qp.decomposition.list_decomps¶

list_decomps(op)[source]¶

Lists all stored decomposition rules for an operator class.

Note

This function is only relevant when the new experimental graph-based decomposition system (introduced in v0.41) is enabled via enable_graph(). This new way of doing decompositions is generally more resource efficient and accommodates multiple alternative decomposition rules for an operator.

Parameters:: op (type or Operator or str) – the operator or operator type to retrieve decomposition rules for. For symbolic operators, use strings like "Adjoint(RY)", "Pow(H)", "C(RX)", etc.
Returns:: a collection of decomposition rules registered for the given operator.
Return type:: DecompCollection

Example

>>> import pennylane as qp
>>> qp.list_decomps(qp.CRX)
DecompCollection([
    DecompositionRule(name=_crx_to_rx_cz),
    DecompositionRule(name=_crx_to_rz_ry),
    DecompositionRule(name=_crx_to_h_crz),
    DecompositionRule(name=_crx_to_ppr)
])
>>> print(qp.list_decomps(qp.CRX))
Available Decomposition Rules:
0: _crx_to_rx_cz
1: _crx_to_rz_ry
2: _crx_to_h_crz
3: _crx_to_ppr

Each decomposition rule can be accessed by name or by index.

>>> qp.list_decomps(qp.CRX)['_crx_to_ppr']
DecompositionRule(name=_crx_to_ppr)
>>> print(qp.list_decomps(qp.CRX)[0])
@register_resources(_crx_to_rx_cz_resources)
def _crx_to_rx_cz(phi: TensorLike, wires: WiresLike, **__):
    qp.RX(phi / 2, wires=wires[1])
    qp.CZ(wires=wires)
    qp.RX(-phi / 2, wires=wires[1])
    qp.CZ(wires=wires)
>>> print(qp.draw(qp.list_decomps(qp.CRX)[0])(0.5, wires=[0, 1]))
0: ───────────╭●────────────╭●─┤
1: ──RX(0.25)─╰Z──RX(-0.25)─╰Z─┤

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qp.decomposition.list_decomps¶

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