Source code for qiskit_aer.backends.unitary_simulator

# This code is part of Qiskit.
#
# (C) Copyright IBM 2018, 2019.
#
# 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.

# pylint: disable=invalid-name
"""
Aer Unitary Simulator Backend.
"""
import copy
import logging
from warnings import warn

import psutil
from qiskit.providers.options import Options
from qiskit.providers.models import QasmBackendConfiguration

from ..aererror import AerError
from ..version import __version__
from .aerbackend import AerBackend
from .backend_utils import (
    cpp_execute_qobj,
    cpp_execute_circuits,
    available_devices,
    MAX_QUBITS_STATEVECTOR,
    LEGACY_METHOD_MAP,
    add_final_save_instruction,
    map_legacy_method_options,
    add_final_save_op,
    map_legacy_method_config,
)

# pylint: disable=import-error, no-name-in-module, abstract-method
from .controller_wrappers import aer_controller_execute

# Logger
logger = logging.getLogger(__name__)


[docs]class UnitarySimulator(AerBackend): """Ideal quantum circuit unitary simulator. **Configurable Options** The `UnitarySimulator` supports CPU and GPU simulation methods and additional configurable options. These may be set using the appropriate kwargs during initialization. They can also be set of updated using the :meth:`set_options` method. Run-time options may also be specified as kwargs using the :meth:`run` method. These will not be stored in the backend and will only apply to that execution. They will also override any previously set options. For example, to configure a a single-precision simulator .. code-block:: python backend = UnitarySimulator(precision='single') **Backend Options** The following configurable backend options are supported * ``device`` (str): Set the simulation device (Default: ``"CPU"``). Use :meth:`available_devices` to return a list of devices supported on the current system. * ``method`` (str): [DEPRECATED] Set the simulation method supported methods are ``"unitary"`` for CPU simulation, and ``"unitary_gpu"`` for GPU simulation. This option has been deprecated, use the ``device`` option to set "CPU" or "GPU" simulation instead. * ``precision`` (str): Set the floating point precision for certain simulation methods to either ``"single"`` or ``"double"`` precision (default: ``"double"``). * ``executor`` (futures.Executor): Set a custom executor for asynchronous running of simulation jobs (Default: None). * ``max_shot_size`` (int or None): If the number of shots of a noisy circuit exceeds this value simulation will be split into multi circuits for execution and the results accumulated. If ``None`` circuits will not be split based on shots. When splitting circuits use the ``max_job_size`` option to control how these split circuits should be submitted to the executor (Default: None). * ``max_shot_size`` (int or None): If the number of shots with a noise model exceeds this value, simulation will split the experiments into sub experiments in the qobj. If ``None`` simulator does nothing (Default: None). * ``"initial_unitary"`` (matrix_like): Sets a custom initial unitary matrix for the simulation instead of identity (Default: None). * ``"validation_threshold"`` (double): Sets the threshold for checking if initial unitary and target unitary are unitary matrices. (Default: 1e-8). * ``"zero_threshold"`` (double): Sets the threshold for truncating small values to zero in the result data (Default: 1e-10). * ``"max_parallel_threads"`` (int): Sets the maximum number of CPU cores used by OpenMP for parallelization. If set to 0 the maximum will be set to the number of CPU cores (Default: 0). * ``"max_parallel_experiments"`` (int): Sets the maximum number of qobj experiments that may be executed in parallel up to the max_parallel_threads value. If set to 1 parallel circuit execution will be disabled. If set to 0 the maximum will be automatically set to max_parallel_threads (Default: 1). * ``"max_memory_mb"`` (int): Sets the maximum size of memory to store a state vector. If a state vector needs more, an error is thrown. In general, a state vector of n-qubits uses 2^n complex values (16 Bytes). If set to 0, the maximum will be automatically set to the system memory size (Default: 0). * ``"statevector_parallel_threshold"`` (int): Sets the threshold that 2 * "n_qubits" must be greater than to enable OpenMP parallelization for matrix multiplication during execution of an experiment. If parallel circuit or shot execution is enabled this will only use unallocated CPU cores up to max_parallel_threads. Note that setting this too low can reduce performance (Default: 14). These backend options apply in circuit optimization passes: * ``fusion_enable`` (bool): Enable fusion optimization in circuit optimization passes [Default: True] * ``fusion_verbose`` (bool): Output gates generated in fusion optimization into metadata [Default: False] * ``fusion_max_qubit`` (int): Maximum number of qubits for a operation generated in a fusion optimization [Default: 5] * ``fusion_threshold`` (int): Threshold that number of qubits must be greater than or equal to enable fusion optimization [Default: 7] """ _DEFAULT_CONFIGURATION = { "backend_name": "unitary_simulator", "backend_version": __version__, "n_qubits": MAX_QUBITS_STATEVECTOR // 