Indexing

from qualtran import Bloq, CompositeBloq, BloqBuilder, Signature, Register
from qualtran import QBit, QInt, QUInt, QAny
from qualtran.drawing import show_bloq, show_call_graph, show_counts_sigma
from typing import *
import numpy as np
import sympy
import cirq

ToContiguousIndex

Build a contiguous register s from mu and nu.

\[ s = \nu (\nu + 1) / 2 + \mu \]

Assuming nu is zero indexed (in contrast to the THC paper which assumes 1, hence the slightly different formula).

Parameters

• bitsize: number of bits for mu and nu registers.

• s_bitsize: Number of bits for contiguous register.

Registers

• mu: input register

• nu: input register

• s: output contiguous register

References

• Even more efficient quantum computations of chemistry through tensor hypercontraction. Eq. 29.

from qualtran.bloqs.arithmetic.conversions import ToContiguousIndex

Example Instances

to_contg_index = ToContiguousIndex(bitsize=4, s_bitsize=8)

Graphical Signature

from qualtran.drawing import show_bloqs
show_bloqs([to_contg_index],
           ['`to_contg_index`'])

Call Graph

from qualtran.resource_counting.generalizers import ignore_split_join
to_contg_index_g, to_contg_index_sigma = to_contg_index.call_graph(max_depth=1, generalizer=ignore_split_join)
show_call_graph(to_contg_index_g)
show_counts_sigma(to_contg_index_sigma)

Counts totals:

• Toffoli: 19