from collections.abc import Collection, Generator
from itertools import chain
from stim import Circuit
from ..detectors import Detectors
from ..layouts.layout import Layout
from ..models import Model
from .decorators import logical_measurement_x, logical_measurement_z, qec_circuit
# methods to have in this script
from .util import (
idle_iterator,
log_depolarize1_error_iterator,
log_x_error_iterator,
log_y_error_iterator,
log_z_error_iterator,
pauli_observable_x_iterator,
pauli_observable_y_iterator,
pauli_observable_z_iterator,
qubit_coords,
)
from .util import init_qubits_x0_xzzx_iterator as init_qubits_x0_iterator
from .util import init_qubits_x1_xzzx_iterator as init_qubits_x1_iterator
from .util import init_qubits_xzzx as init_qubits
from .util import init_qubits_xzzx_iterator as init_qubits_iterator
from .util import init_qubits_z0_xzzx_iterator as init_qubits_z0_iterator
from .util import init_qubits_z1_xzzx_iterator as init_qubits_z1_iterator
from .util import log_meas_x_xzzx_iterator as log_meas_x_iterator
from .util import log_meas_xzzx as log_meas
from .util import log_meas_xzzx_iterator as log_meas_iterator
from .util import log_meas_z_xzzx_iterator as log_meas_z_iterator
from .util import log_x_xzzx as log_x
from .util import log_x_xzzx_iterator as log_x_iterator
from .util import log_z_xzzx as log_z
from .util import log_z_xzzx_iterator as log_z_iterator
__all__ = [
"qubit_coords",
"idle_iterator",
"log_meas",
"log_meas_iterator",
"log_meas_z_iterator",
"log_meas_x_iterator",
"log_x",
"log_x_iterator",
"log_z",
"log_z_iterator",
"init_qubits",
"init_qubits_iterator",
"init_qubits_z0_iterator",
"init_qubits_z1_iterator",
"init_qubits_x0_iterator",
"init_qubits_x1_iterator",
"qec_round",
"qec_round_iterator",
"qec_round_pipelined",
"qec_round_pipelined_iterator",
"log_x_error_iterator",
"log_y_error_iterator",
"log_z_error_iterator",
"log_depolarize1_error_iterator",
"gate_to_iterator",
"gate_to_iterator_pipelined",
"pauli_observable_x_iterator",
"pauli_observable_y_iterator",
"pauli_observable_z_iterator",
]
[docs]
def qec_round(
model: Model,
layout: Layout,
detectors: Detectors,
anc_reset: bool = True,
anc_detectors: Collection[str] | None = None,
) -> Circuit:
"""
Returns stim circuit corresponding to a QEC round
of the given model.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
detectors
Detector object to use for their definition.
anc_reset
If ``True``, ancillas are reset at the beginning of the QEC round.
By default ``True``.
anc_detectors
List of ancilla qubits for which to define the detectors.
If ``None``, adds all detectors.
By default ``None``.
Notes
-----
This implementation follows:
https://doi.org/10.1103/PhysRevApplied.8.034021
It activates all the ancillas in ``detectors`` to always build the detectors.
As this function should not be used when building encoded circuits with
the iterating functions, it does not matter if the detectors are activated or not.
"""
circuit = sum(
qec_round_iterator(model=model, layout=layout, anc_reset=anc_reset),
start=Circuit(),
)
# add detectors
anc_qubits = layout.anc_qubits
if anc_detectors is None:
anc_detectors = anc_qubits
if set(anc_detectors) > set(anc_qubits):
raise ValueError("Elements in 'anc_detectors' are not ancilla qubits.")
# activate detectors so that "Detectors.build_from_anc" always populates
# the stim detector definitions.
inactive_dets = set(anc_detectors).difference(detectors.detectors)
detectors.activate_detectors(inactive_dets)
circuit += detectors.build_from_anc(
model.meas_target, anc_reset, anc_qubits=anc_detectors
)
return circuit
@qec_circuit
def qec_round_iterator(
model: Model,
layout: Layout,
anc_reset: bool = True,
) -> Generator[Circuit]:
"""
Yields stim circuit blocks which as a whole correspond to a QEC round
of the given model without the detectors.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
anc_reset
If ``True``, ancillas are reset at the beginning of the QEC round.
By default ``True``.