2, "url": "https://github.com/Qiskit/qiskit-aer", "simulator": True, "local": True, "conditional": False, "open_pulse": False, "memory": False, "max_shots": int(1e6), # Note that this backend will only ever # perform a single shot. This value is just # so that the default shot value for execute # will not raise an error when trying to run # a simulation "description": "A C++ unitary circuit simulator", "coupling_map": None, "basis_gates": sorted( [ "u1", "u2", "u3", "u", "p", "r", "rx", "ry", "rz", "id", "x", "y", "z", "h", "s", "sdg", "sx", "sxdg", "t", "tdg", "swap", "cx", "cy", "cz", "csx", "cu", "cp", "cu1", "cu2", "cu3", "rxx", "ryy", "rzz", "rzx", "ccx", "cswap", "mcx", "mcy", "mcz", "mcsx", "mcu", "mcp", "mcphase", "mcu1", "mcu2", "mcu3", "mcrx", "mcry", "mcrz", "mcr", "mcswap", "unitary", "diagonal", "multiplexer", "delay", "pauli", ] ), "custom_instructions": sorted(["save_unitary", "save_state", "set_unitary", "reset"]), "gates": [], } _SIMULATION_DEVICES = ("CPU", "GPU", "Thrust") _AVAILABLE_DEVICES = None def __init__(self, configuration=None, properties=None, provider=None, **backend_options): warn( "The `UnitarySimulator` backend will be deprecated in the" " future. It has been superseded by the `AerSimulator`" " backend. To obtain legacy functionality initialize with" ' `AerSimulator(method="unitary")` and append run circuits' " with the `save_state` instruction.", PendingDeprecationWarning, ) self._controller = aer_controller_execute() if UnitarySimulator._AVAILABLE_DEVICES is None: UnitarySimulator._AVAILABLE_DEVICES = available_devices(self._controller) if configuration is None: configuration = QasmBackendConfiguration.from_dict( UnitarySimulator._DEFAULT_CONFIGURATION ) else: configuration.open_pulse = False super().__init__( configuration, properties=properties, provider=provider, backend_options=backend_options ) @classmethod def _default_options(cls): return Options( # Global options shots=1, device="CPU", precision="double", executor=None, max_job_size=None, max_shot_size=None, zero_threshold=1e-10, seed_simulator=None, validation_threshold=None, max_parallel_threads=None, max_parallel_experiments=None, max_parallel_shots=None, max_memory_mb=None, fusion_enable=True, fusion_verbose=False, fusion_max_qubit=5, fusion_threshold=14, blocking_qubits=None, blocking_enable=False, # statevector options statevector_parallel_threshold=14, )
[docs] def set_option(self, key, value): if key == "method": # Handle deprecation of method option for device option warn( "The method option of the `UnitarySimulator` has been" " deprecated as of qiskit-aer 0.9.0. To run a GPU statevector" " simulation use the option `device='GPU'` instead", DeprecationWarning, ) if value in LEGACY_METHOD_MAP: value, device = LEGACY_METHOD_MAP[value] self.set_option("device", device) if value != "unitary": raise AerError("only the 'unitary' method is supported for the UnitarySimulator") return super().set_option(key, value)
[docs] def available_methods(self): """Return the available simulation methods.""" warn( "The `available_methods` method of the UnitarySimulator" " is deprecated as of qiskit-aer 0.9.0 as this simulator only" " supports a single method. To check if GPU simulation is available" " use the `available_devices` method instead.", DeprecationWarning, ) return ("unitary",)
[docs] def available_devices(self): """Return the available simulation methods.""" return copy.copy(self._AVAILABLE_DEVICES)
def _execute_qobj(self, qobj): """Execute a qobj on the backend. Args: qobj (QasmQobj): simulator input. Returns: dict: return a dictionary of results. """ # Make deepcopy so we don't modify the original qobj qobj = copy.deepcopy(qobj) qobj = add_final_save_instruction(qobj, "unitary") qobj = map_legacy_method_options(qobj) return cpp_execute_qobj(self._controller, qobj) def _execute_circuits(self, aer_circuits, noise_model, config): """Execute circuits on the backend.""" config = map_legacy_method_config(config) aer_circuits = add_final_save_op(aer_circuits, "unitary") return cpp_execute_circuits(self._controller, aer_circuits, noise_model, config) def _validate(self, qobj): """Semantic validations of the qobj which cannot be done via schemas. Some of these may later move to backend schemas. 1. Set shots=1 2. No measurements or reset 3. Check number of qubits will fit in local memory. """ name = self.name if getattr(qobj.config, "noise_model", None) is not None: raise AerError(f"{name} does not support noise.") n_qubits = qobj.config.n_qubits max_qubits = self.configuration().n_qubits if n_qubits > max_qubits: raise AerError( f"Number of qubits ({n_qubits}) is greater than " f'max ({max_qubits}) for "{name}" with ' f"{int(psutil.virtual_memory().total / (1024**3))} GB system memory." ) if qobj.config.shots != 1: logger.info('"%s" only supports 1 shot. Setting shots=1.', name) qobj.config.shots = 1 for experiment in qobj.experiments: exp_name = experiment.header.name if getattr(experiment.config, "shots", 1) != 1: logger.info( '"%s" only supports 1 shot. ' 'Setting shots=1 for circuit "%s".', name, exp_name, ) experiment.config.shots = 1 for operation in experiment.instructions: if operation.name in ["measure", "reset"]: raise AerError( f"Unsupported {name} instruction {operation.name} in circuit {exp_name}" )