GraphStateGate
class qiskit.circuit.library.GraphStateGate(adjacency_matrix)
Bases: Gate
A gate representing 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
Such a state can be prepared by first preparing all qubits in the state, then applying a 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:
from qiskit.circuit import QuantumCircuit
from qiskit.circuit.library import GraphStateGate
import rustworkx as rx
G = rx.generators.cycle_graph(5)
circuit = QuantumCircuit(5)
circuit.append(GraphStateGate(rx.adjacency_matrix(G)), [0, 1, 2, 3, 4])
circuit.decompose().draw('mpl')
References:
[1] M. Hein, J. Eisert, H.J. Briegel, Multi-party Entanglement in Graph States,
[2] D. Koh, Further Extensions of Clifford Circuits & their Classical Simulation Complexities.
Parameters
adjacency_matrix (list | np.ndarray) – input graph as n-by-n list of 0-1 lists
Raises
CircuitError – If adjacency_matrix is not symmetric.
The gate represents a graph state with the given adjacency matrix.
Attributes
adjacency_matrix
Returns the adjacency matrix.
base_class
Get the base class of this instruction. This is guaranteed to be in the inheritance tree of self.
The “base class” of an instruction is the lowest class in its inheritance tree that the object should be considered entirely compatible with for _all_ circuit applications. This typically means that the subclass is defined purely to offer some sort of programmer convenience over the base class, and the base class is the “true” class for a behavioral perspective. In particular, you should not override base_class if you are defining a custom version of an instruction that will be implemented differently by hardware, such as an alternative measurement strategy, or a version of a parametrized gate with a particular set of parameters for the purposes of distinguishing it in a Target from the full parametrized gate.
This is often exactly equivalent to type(obj), except in the case of singleton instances of standard-library instructions. These singleton instances are special subclasses of their base class, and this property will return that base. For example:
>>> isinstance(XGate(), XGate)
True
>>> type(XGate()) is XGate
False
>>> XGate().base_class is XGate
TrueIn general, you should not rely on the precise class of an instruction; within a given circuit, it is expected that Instruction.name should be a more suitable discriminator in most situations.
condition
The classical condition on the instruction.
The property qiskit.circuit.instruction.Instruction.condition is deprecated as of Qiskit 1.3.0. It will be removed in 2.0.0.
condition_bits
Get Clbits in condition.
The property qiskit.circuit.instruction.Instruction.condition_bits is deprecated as of Qiskit 1.3.0. It will be removed in 2.0.0.
decompositions
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
definition
Return definition in terms of other basic gates.
duration
Get the duration.
The property qiskit.circuit.instruction.Instruction.duration is deprecated as of Qiskit 1.3.0. It will be removed in Qiskit 2.0.0.
label
Return instruction label
mutable
Is this instance is a mutable unique instance or not.
If this attribute is False the gate instance is a shared singleton and is not mutable.
name
Return the name.
num_clbits
Return the number of clbits.
num_qubits
Return the number of qubits.
params
The parameters of this Instruction. Ideally these will be gate angles.
unit
Get the time unit of duration.
The property qiskit.circuit.instruction.Instruction.unit is deprecated as of Qiskit 1.3.0. It will be removed in Qiskit 2.0.0.