Source code for qibocal.protocols.flux_dependence.qubit_flux_dependence

from dataclasses import dataclass, field
from typing import Optional

import numpy as np
import numpy.typing as npt
from qibolab import AcquisitionType, AveragingMode, ExecutionParameters
from qibolab.platform import Platform
from qibolab.pulses import PulseSequence
from qibolab.qubits import QubitId
from qibolab.sweeper import Parameter, Sweeper, SweeperType
from scipy.optimize import curve_fit

from qibocal import update
from qibocal.auto.operation import Data, Results, Routine
from qibocal.config import log
from qibocal.protocols.qubit_spectroscopy_ef import DEFAULT_ANHARMONICITY

from ..utils import GHZ_TO_HZ, HZ_TO_GHZ, extract_feature, table_dict, table_html
from . import utils
from .resonator_flux_dependence import ResonatorFluxParameters


[docs]@dataclass class QubitFluxParameters(ResonatorFluxParameters): """QubitFlux runcard inputs.""" drive_amplitude: Optional[float] = None """Drive amplitude (optional). If defined, same amplitude will be used in all qubits. Otherwise the default amplitude defined on the platform runcard will be used""" transition: Optional[str] = "01" """Flux spectroscopy transition type ("01" or "02"). Default value is 01""" drive_duration: int = 2000 """Duration of the drive pulse."""
[docs]@dataclass class QubitFluxResults(Results): """QubitFlux outputs.""" sweetspot: dict[QubitId, float] """Sweetspot for each qubit.""" frequency: dict[QubitId, float] """Drive frequency for each qubit.""" fitted_parameters: dict[QubitId, dict[str, float]] """Raw fitting output.""" matrix_element: dict[QubitId, float] """V_ii coefficient."""
QubitFluxType = np.dtype( [ ("freq", np.float64), ("bias", np.float64), ("signal", np.float64), ("phase", np.float64), ] ) """Custom dtype for resonator flux dependence."""
[docs]@dataclass class QubitFluxData(Data): """QubitFlux acquisition outputs.""" resonator_type: str """Resonator type.""" charging_energy: dict[QubitId, float] = field(default_factory=dict) """Qubit charging energy.""" qubit_frequency: dict[QubitId, float] = field(default_factory=dict) """Qubit charging energy.""" data: dict[QubitId, npt.NDArray[QubitFluxType]] = field(default_factory=dict) """Raw data acquired."""
[docs] def register_qubit(self, qubit, freq, bias, signal, phase): """Store output for single qubit.""" self.data[qubit] = utils.create_data_array( freq, bias, signal, phase, dtype=QubitFluxType )
[docs]def _acquisition( params: QubitFluxParameters, platform: Platform, targets: list[QubitId], ) -> QubitFluxData: """Data acquisition for QubitFlux Experiment.""" # taking advantage of multiplexing, apply the same set of gates to all qubits in parallel sequence = PulseSequence() ro_pulses = {} qd_pulses = {} qubit_frequency = {} for qubit in targets: qd_pulses[qubit] = platform.create_qubit_drive_pulse( qubit, start=0, duration=params.drive_duration ) qubit_frequency[qubit] = platform.qubits[qubit].drive_frequency if params.transition == "02": if platform.qubits[qubit].anharmonicity: qd_pulses[qubit].frequency -= platform.qubits[qubit].anharmonicity / 2 else: qd_pulses[qubit].frequency -= DEFAULT_ANHARMONICITY / 2 if params.drive_amplitude is not None: qd_pulses[qubit].amplitude = params.drive_amplitude ro_pulses[qubit] = platform.create_qubit_readout_pulse( qubit, start=qd_pulses[qubit].finish ) sequence.add(qd_pulses[qubit]) sequence.add(ro_pulses[qubit]) # define the parameters to sweep and their range: delta_frequency_range = np.arange( -params.freq_width / 2, params.freq_width / 2, params.freq_step ) freq_sweeper = Sweeper( Parameter.frequency, delta_frequency_range, pulses=[qd_pulses[qubit] for qubit in targets], type=SweeperType.OFFSET, ) delta_bias_range = np.arange( -params.bias_width / 2, params.bias_width / 2, params.bias_step ) sweepers = [ Sweeper( Parameter.bias, delta_bias_range, qubits=[platform.qubits[qubit] for qubit in targets], type=SweeperType.OFFSET, ) ] data = QubitFluxData( resonator_type=platform.resonator_type, charging_energy={ qubit: -platform.qubits[qubit].anharmonicity for qubit in targets }, qubit_frequency=qubit_frequency, ) options = ExecutionParameters( nshots=params.nshots, relaxation_time=params.relaxation_time, acquisition_type=AcquisitionType.INTEGRATION, averaging_mode=AveragingMode.CYCLIC, ) for bias_sweeper in sweepers: results = platform.sweep(sequence, options, bias_sweeper, freq_sweeper) # retrieve the results for every qubit for qubit in targets: result = results[ro_pulses[qubit].serial] sweetspot = platform.qubits[qubit].sweetspot data.register_qubit( qubit, signal=result.magnitude, phase=result.phase, freq=delta_frequency_range + qd_pulses[qubit].frequency, bias=delta_bias_range + sweetspot, ) return data
[docs]def _fit(data: QubitFluxData) -> QubitFluxResults: """ Post-processing for QubitFlux Experiment. See arxiv:0703002 Fit frequency as a function of current for the flux qubit spectroscopy data (QubitFluxData): data object with information on the feature response at each current point. """ qubits = data.qubits frequency = {} sweetspot = {} matrix_element = {} fitted_parameters = {} for qubit in qubits: qubit_data = data[qubit] biases = qubit_data.bias frequencies = qubit_data.freq signal = qubit_data.signal frequencies, biases = extract_feature( frequencies, biases, signal, "max" if data.resonator_type == "2D" else "min" ) def fit_function(x, w_max, normalization, offset): return utils.transmon_frequency( xi=x, w_max=w_max, xj=0, d=0, normalization=normalization, offset=offset, crosstalk_element=1, charging_energy=data.charging_energy[qubit] * HZ_TO_GHZ, ) try: popt = curve_fit( fit_function, biases, frequencies * HZ_TO_GHZ, bounds=utils.qubit_flux_dependence_fit_bounds( data.qubit_frequency[qubit], ), maxfev=100000, )[0] fitted_parameters[qubit] = { "w_max": popt[0], "xj": 0, "d": 0, "normalization": popt[1], "offset": popt[2], "crosstalk_element": 1, "charging_energy": data.charging_energy[qubit] * HZ_TO_GHZ, } frequency[qubit] = popt[0] * GHZ_TO_HZ # solution to x*popt[1] + popt[2] = k # such that x is close to 0 # to avoid errors due to periodicity sweetspot[qubit] = (np.round(popt[2]) - popt[2]) / popt[1] matrix_element[qubit] = popt[1] except ValueError as e: log.error( f"Error in qubit_flux protocol fit: {e} " "The threshold for the SNR mask is probably too high. " "Lowering the value of `threshold` in `extract_*_feature`" "should fix the problem." ) return QubitFluxResults( frequency=frequency, sweetspot=sweetspot, matrix_element=matrix_element, fitted_parameters=fitted_parameters, )
[docs]def _plot(data: QubitFluxData, fit: QubitFluxResults, target: QubitId): """Plotting function for QubitFlux Experiment.""" figures = utils.flux_dependence_plot( data, fit, target, fit_function=utils.transmon_frequency, ) if fit is not None: fitting_report = table_html( table_dict( target, [ f"Sweetspot [V]", "Qubit Frequency at Sweetspot [Hz]", "Flux dependence [V]^-1", ], [ np.round(fit.sweetspot[target], 4), np.round(fit.frequency[target], 4), np.round(fit.matrix_element[target], 4), ], ) ) return figures, fitting_report return figures, ""
[docs]def _update(results: QubitFluxResults, platform: Platform, qubit: QubitId): update.drive_frequency(results.frequency[qubit], platform, qubit) update.sweetspot(results.sweetspot[qubit], platform, qubit) update.crosstalk_matrix(results.matrix_element[qubit], platform, qubit, qubit)
qubit_flux = Routine(_acquisition, _fit, _plot, _update) """QubitFlux Routine object."""