Register

Quantum Registers

Register(support)

A 2D register of qubits which includes their coordinates.

It is needed for e.g. analog computing. The coordinates are ignored in backends that don't need them. The easiest way to construct a register is via its classmethods like Register.triangular_lattice.

PARAMETER

DESCRIPTION

support

A graph or number of qubits. Nodes can include a "pos" attribute such that e.g.: graph.nodes = {0: {"pos": (2,3)}, 1: {"pos": (0,0)}, ...} which will be used in backends that need qubit coordinates. See the classmethods for simple construction of some predefined lattices if you don't want to build a graph manually. If you pass an integer the resulting register is the same as Register.all_to_all(n_qubits). TYPE: Graph | int

Examples:

from qadence import Register

reg = Register.honeycomb_lattice(2,3)
reg.draw()

Source code in qadence/register.py

def __init__(self, support: nx.Graph | int):
    """A 2D register of qubits which includes their coordinates.

    It is needed for e.g. analog computing.
    The coordinates are ignored in backends that don't need them. The easiest
    way to construct a register is via its classmethods like `Register.triangular_lattice`.

    Arguments:
        support: A graph or number of qubits. Nodes can include a `"pos"` attribute
            such that e.g.: `graph.nodes = {0: {"pos": (2,3)}, 1: {"pos": (0,0)}, ...}` which
            will be used in backends that need qubit coordinates.
            See the classmethods for simple construction of some predefined lattices if you
            don't want to build a graph manually.
            If you pass an integer the resulting register is the same as
            `Register.all_to_all(n_qubits)`.

    Examples:
    ```python exec="on" source="material-block" result="json"
    from qadence import Register

    reg = Register.honeycomb_lattice(2,3)
    reg.draw()
    ```
    """
    self.graph = support if isinstance(support, nx.Graph) else alltoall_graph(support)

line_graph(n_qubits, spacing=1.0)

Create graph representing linear lattice.

PARAMETER	DESCRIPTION
n_qubits	number of nodes in the graph TYPE: int

RETURNS	DESCRIPTION
Graph	graph instance

Source code in qadence/register.py

def line_graph(n_qubits: int, spacing: float = 1.0) -> nx.Graph:
    """Create graph representing linear lattice.

    Args:
        n_qubits (int): number of nodes in the graph

    Returns:
        graph instance
    """
    graph = nx.Graph()
    for i in range(n_qubits):
        graph.add_node(i, pos=(i * spacing, 0.0))
    for i, j in zip(range(n_qubits - 1), range(1, n_qubits)):
        graph.add_edge(i, j)
    return graph