the threshold for the average gate fidelity.

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)

GitHub

Execute optimization task for input Qiskit IR.

Parameters

passmanager_ir (DAGCircuit) – Qiskit IR to optimize.
state (DAGCircuit) – State associated with workflow execution by the pass manager itself.
callback (Callable[[Task, DAGCircuit, PropertySet, float, int], None] | None) – A callback function which is called per execution of optimization task.