Notes
-----
This implementation follows:
https://doi.org/10.1103/PhysRevApplied.8.034021
"""
if layout.code not in ("rotated_surface_code", "rotated_surface_stability"):
raise TypeError(
f"The given layout is not a rotated surface code, but a {layout.code}"
)
data_qubits = layout.data_qubits
anc_qubits = layout.anc_qubits
qubits = set(layout.qubits)
int_order = layout.interaction_order
stab_types = list(int_order.keys())
x_stabs = layout.get_qubits(role="anc", stab_type="x_type")
yield model.incoming_noise(data_qubits)
yield model.tick()
if anc_reset:
yield model.reset(anc_qubits) + model.idle(data_qubits)
yield model.tick()
# a
directions = [int_order["x_type"][0], int_order["x_type"][3]]
rot_qubits = set(anc_qubits)
rot_qubits.update(layout.get_neighbors(x_stabs, direction=directions[0]))
rot_qubits.update(layout.get_neighbors(x_stabs, direction=directions[1]))
rot_qubits_xzzx: set[str] = set()
for direction in ("north_west", "south_east"):
stab_qubits = layout.get_qubits(role="anc", stab_type="z_type")
neighbors = layout.get_neighbors(stab_qubits, direction=direction)
rot_qubits_xzzx.update(neighbors)
rot_qubits.symmetric_difference_update(rot_qubits_xzzx)
idle_qubits = qubits - rot_qubits
yield model.hadamard(rot_qubits) + model.idle(idle_qubits)
yield model.tick()
# b
int_qubits: list[str] = []
for stab_type in stab_types:
stab_qubits = layout.get_qubits(role="anc", stab_type=stab_type)
ord_dir = int_order[stab_type][0]
int_pairs = layout.get_neighbors(stab_qubits, direction=ord_dir, as_pairs=True)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# c
yield model.hadamard(data_qubits) + model.idle(anc_qubits)
yield model.tick()
# d
int_qubits = []
for stab_type in stab_types:
stab_qubits = layout.get_qubits(role="anc", stab_type=stab_type)
ord_dir = int_order[stab_type][1]
int_pairs = layout.get_neighbors(stab_qubits, direction=ord_dir, as_pairs=True)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# e
int_qubits = []
for stab_type in stab_types:
stab_qubits = layout.get_qubits(role="anc", stab_type=stab_type)
ord_dir = int_order[stab_type][2]
int_pairs = layout.get_neighbors(stab_qubits, direction=ord_dir, as_pairs=True)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# f
yield model.hadamard(data_qubits) + model.idle(anc_qubits)
yield model.tick()
# g
int_qubits = []
for stab_type in stab_types:
stab_qubits = layout.get_qubits(role="anc", stab_type=stab_type)
ord_dir = int_order[stab_type][3]
int_pairs = layout.get_neighbors(stab_qubits, direction=ord_dir, as_pairs=True)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# h
directions = [int_order["x_type"][0], int_order["x_type"][3]]
rot_qubits = set(anc_qubits)
rot_qubits.update(layout.get_neighbors(x_stabs, direction=directions[0]))
rot_qubits.update(layout.get_neighbors(x_stabs, direction=directions[1]))
rot_qubits_xzzx = set()
for direction in ("north_west", "south_east"):
stab_qubits = layout.get_qubits(role="anc", stab_type="z_type")
neighbors = layout.get_neighbors(stab_qubits, direction=direction)
rot_qubits_xzzx.update(neighbors)
rot_qubits.symmetric_difference_update(rot_qubits_xzzx)
idle_qubits = qubits - rot_qubits
yield model.hadamard(rot_qubits) + model.idle(idle_qubits)
yield model.tick()
# i
yield model.measure(anc_qubits) + model.idle(data_qubits)
yield model.tick()
[docs]
def qec_round_pipelined(
model: Model,
layout: Layout,
detectors: Detectors,
anc_reset: bool = True,
anc_detectors: Collection[str] | None = None,
) -> Circuit:
"""
Returns stim circuit corresponding to a QEC round
of the given model.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
detectors
Detector object to use for their definition.
anc_reset
If ``True``, ancillas are reset at the beginning of the QEC round.
By default ``True``.
anc_detectors
List of ancilla qubits for which to define the detectors.
If ``None``, adds all detectors.
By default ``None``.
Notes
-----
This implementation follows:
https://doi.org/10.1103/PhysRevApplied.8.034021
It activates all the ancillas in ``detectors`` to always build the detectors.
As this function should not be used when building encoded circuits with
the iterating functions, it does not matter if the detectors are activated or not.
