"""
Copyright 2024 Entropica Labs Pte Ltd
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""
from loom.eka import Circuit
from loom.eka.operations import ResetAllDataQubits
from .generate_syndromes import generate_syndromes
from ..interpretation_step import InterpretationStep
[docs]
def reset_all_data_qubits(
interpretation_step: InterpretationStep,
operation: ResetAllDataQubits,
same_timeslice: bool,
debug_mode: bool, # pylint: disable=unused-argument
) -> InterpretationStep:
"""
Resets all data qubits of a block to a specific SingleQubitPauliEigenstate.
It also adds empty Syndrome objects for the stabilizers will be deterministic in
the first round of syndrome measurement cycles dependent on the
initialization state. This helps to put Detectors on these deterministic
measurements when the block is measured.
NOTE: Initializing a Y state may come with some caveats, as the implementation of
the initialization may not be fault-tolerant for some codes. For example, in the
case of the Rotated Surface Code, initializing a Y state may require distillation
for it to be fault-tolerant.
Parameters
----------
interpretation_step : InterpretationStep
Interpretation step containing the blocks whose data qubits need to be reset.
operation : ResetAllDataQubits
Reset data operation description.
same_timeslice : bool
Flag indicating whether the operation is part of the same timestep as the
previous operation.
debug_mode : bool
Flag indicating whether the interpretation should be done in debug mode.
Activating debug mode will enable commutation validation for Block
Returns
-------
InterpretationStep
Interpretation step after the reset data operation.
"""
# Get the block
block_before_reset = interpretation_step.get_block(operation.input_block_name)
block = block_before_reset.rename(operation.input_block_name) # Create a new uuid
# Create a circuit that resets the data qubits to the given state
reset_circuit = Circuit(
name=f"reset all data qubits of block {block.unique_label} to "
f"|{operation.state.value}>",
circuit=[
# Reset the data qubits on the same time step
[
Circuit(
f"reset_{operation.state.value}",
channels=interpretation_step.get_channel_MUT(q),
)
for q in block.data_qubits
]
],
)
relevant_stabs = [
stab
for stab in block.stabilizers
if set(stab.pauli) == {operation.state.pauli_basis}
]
initialization_values = [
(
(1,)
if (
# The parity of the first syndrome is 1 only if:
# 1. The state is a -1 eigenstate of the corresponding pauli
# 2. The number of qubits is odd
operation.state.basis_expectation_value == -1
and len(stab.pauli) % 2 == 1
)
else ()
)
for stab in relevant_stabs
]
new_syndromes = generate_syndromes(
interpretation_step=interpretation_step,
stabilizers=relevant_stabs,
block=block,
stab_measurements=list(initialization_values),
)
interpretation_step.append_syndromes_MUT(new_syndromes)
# Add the reset circuit to the interpretation step
interpretation_step.append_circuit_MUT(reset_circuit, same_timeslice)
# Change the block history
interpretation_step.update_block_history_and_evolution_MUT(
old_blocks=(block_before_reset,),
new_blocks=(block,),
update_evolution=False,
)
# Return the new interpretation step
return interpretation_step