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catalyst.passes.to_ppr

to_ppr(qnode)[source]

A quantum compilation pass that converts Clifford+T gates into Pauli Product Rotation (PPR) gates.

Note

For improved integration with the PennyLane frontend, including inspectability with pennylane.specs(), please use pennylane.transforms.to_ppr().

Clifford gates are defined as \(\exp(-{iP\tfrac{\pi}{4}})\), where \(P\) is a Pauli word. Non-Clifford gates are defined as \(\exp(-{iP\tfrac{\pi}{8}})\).

For more information on the PPM compilation pass, check out the compilation hub.

Note

The circuits that generated from this pass are currently not executable on any backend. This pass is only for analysis with the null.qubit device and potential future execution when a suitable backend is available.

The full list of supported gates and operations are qml.H, qml.S, qml.T, qml.X, qml.Y, qml.Z, qml.adjoint(qml.S), qml.adjoint(qml.T), qml.CNOT, qml.PauliRot, and catalyst.measure.

Parameters:

fn (QNode) – QNode to apply the pass to

Returns:

QNode

Example

In this example the Clifford+T gates will be converted into PPRs.

import pennylane as qml
import catalyst

p = [("my_pipe", ["quantum-compilation-stage"])]

@qml.qjit(pipelines=p, target="mlir")
@catalyst.passes.to_ppr
@qml.qnode(qml.device("null.qubit", wires=2))
def circuit():
    qml.H(0)
    qml.CNOT([0, 1])
    qml.T(0)
    return

print(circuit.mlir_opt)

Because Catalyst does not currently support execution of Pauli-based computation operations, we must halt the pipeline after quantum-compilation-stage. This ensures that only the quantum passes will be applied to the initial MLIR, without attempting to further compile for execution.

Example MLIR Representation:

. . .
%2 = qec.ppr ["Z"](4) %1 : !quantum.bit
%3 = qec.ppr ["X"](4) %2 : !quantum.bit
%4 = qec.ppr ["Z"](4) %3 : !quantum.bit
%5 = quantum.extract %0[ 1] : !quantum.reg -> !quantum.bit
%6:2 = qec.ppr ["Z", "X"](4) %4, %5 : !quantum.bit, !quantum.bit
%7 = qec.ppr ["Z"](-4) %6#0 : !quantum.bit
%8 = qec.ppr ["X"](-4) %6#1 : !quantum.bit
%9 = qec.ppr ["Z"](8) %7 : !quantum.bit
. . .
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