"""
circuit = sum(
qec_round_pipelined_iterator(model=model, layout=layout, anc_reset=anc_reset),
start=Circuit(),
)
# add detectors
anc_qubits = layout.anc_qubits
if anc_detectors is None:
anc_detectors = anc_qubits
if set(anc_detectors) > set(anc_qubits):
raise ValueError("Elements in 'anc_detectors' are not ancilla qubits.")
# activate detectors so that "Detectors.build_from_anc" always populates
# the stim detector definitions.
inactive_dets = set(anc_detectors).difference(detectors.detectors)
detectors.activate_detectors(inactive_dets)
circuit += detectors.build_from_anc(
model.meas_target, anc_reset, anc_qubits=anc_detectors
)
return circuit
@qec_circuit
def qec_round_pipelined_iterator(
model: Model,
layout: Layout,
anc_reset: bool = True,
) -> Generator[Circuit]:
"""
Yields stim circuit blocks which as a whole correspond to a QEC round
of the given model without the detectors.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
anc_reset
If ``True``, ancillas are reset at the beginning of the QEC round.
By default ``True``.
"""
if layout.code != "rotated_surface_code":
raise TypeError(
f"The given layout is not a rotated surface code, but a {layout.code}"
)
data_qubits = layout.data_qubits
anc_qubits = layout.anc_qubits
qubits = set(layout.qubits)
int_order = layout.interaction_order
stab_types = list(int_order.keys())
yield model.incoming_noise(data_qubits)
yield model.tick()
if anc_reset:
yield model.reset(anc_qubits) + model.idle(data_qubits)
yield model.tick()
for ind, stab_type in enumerate(stab_types):
stab_qubits = layout.get_qubits(role="anc", stab_type=stab_type)
rot_qubits = set(stab_qubits)
for direction in ("north_west", "south_east"):
neighbors = layout.get_neighbors(stab_qubits, direction=direction)
rot_qubits.update(neighbors)
if not ind:
idle_qubits = qubits - rot_qubits
yield model.hadamard(rot_qubits) + model.idle(idle_qubits)
yield model.tick()
for ord_dir in int_order[stab_type]:
int_pairs = layout.get_neighbors(
stab_qubits, direction=ord_dir, as_pairs=True
)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
if not ind:
yield model.hadamard(qubits)
yield model.tick()
else:
idle_qubits = qubits - rot_qubits
yield model.hadamard(rot_qubits) + model.idle(idle_qubits)
yield model.tick()
yield model.measure(anc_qubits) + model.idle(data_qubits)
yield model.tick()
def qec_round_google_with_log_meas(
model: Model,
layout: Layout,
detectors: Detectors,
anc_detectors: Collection[str] | None = None,
rot_basis: bool = False,
) -> Circuit:
"""
Returns stim circuit corresponding to a QEC round
that includes the logical measurement
of the given model. It defines the observables for
all logical qubits in the layout.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
detectors
Detector definitions to use.
anc_detectors
List of ancilla qubits for which to define the detectors.
If ``None``, adds all detectors.
By default ``None``.
rot_basis
If ``True``, the logical measurement is performed in the X basis.
If ``False``, the logical measurement is performed in the Z basis.
By deafult ``False``.
Notes
-----
The circuits are based on the following paper by Google AI:
https://doi.org/10.1038/s41586-022-05434-1
https://doi.org/10.48550/arXiv.2207.06431
It activates all the ancillas in ``detectors`` to always build the detectors.
As this function should not be used when building encoded circuits with
the iterating functions, it does not matter if the detectors are activated or not.
"""
circuit = sum(
qec_round_google_with_log_meas_iterator(
model=model, layout=layout, rot_basis=rot_basis
),
start=Circuit(),
)
# add detectors (from QEC and logical measurement)
anc_qubits = layout.anc_qubits
if anc_detectors is None:
anc_detectors = anc_qubits
if set(anc_detectors) > set(anc_qubits):
raise ValueError("Elements in 'anc_detectors' are not ancilla qubits.")
