qiskit.circuit.EquivalenceLibrary

class EquivalenceLibrary(*, base=None)

A library providing a one-way mapping of Gates to their equivalent implementations as QuantumCircuits.

Create a new equivalence library.

Parameters

base (Optional[EquivalenceLibrary]) – Base equivalence library to will be referenced if an entry is not found in this library.

__init__(*, base=None)

Create a new equivalence library.

Parameters

base (Optional[EquivalenceLibrary]) – Base equivalence library to will be referenced if an entry is not found in this library.

Methods

__init__(*[, base])	Create a new equivalence library.
add_equivalence(gate, equivalent_circuit)	Add a new equivalence to the library.
draw([filename])	Draws the equivalence relations available in the library.
get_entry(gate)	Gets the set of QuantumCircuits circuits from the library which equivalently implement the given Gate.
has_entry(gate)	Check if a library contains any decompositions for gate.
set_entry(gate, entry)	Set the equivalence record for a Gate.

add_equivalence(gate, equivalent_circuit)

Add a new equivalence to the library. Future queries for the Gate will include the given circuit, in addition to all existing equivalences (including those from base).

Parameterized Gates (those including qiskit.circuit.Parameters in their Gate.params) can be marked equivalent to parameterized circuits, provided the parameters match.

Parameters

• gate (Gate) – A Gate instance.

• equivalent_circuit (QuantumCircuit) – A circuit equivalently implementing the given Gate.

draw(filename=None)

Draws the equivalence relations available in the library.

Parameters

filename (str) – An optional path to write the output image to if specified this method will return None.

Returns

Drawn equivalence library as an

IPython SVG if in a jupyter notebook, or as a PIL.Image otherwise.

Return type

PIL.Image or IPython.display.SVG

Raises

ImportError – when pydot or pillow are not installed.

get_entry(gate)

Gets the set of QuantumCircuits circuits from the library which equivalently implement the given Gate.

Parameterized circuits will have their parameters replaced with the corresponding entries from Gate.params.

Parameters

gate (Gate) – A Gate instance.

Returns

A list of equivalent QuantumCircuits. If empty,

library contains no known decompositions of Gate.

Returned circuits will be ordered according to their insertion in the library, from earliest to latest, from top to base. The ordering of the StandardEquivalenceLibrary will not generally be consistent across Qiskit versions.

Return type

List[QuantumCircuit]

has_entry(gate)

Check if a library contains any decompositions for gate.

Parameters

gate (Gate) – A Gate instance.

Returns

True if gate has a known decomposition in the library.

False otherwise.

Return type

Bool

set_entry(gate, entry)

Set the equivalence record for a Gate. Future queries for the Gate will return only the circuits provided.

Parameterized Gates (those including qiskit.circuit.Parameters in their Gate.params) can be marked equivalent to parameterized circuits, provided the parameters match.

Parameters

• gate (Gate) – A Gate instance.

• entry (List['QuantumCircuit']) – A list of QuantumCircuits, each equivalently implementing the given Gate.