qiskit.transpiler.CouplingMap

class CouplingMap(couplinglist=None, description=None)

Directed graph specifying fixed coupling.

Nodes correspond to physical qubits (integers) and directed edges correspond to permitted CNOT gates

Create coupling graph. By default, the generated coupling has no nodes.

Paramètres

• couplinglist (list or None) – An initial coupling graph, specified as an adjacency list containing couplings, e.g. [[0,1], [0,2], [1,2]].

• description (str) – A string to describe the coupling map.

__init__(couplinglist=None, description=None)

Create coupling graph. By default, the generated coupling has no nodes.

Paramètres

• couplinglist (list or None) – An initial coupling graph, specified as an adjacency list containing couplings, e.g. [[0,1], [0,2], [1,2]].

• description (str) – A string to describe the coupling map.

Methods

__init__([couplinglist, description])	Create coupling graph.
add_edge(src, dst)	Add directed edge to coupling graph.
add_physical_qubit(physical_qubit)	Add a physical qubit to the coupling graph as a node.
distance(physical_qubit1, physical_qubit2)	Returns the undirected distance between physical_qubit1 and physical_qubit2.
draw()	Draws the coupling map.
from_full(num_qubits[, bidirectional])	Return a fully connected coupling map on n qubits.
from_grid(num_rows, num_columns[, bidirectional])	Return qubits connected on a grid of num_rows x num_columns.
from_line(num_qubits[, bidirectional])	Return a fully connected coupling map on n qubits.
from_ring(num_qubits[, bidirectional])	Return a fully connected coupling map on n qubits.
get_edges()	Gets the list of edges in the coupling graph.
is_connected()	Test if the graph is connected.
largest_connected_component()	Return a set of qubits in the largest connected component.
make_symmetric()	Convert uni-directional edges into bi-directional.
neighbors(physical_qubit)	Return the nearest neighbors of a physical qubit.
reduce(mapping)	Returns a reduced coupling map that corresponds to the subgraph of qubits selected in the mapping.
shortest_undirected_path(physical_qubit1, …)	Returns the shortest undirected path between physical_qubit1 and physical_qubit2.
size()	Return the number of physical qubits in this graph.
subgraph(nodelist)	Return a CouplingMap object for a subgraph of self.

Attributes

is_symmetric	Test if the graph is symmetric.
physical_qubits	Returns a sorted list of physical_qubits

add_edge(src, dst)

Add directed edge to coupling graph.

src (int): source physical qubit dst (int): destination physical qubit

add_physical_qubit(physical_qubit)

Add a physical qubit to the coupling graph as a node.

physical_qubit (int): An integer representing a physical qubit.

Lève

CouplingError – if trying to add duplicate qubit

distance(physical_qubit1, physical_qubit2)

Returns the undirected distance between physical_qubit1 and physical_qubit2.

Paramètres

• physical_qubit1 (int) – A physical qubit

• physical_qubit2 (int) – Another physical qubit

Renvoie

The undirected distance

Type renvoyé

int

Lève

CouplingError – if the qubits do not exist in the CouplingMap

draw()

Draws the coupling map.

This function needs pydot, which in turn needs Graphviz to be installed. Additionally, pillow will need to be installed.

Renvoie

Drawn coupling map.

Type renvoyé

PIL.Image

Lève

ImportError – when pydot or pillow are not installed.

classmethod from_full(num_qubits, bidirectional=True)

Return a fully connected coupling map on n qubits.

classmethod from_grid(num_rows, num_columns, bidirectional=True)

Return qubits connected on a grid of num_rows x num_columns.

classmethod from_line(num_qubits, bidirectional=True)

Return a fully connected coupling map on n qubits.

classmethod from_ring(num_qubits, bidirectional=True)

Return a fully connected coupling map on n qubits.

get_edges()

Gets the list of edges in the coupling graph.

Renvoie

Each edge is a pair of physical qubits.

Type renvoyé

Tuple(int,int)

is_connected()

Test if the graph is connected.

Return True if connected, False otherwise

property is_symmetric

Test if the graph is symmetric.

Return True if symmetric, False otherwise

largest_connected_component()

Return a set of qubits in the largest connected component.

make_symmetric()

Convert uni-directional edges into bi-directional.

neighbors(physical_qubit)

Return the nearest neighbors of a physical qubit.

Directionality matters, i.e. a neighbor must be reachable by going one hop in the direction of an edge.

property physical_qubits

Returns a sorted list of physical_qubits

reduce(mapping)

Returns a reduced coupling map that corresponds to the subgraph of qubits selected in the mapping.

Paramètres

mapping (list) – A mapping of reduced qubits to device qubits.

Renvoie

A reduced coupling_map for the selected qubits.

Type renvoyé

CouplingMap

Lève

CouplingError – Reduced coupling map must be connected.

shortest_undirected_path(physical_qubit1, physical_qubit2)

Returns the shortest undirected path between physical_qubit1 and physical_qubit2.

Paramètres

• physical_qubit1 (int) – A physical qubit

• physical_qubit2 (int) – Another physical qubit

Renvoie

The shortest undirected path

Type renvoyé

List

Lève

CouplingError – When there is no path between physical_qubit1, physical_qubit2.

size()

Return the number of physical qubits in this graph.

subgraph(nodelist)

Return a CouplingMap object for a subgraph of self.

nodelist (list): list of integer node labels