# activate detectors so that "Detectors.build_from_anc" always populates
# the stim detector definitions.
inactive_dets = set(anc_detectors).difference(detectors.detectors)
detectors.activate_detectors(inactive_dets)
circuit += detectors.build_from_anc(
model.meas_target, anc_reset=True, anc_qubits=anc_detectors
)
stab_type = "x_type" if rot_basis else "z_type"
stabs = layout.get_qubits(role="anc", stab_type=stab_type)
anc_support = layout.get_support(stabs)
detectors_stim = detectors.build_from_data(
model.meas_target,
anc_support,
anc_reset=True,
reconstructable_stabs=stabs,
anc_qubits=anc_detectors,
)
circuit += detectors_stim
# add logical observable
log_op = "log_x" if rot_basis else "log_z"
for logical_qubit in layout.logical_qubits:
log_data_qubits = layout.logical_param(log_op, logical_qubit)
targets = [model.meas_target(qubit, -1) for qubit in log_data_qubits]
circuit.append("OBSERVABLE_INCLUDE", targets, 0)
detectors.deactivate_detectors(layout.anc_qubits)
return circuit
@logical_measurement_x
@qec_circuit
def qec_round_google_with_log_x_meas_iterator(
model: Model, layout: Layout, anc_reset: bool = True
) -> Generator[Circuit]:
return qec_round_google_with_log_meas_iterator(
model, layout, rot_basis=True, anc_reset=anc_reset
)
@logical_measurement_z
@qec_circuit
def qec_round_google_with_log_z_meas_iterator(
model: Model, layout: Layout, anc_reset: bool = True
) -> Generator[Circuit]:
return qec_round_google_with_log_meas_iterator(
model, layout, rot_basis=False, anc_reset=anc_reset
)
def qec_round_google_with_log_meas_iterator(
model: Model,
layout: Layout,
rot_basis: bool = False,
anc_reset: bool = True,
) -> Generator[Circuit]:
"""
Yields stim circuit corresponding to a QEC round
that includes the logical measurement
of the given model. It defines the observables for
all logical qubits in the layout.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
rot_basis
If ``True``, the logical measurement is performed in the X basis.
If ``False``, the logical measurement is performed in the Z basis.
By deafult ``False``.
Notes
-----
The circuits are based on the following paper by Google AI:
https://doi.org/10.1038/s41586-022-05434-1
https://doi.org/10.48550/arXiv.2207.06431
"""
if layout.code != "rotated_surface_code":
raise TypeError(
f"The given layout is not a rotated surface code, but a {layout.code}"
)
if not anc_reset:
raise ValueError("'anc_reset' must be True for this iterator.")
anc_qubits = layout.anc_qubits
data_qubits = layout.data_qubits
qubits = set(layout.qubits)
# a-h
yield from coherent_qec_part_google_iterator(model=model, layout=layout)
# i (for logical measurement)
stab_type = "x_type" if rot_basis else "z_type"
stab_qubits = layout.get_qubits(role="anc", stab_type=stab_type)
yield model.hadamard(anc_qubits) + model.idle(data_qubits)
yield model.tick()
rot_qubits: set[str] = set()
for direction in ("north_west", "south_east"):
neighbors = layout.get_neighbors(stab_qubits, direction=direction)
rot_qubits.update(neighbors)
idle_qubits = qubits - rot_qubits
yield model.hadamard(rot_qubits) + model.idle(idle_qubits)
yield model.tick()
# j (for logical measurement)
yield model.measure(anc_qubits) + model.measure(data_qubits)
def coherent_qec_part_google_iterator(
model: Model, layout: Layout
) -> Generator[Circuit]:
"""
Yields stim circuit corresponding to the steps "a" to "h" from the QEC round
described in Google's paper for the given model.
Notes
-----
The circuits are based on the following paper by Google AI:
https://doi.org/10.1038/s41586-022-05434-1
https://doi.org/10.48550/arXiv.2207.06431
"""
data_qubits = layout.data_qubits
x_anc = layout.get_qubits(role="anc", stab_type="x_type")
z_anc = layout.get_qubits(role="anc", stab_type="z_type")
anc_qubits = x_anc + z_anc
qubits = set(layout.qubits)
yield model.incoming_noise(data_qubits)
yield model.tick()
# a
yield model.hadamard(anc_qubits) + model.x_gate(data_qubits)
yield model.tick()
# b
int_pairs = layout.get_neighbors(anc_qubits, direction="north_east", as_pairs=True)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# c
yield model.hadamard(data_qubits) + model.x_gate(anc_qubits)
yield model.tick()
# d
x_pairs = layout.get_neighbors(x_anc, direction="north_west", as_pairs=True)
z_pairs = layout.get_neighbors(z_anc, direction="south_east", as_pairs=True)
int_pairs = chain(x_pairs, z_pairs)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# e
yield model.x_gate(qubits)
yield model.tick()
# f
x_pairs = layout.get_neighbors(x_anc, direction="south_east", as_pairs=True)
z_pairs = layout.get_neighbors(z_anc, direction="north_west", as_pairs=True)
int_pairs = chain(x_pairs, z_pairs)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
# g
yield model.hadamard(data_qubits) + model.x_gate(anc_qubits)
yield model.tick()
# h
int_pairs = layout.get_neighbors(anc_qubits, direction="south_west", as_pairs=True)
int_qubits = list(chain.from_iterable(int_pairs))
idle_qubits = qubits - set(int_qubits)
yield model.cphase(int_qubits) + model.idle(idle_qubits)
yield model.tick()
def qec_round_google(
model: Model,
layout: Layout,
detectors: Detectors,
anc_detectors: Collection[str] | None = None,
) -> Circuit:
"""
Returns stim circuit corresponding to a QEC round
of the given model.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
detectors
Detector definitions to use.
