Source code for pennylane.devices.execution_config
# Copyright 2018-2023 Xanadu Quantum Technologies Inc.
# 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.
"""
Contains the :class:`ExecutionConfig` data class.
"""
from dataclasses import dataclass, field
from typing import Optional, Union
from pennylane.workflow import SUPPORTED_INTERFACES
[docs]@dataclass
class MCMConfig:
"""A class to store mid-circuit measurement configurations."""
mcm_method: Optional[str] = None
"""Which mid-circuit measurement strategy to use. Use ``deferred`` for the deferred
measurements principle and "one-shot" if using finite shots to execute the circuit
for each shot separately. If not specified, the device will decide which method to
use."""
postselect_mode: Optional[str] = None
"""Configuration for handling shots with mid-circuit measurement postselection. If
``"hw-like"``, invalid shots will be discarded and only results for valid shots will
be returned. If ``"fill-shots"``, results corresponding to the original number of
shots will be returned. If not specified, the device will decide which mode to use."""
def __post_init__(self):
"""
Validate the configured mid-circuit measurement options.
Note that this hook is automatically called after init via the dataclass integration.
"""
if self.mcm_method not in (
"deferred",
"one-shot",
"single-branch-statistics",
"tree-traversal",
None,
):
raise ValueError(f"Invalid mid-circuit measurements method '{self.mcm_method}'.")
if self.postselect_mode not in ("hw-like", "fill-shots", "pad-invalid-samples", None):
raise ValueError(f"Invalid postselection mode '{self.postselect_mode}'.")
# pylint: disable=too-many-instance-attributes
[docs]@dataclass
class ExecutionConfig:
"""
A class to configure the execution of a quantum circuit on a device.
See the Attributes section to learn more about the various configurable options.
"""
grad_on_execution: Optional[bool] = None
"""Whether or not to compute the gradient at the same time as the execution.
If ``None``, then the device or execution pipeline can decide which one is most efficient for the situation.
"""
use_device_gradient: Optional[bool] = None
"""Whether or not to compute the gradient on the device.
``None`` indicates to use the device if possible, but to fall back to pennylane behaviour if it isn't.
True indicates a request to either use the device gradient or fail.
"""
use_device_jacobian_product: Optional[bool] = None
"""Whether or not to use the device provided vjp or jvp to compute gradients.
``None`` indicates to use the device if possible, but to fall back to the device Jacobian
or PennyLane behaviour if it isn't.
``True`` indicates to either use the device Jacobian products or fail.
"""
gradient_method: Optional[str] = None
"""The method used to compute the gradient of the quantum circuit being executed"""
gradient_keyword_arguments: Optional[dict] = None
"""Arguments used to control a gradient transform"""
device_options: Optional[dict] = None
"""Various options for the device executing a quantum circuit"""
interface: Optional[str] = None
"""The machine learning framework to use"""
derivative_order: int = 1
"""The derivative order to compute while evaluating a gradient"""
mcm_config: Union[MCMConfig, dict] = field(default_factory=MCMConfig)
"""Configuration options for handling mid-circuit measurements"""
def __post_init__(self):
"""
Validate the configured execution options.
Note that this hook is automatically called after init via the dataclass integration.
"""
if self.interface not in SUPPORTED_INTERFACES:
raise ValueError(
f"Unknown interface. interface must be in {SUPPORTED_INTERFACES}, got {self.interface} instead."
)
if self.grad_on_execution not in {True, False, None}:
raise ValueError(
f"grad_on_execution must be True, False, or None. Got {self.grad_on_execution} instead."
)
if self.device_options is None:
self.device_options = {}
if self.gradient_keyword_arguments is None:
self.gradient_keyword_arguments = {}
if isinstance(self.mcm_config, dict):
self.mcm_config = MCMConfig(**self.mcm_config)
elif not isinstance(self.mcm_config, MCMConfig):
raise ValueError(f"Got invalid type {type(self.mcm_config)} for 'mcm_config'")
DefaultExecutionConfig = ExecutionConfig()
_modules/pennylane/devices/execution_config
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