# Copyright 2019-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file 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 functools import singledispatch
from typing import Any, Dict, Optional, Set, Union
import pkg_resources
from braket.annealing.problem import Problem
from braket.circuits import Circuit
from braket.circuits.circuit_helpers import validate_circuit_and_shots
from braket.devices.braket_simulator import BraketSimulator
from braket.devices.device import Device
from braket.tasks import AnnealingQuantumTaskResult, GateModelQuantumTaskResult
from braket.tasks.local_quantum_task import LocalQuantumTask
_simulator_devices = {
entry.name: entry for entry in pkg_resources.iter_entry_points("braket.simulators")
}
[docs]class LocalSimulator(Device):
""" A simulator meant to run directly on the user's machine.
This class wraps a BraketSimulator object so that it can be run and returns
results using constructs from the SDK rather than Braket IR.
"""
def __init__(self, backend: Union[str, BraketSimulator] = "default"):
"""
Args:
backend (Union[str, BraketSimulator]): The name of the simulator backend or
the actual simulator instance to use for simulation. Defaults to the
"default" simulator backend name.
"""
delegate = _get_simulator(backend)
super().__init__(
name=delegate.__class__.__name__,
status="AVAILABLE",
status_reason="Local simulator loaded successfully",
)
self._delegate = delegate
[docs] def run(
self, task_specification: Union[Circuit, Problem], shots: int = 0, *args, **kwargs,
) -> LocalQuantumTask:
""" Runs the given task with the wrapped local simulator.
Args:
task_specification (Union[Circuit, Problem]):
shots (int, optional): The number of times to run the circuit or annealing problem.
Default is 0, which means that the simulator will compute the exact
results based on the task specification.
Sampling is not supported for shots=0.
*args: Positional args to pass to the IR simulator
**kwargs: Keyword arguments to pass to the IR simulator
Returns:
LocalQuantumTask: A LocalQuantumTask object containing the results
of the simulation
Note:
If running a circuit, the number of qubits will be passed
to the backend as the argument after the circuit itself.
Examples:
>>> circuit = Circuit().h(0).cnot(0, 1)
>>> device = LocalSimulator("default")
>>> device.run(circuit, shots=1000)
"""
result = _run_internal(task_specification, self._delegate, shots, *args, **kwargs)
return LocalQuantumTask(result)
@property
def properties(self) -> Dict[str, Any]:
""" Dict[str, Any]: Properties of the LocalSimulator device """
return self._delegate.properties
[docs] @staticmethod
def registered_backends() -> Set[str]:
""" Gets the backends that have been registered as entry points
Returns:
Set[str]: The names of the available backends that can be passed
into LocalSimulator's constructor
"""
return set(_simulator_devices.keys())
@singledispatch
def _get_simulator(simulator):
raise TypeError("Simulator must either be a string or a BraketSimulator instance")
@_get_simulator.register
def _(backend_name: str):
if backend_name in _simulator_devices:
device_class = _simulator_devices[backend_name].load()
return device_class()
else:
raise ValueError(f"Only the following devices are available {_simulator_devices.keys()}")
@_get_simulator.register
def _(backend_impl: BraketSimulator):
return backend_impl
@singledispatch
def _run_internal(
task_specification, simulator: BraketSimulator, shots: Optional[int] = None, *args, **kwargs
):
raise NotImplementedError("Unsupported task type")
@_run_internal.register
def _(circuit: Circuit, simulator: BraketSimulator, shots, *args, **kwargs):
validate_circuit_and_shots(circuit, shots)
program = circuit.to_ir()
qubits = circuit.qubit_count
results_dict = simulator.run(program, qubits, shots, *args, **kwargs)
return GateModelQuantumTaskResult.from_dict(results_dict)
@_run_internal.register
def _(problem: Problem, simulator: BraketSimulator, shots, *args, **kwargs):
ir = problem.to_ir()
results_dict = simulator.run(ir, shots, *args, *kwargs)
return AnnealingQuantumTaskResult.from_dict(results_dict)