anc_detectors
List of ancilla qubits for which to define the detectors.
If ``None``, adds all detectors.
By default ``None``.
Notes
-----
The circuits are based on the following paper by Google AI:
https://doi.org/10.1038/s41586-022-05434-1
https://doi.org/10.48550/arXiv.2207.06431
It activates all the ancillas in ``detectors`` to always build the detectors.
As this function should not be used when building encoded circuits with
the iterating functions, it does not matter if the detectors are activated or not.
"""
circuit = sum(
qec_round_google_iterator(model=model, layout=layout), start=Circuit()
)
# add detectors
anc_qubits = layout.anc_qubits
if anc_detectors is None:
anc_detectors = anc_qubits
if set(anc_detectors) > set(anc_qubits):
raise ValueError("Elements in 'anc_detectors' are not ancilla qubits.")
# activate detectors so that "Detectors.build_from_anc" always populates
# the stim detector definitions.
inactive_dets = set(anc_detectors).difference(detectors.detectors)
detectors.activate_detectors(inactive_dets)
circuit += detectors.build_from_anc(
model.meas_target, anc_reset=True, anc_qubits=anc_detectors
)
return circuit
@qec_circuit
def qec_round_google_iterator(
model: Model, layout: Layout, anc_reset: bool = True
) -> Generator[Circuit]:
"""
Yields stim circuit corresponding to a QEC round
of the given model.
Parameters
----------
model
Noise model for the gates.
layout
Code layout.
Notes
-----
The circuits are based on the following paper by Google AI:
https://doi.org/10.1038/s41586-022-05434-1
https://doi.org/10.48550/arXiv.2207.06431
"""
if layout.code != "rotated_surface_code":
raise TypeError(
f"The given layout is not a rotated surface code, but a {layout.code}"
)
if not anc_reset:
raise ValueError("'anc_reset' must be True for this iterator.")
data_qubits = layout.data_qubits
anc_qubits = layout.anc_qubits
# a-h
yield from coherent_qec_part_google_iterator(model=model, layout=layout)
# i
yield model.hadamard(anc_qubits) + model.x_gate(data_qubits)
yield model.tick()
# j
yield model.measure(anc_qubits) + model.idle(data_qubits)
yield model.tick()
yield model.reset(anc_qubits) + model.idle(data_qubits)
yield model.tick()
gate_to_iterator = {
"TICK": qec_round_iterator,
"I": idle_iterator,
"X": log_x_iterator,
"Z": log_z_iterator,
"R": init_qubits_z0_iterator,
"RZ": init_qubits_z0_iterator,
"RX": init_qubits_x0_iterator,
"M": log_meas_z_iterator,
"MZ": log_meas_z_iterator,
"MX": log_meas_x_iterator,
"X_ERROR": log_x_error_iterator,
"Y_ERROR": log_y_error_iterator,
"Z_ERROR": log_z_error_iterator,
"DEPOLARIZE1": log_depolarize1_error_iterator,
}
gate_to_iterator_pipelined = {
"TICK": qec_round_pipelined_iterator,
"I": idle_iterator,
"X": log_x_iterator,
"Z": log_z_iterator,
"R": init_qubits_z0_iterator,
"RZ": init_qubits_z0_iterator,
"RX": init_qubits_x0_iterator,
"M": log_meas_z_iterator,
"MZ": log_meas_z_iterator,
"MX": log_meas_x_iterator,
"X_ERROR": log_x_error_iterator,
"Y_ERROR": log_y_error_iterator,
"Z_ERROR": log_z_error_iterator,
"DEPOLARIZE1": log_depolarize1_error_iterator,
}
