GraphState¶

class
GraphState
(adjacency_matrix)[source]¶ Bases :
qiskit.circuit.quantumcircuit.QuantumCircuit
Circuit to prepare a graph state.
Given a graph G = (V, E), with the set of vertices V and the set of edges E, the corresponding graph state is defined as
\[G\rangle = \prod_{(a,b) \in E} CZ_{(a,b)} {+\rangle}^{\otimes V}\]Such a state can be prepared by first preparing all qubits in the \(+\) state, then applying a \(CZ\) gate for each corresponding graph edge.
Graph state preparation circuits are Clifford circuits, and thus easy to simulate classically. However, by adding a layer of measurements in a product basis at the end, there is evidence that the circuit becomes hard to simulate [2].
Reference Circuit:
References:
 [1] M. Hein, J. Eisert, H.J. Briegel, Multiparty Entanglement in Graph States,
 [2] D. Koh, Further Extensions of Clifford Circuits & their Classical Simulation Complexities.
Create graph state preparation circuit.
 Paramètres
adjacency_matrix (
Union
[List
,array
]) – input graph as nbyn list of 01 lists Lève
CircuitError – If adjacency_matrix is not symmetric.
The circuit prepares a graph state with the given adjacency matrix.
Attributes

ancillas
¶ Returns a list of ancilla bits in the order that the registers were added.

calibrations
¶ Return calibration dictionary.
 The custom pulse definition of a given gate is of the form
{“gate_name”: {(qubits, params): schedule}}

clbits
¶ Returns a list of classical bits in the order that the registers were added.

data
¶ Return the circuit data (instructions and context).
 Renvoie
a listlike object containing the tuples for the circuit’s data.
Each tuple is in the format
(instruction, qargs, cargs)
, where instruction is an Instruction (or subclass) object, qargs is a list of Qubit objects, and cargs is a list of Clbit objects. Type renvoyé
QuantumCircuitData

extension_lib
= 'include "qelib1.inc";'¶

global_phase
¶ Return the global phase of the circuit in radians.

header
= 'OPENQASM 2.0;'¶

instances
= 16¶

metadata
¶ The user provided metadata associated with the circuit
The metadata for the circuit is a user provided
dict
of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.

num_ancillas
¶ Return the number of ancilla qubits.

num_clbits
¶ Return number of classical bits.

num_parameters
¶ Convenience function to get the number of parameter objects in the circuit.

num_qubits
¶ Return number of qubits.

parameters
¶ Convenience function to get the parameters defined in the parameter table.

prefix
= 'circuit'¶

qubits
¶ Returns a list of quantum bits in the order that the registers were added.