qrisp.quantum_backtracking.QuantumBacktrackingTree.path_decoder#

QuantumBacktrackingTree.path_decoder(h, branch_qa)[source]#

Returns the path representation for a given constellation of the h and branch_qa variables. The path representation is a list indicating which branches to take starting from the root. This function exists because the encoding of the nodes is hardware efficient but inconvenient for humans to read.

Parameters:

hinteger: The integer describing the height of the node.
branch_qalist: The list of branches to take to reach the root, starting from the node.

Returns:

list: The list of path variables to take to reach the node, starting from the root.

Examples

We create a QuantumBacktrackingTree, initiate a node and retrieve the path.

from qrisp import auto_uncompute, QuantumBool, QuantumFloat, multi_measurement
from qrisp.quantum_backtracking import QuantumBacktrackingTree

@auto_uncompute
def accept(tree):
    return QuantumBool()

@auto_uncompute
def reject(tree):
    return QuantumBool()

>>> depth = 5
>>> tree = QuantumBacktrackingTree(depth, QuantumFloat(1, name = "branch_qf*"), accept, reject)
>>> tree.init_node([1,0])
>>> multi_measurement([tree.h, tree.branch_qa])
{(3, OutcomeArray([0, 0, 0, 0, 1])): 1.0}

Retrieve the path

>>> tree.path_decoder(3, [0, 0, 0, 0, 1])
[1, 0]