Source code for quantum_launcher.hampy.equations

 1"""
 2`equations` module provides additional binary operations for Hampy objects.
 3
 4It's goal is too simplify the creation of more complex problem implementations, by creating them with use of smaller ones.
 5"""
 6from typing import Optional
 7from copy import copy
 8from qiskit.quantum_info import SparsePauliOp
 9from .object import Equation, Variable
10
11

[docs]
12def one_in_n(variables: list[int | Variable], size: Optional[int] = None, quadratic: bool = False) -> Equation:
13    """
14    Generates Equation for One in N problem.
15
16    One in N returns True if and only if exactly one of targeted indexes in 1, and all others are 0.
17
18    Args:
19        variables (list[int  |  Variable]): Triggered variables or variable indexes
20        size (Optional[int], optional): Size of problem, if not given it takes the first found Variable.size value. Defaults to None.
21
22    Returns:
23        Equation: Equation returning True if exactly one of passed indexes is 1, False otherwise
24    """
25    if size is None:
26        for var in variable:
27            if isinstance(var, Variable):
28                size = var.size
29                break
30
31    eq = Equation(size)
32    new_variables = set()
33    for var in copy(variables):
34        if isinstance(var, int):
35            new_variables.add(eq.get_variable(var))
36        elif isinstance(var, Variable):
37            new_variables.add(eq.get_variable(var.index))
38
39    if quadratic:
40        for variable in new_variables:
41            eq += variable
42        I = SparsePauliOp.from_sparse_list([('I', [], 1)], size)
43        hamiltonian = I - eq.hamiltonian
44        return Equation(hamiltonian.compose(hamiltonian))
45
46    for variable in new_variables:
47        equation = variable
48        for different_var in new_variables - {variable}:
49            equation &= ~different_var
50        eq |= equation
51
52    return eq