# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2022
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""CheckerBoardTile class."""
import numpy as np
from qiskit.exceptions import QiskitError
from qiskit_qec.geometry.model.shell import Shell
from qiskit_qec.geometry.tiles.tile import Tile
from qiskit_qec.geometry.tiles.tilefactory import TileFactory
from qiskit_qec.operators.pauli_list import PauliList
# pylint: disable=anomalous-backslash-in-string)
[docs]
class CheckerBoardTile(Tile):
r"""Checker Board Tile
The diagram is as follows::
q0 q1 q1 q2
v0 v1 v0 v1
o-----o o-----o
| 0 | | 1 |
o-----o o-----o
v2 v3 v2 v3
q3 q4 q4 q5
.(0,0)
q3 q4 q4 q5
v0 v1 v0 v1
o-----o o-----o
| 2 | | 3 |
o-----o o-----o
v2 v3 v2 v3
q6 q7 q7 q8
o-----o-----o
| 0 | 1 |
o-----o-----o
| 2 | 3 |
o-----o-----o
"""
wf_operator_dict = {
"pXZXZ": [
PauliList(["XXXX"]),
PauliList(["ZZZZ"]),
PauliList(["ZZZZ"]),
PauliList(["XXXX"]),
],
"pZXZX": [
PauliList(["ZZZZ"]),
PauliList(["XXXX"]),
PauliList(["XXXX"]),
PauliList(["ZZZZ"]),
],
"cXXXX": [
PauliList(["XXXX"]),
PauliList(["XXXX"]),
PauliList(["XXXX"]),
PauliList(["XXXX"]),
],
"cZZZZ": [
PauliList(["ZZZZ"]),
PauliList(["ZZZZ"]),
PauliList(["ZZZZ"]),
PauliList(["ZZZZ"]),
],
"cXZZX": [
PauliList(["XZZX"]),
PauliList(["XZZX"]),
PauliList(["XZZX"]),
PauliList(["XZZX"]),
],
"cZXXZ": [
PauliList(["ZXXZ"]),
PauliList(["ZXXZ"]),
PauliList(["ZXXZ"]),
PauliList(["ZXXZ"]),
],
}
# Descriptions of wireframes
# qubit indices for each wireframe
wf_q_indices = [[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]
# coordinates for each wireframe vertex in path list form to enable the
# creation of the associate edges
wf_coordinates = [
[[-1, 1], [0, 1], [0, 0], [-1, 0]],
[[0, 1], [1, 1], [1, 0], [0, 0]],
[[-1, 0], [0, 0], [0, -1], [-1, -1]],
[[0, 0], [1, 0], [1, -1], [0, -1]],
]
# If the wf's are closed loops or not
wf_loop_indicator = [True, True, True, True]
# How wireframes components combine into faces/operators
faces_wf_components = [[0], [1], [2], [3]]
# Face colors (wf's inherit colors from faces)
face_colors = ["yellowgreen", "tomato", "tomato", "yellowgreen"]
num_faces = 4
size = np.array([2, 2])
num_qubits = 9
u_vec = np.array([2, 0])
v_vec = np.array([0, 2])
def __new__(
cls,
origin: np.array,
qubit_count=None,
qubit_data=None,
operators=None,
optype="pXZXZ",
) -> Shell:
r"""Creates a Checker Board Tile (Shell)
::
q0 q1 q1 q2
v0 v1 v0 v1
o-----o o-----o
| 0 | | 1 |
o-----o o-----o
v2 v3 v2 v3
q3 q4 q4 q5
.(0,0)
q3 q4 q4 q5
v0 v1 v0 v1
o-----o o-----o
| 2 | | 3 |
o-----o o-----o
v2 v3 v2 v3
q6 q7 q7 q8
o-----o-----o
| 0 | 1 |
o-----o-----o
| 2 | 3 |
o-----o-----o
Face colors for faces [0,1,2,3] are ["yellowgreen", "tomato", "tomato", "yellowgreen"]
Preformatted operators are stored in CheckerBoardTile.op_dict. Keys for op_dict are of the
form [p|c]PPPP where p = pattern and c = copy and P is a Pauli opertor X, Z or Y.
"pXZXZ" -> #0 face is Pauli("XXXX") operator, #1 face is Pauli("ZZZZ"), etc.
"cXZZX" -> #0 face is Pauli("XZZX") operator, #1 face is Pauli("XZZX"), etc.
Available precomputed operator layouts are::
"pXZXZ", "pZXZX"
"cXXXX", "cZZZZ", "cXZZX", "cZXXZ"
The operator variable may be used to define the operators specifically. The operator must be
a list of PauliList objects where each PauliList describes the opertors to be built for the
faces as indexed above 0,1,2,3, ... If the PauliList contains k Paulis then k operators will
be created for the given face.
Args:
origin (np.array): Coordinates of origin of tile (shell)
qubit_count: Qubit counter. Defaults to None.
qubit_data: Qubit data. Defaults to None.
operators: Operators for tile faces. Defaults to None.
optype (optional): Which of the listed opertor mapppings to used. Defaults to "pXZXZ".
A appropriately scalled lattice basis for tiling with the CheckerBoardTile can be accessed
from [CheckerBoardTile.u_vec, CheckerBoardTile.v_vec]
Raises:
QiskitError: Unsupported operator type
Returns:
Shell: Returns a Checker Board tile (shell) with provided origin
"""
if operators is None:
try:
operators = CheckerBoardTile.wf_operator_dict[optype]
except KeyError as key_error:
raise QiskitError(f"Unsupported operator type: {optype}") from key_error
return TileFactory(
origin=origin,
wf_coordinates=CheckerBoardTile.wf_coordinates,
wf_q_indices=CheckerBoardTile.wf_q_indices,
wf_loop_indicator=CheckerBoardTile.wf_loop_indicator,
faces_wf_components=CheckerBoardTile.faces_wf_components,
num_qubits=CheckerBoardTile.num_qubits,
face_colors=CheckerBoardTile.face_colors,
qubit_count=qubit_count,
qubit_data=qubit_data,
operators=operators,
)