Source code for qiskit_experiments.library.calibration.fine_frequency_cal

# This code is part of Qiskit.
#
# (C) Copyright IBM 2021.
#
# 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.
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"""Fine frequency calibration experiment."""

from typing import Dict, List, Optional, Sequence
import numpy as np

from qiskit.providers.backend import Backend
from qiskit.circuit import QuantumCircuit

from qiskit_experiments.framework import ExperimentData
from qiskit_experiments.calibration_management.update_library import BaseUpdater
from qiskit_experiments.calibration_management import (
    BaseCalibrationExperiment,
    Calibrations,
)
from qiskit_experiments.library.characterization.fine_frequency import FineFrequency


[docs] class FineFrequencyCal(BaseCalibrationExperiment, FineFrequency): """A calibration version of the fine frequency experiment.""" def __init__( self, physical_qubits: Sequence[int], calibrations: Calibrations, backend: Optional[Backend] = None, cal_parameter_name: Optional[str] = "drive_freq", delay_duration: Optional[int] = None, repetitions: List[int] = None, auto_update: bool = True, gate_name: str = "sx", ): r"""See class :class:`.FineFrequency` for details. Note that this class implicitly assumes that the target angle of the gate is :math:`\pi/2` as seen from the default analysis options. This experiment can be seen as a calibration of a finite duration ``rz(pi/2)`` gate with any error attributed to a frequency offset in the qubit. Args: physical_qubits: Sequence containing the qubit for which to run the fine frequency calibration. calibrations: The calibrations instance with the schedules. backend: Optional, the backend to run the experiment on. cal_parameter_name: The name of the parameter to update in the calibrations. This defaults to `drive_freq`. delay_duration: The duration of the delay at :math:`n=1`. If this value is not given then the duration of the gate named ``gate_name`` in the calibrations will be used. auto_update: Whether to automatically update the calibrations or not. By default, this variable is set to True. gate_name: This argument is only needed if ``delay_duration`` is None. This should be the name of a valid schedule in the calibrations. """ if delay_duration is None: delay_duration = calibrations.get_schedule(gate_name, physical_qubits[0]).duration super().__init__( calibrations, physical_qubits, delay_duration=delay_duration, schedule_name=None, repetitions=repetitions, backend=backend, cal_parameter_name=cal_parameter_name, auto_update=auto_update, ) if self.backend is not None: self.set_experiment_options(dt=self._backend_data.dt) @classmethod def _default_experiment_options(cls): """default values for the fine frequency calibration experiment. Experiment Options: dt (float): The duration of the time unit ``dt`` of the delay and schedules in seconds. """ options = super()._default_experiment_options() options.dt = None return options def _metadata(self) -> Dict[str, any]: """Add metadata to the experiment data making it more self contained. The following keys are added to the experiment's metadata: cal_param_value: The value of the drive frequency parameter. This value together with the fit result will be used to find the new value of the drive frequency parameter. cal_param_name: The name of the parameter in the calibrations. cal_group: The calibration group to which the parameter belongs. delay_duration: The duration of the first delay. dt: The number of ``dt`` units of the delay. """ metadata = super()._metadata() metadata["delay_duration"] = self.experiment_options.delay_duration metadata["dt"] = self.experiment_options.dt metadata["cal_param_value"] = self._cals.get_parameter_value( self._param_name, self.physical_qubits, group=self.experiment_options.group, ) return metadata def _attach_calibrations(self, circuit: QuantumCircuit): """Adds the calibrations to the transpiled circuits.""" schedule = self._cals.get_schedule("sx", self.physical_qubits) circuit.add_calibration("sx", self.physical_qubits, schedule)
[docs] def update_calibrations(self, experiment_data: ExperimentData): r"""Update the qubit frequency based on the measured angle deviation. The frequency of the qubit is updated according to .. math:: f \to f - \frac{{\rm d}\theta}{2\pi\tau{\rm d}t} Here, :math:`{\rm d}\theta` is the measured angle error from the fit. The duration of the single qubit-gate is :math:`\tau` in samples and :math:`{\rm d}t` is the duration of a sample. This is also the duration of the time unit ``dt`` of the delay. """ result_index = self.experiment_options.result_index group = experiment_data.metadata["cal_group"] prev_freq = experiment_data.metadata["cal_param_value"] tau = experiment_data.metadata["delay_duration"] dt = experiment_data.metadata["dt"] d_theta = BaseUpdater.get_value(experiment_data, "d_theta", result_index) new_freq = prev_freq + d_theta / (2 * np.pi * tau * dt) BaseUpdater.add_parameter_value( self._cals, experiment_data, new_freq, self._param_name, self._sched_name, group )