Source code for qiskit_experiments.library.characterization.t2ramsey
# 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.## 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."""T2Ramsey Experiment class."""fromtypingimportList,Union,Optional,SequenceimportnumpyasnpimportqiskitfromqiskitimportQuantumCircuitfromqiskit.providers.backendimportBackendfromqiskit_experiments.frameworkimportBackendTiming,BaseExperiment,Optionsfromqiskit_experiments.library.characterization.analysis.t2ramsey_analysisimportT2RamseyAnalysis
[docs]classT2Ramsey(BaseExperiment):r"""An experiment to measure the Ramsey frequency and the qubit dephasing time sensitive to inhomogeneous broadening. # section: overview This experiment is used to estimate two properties for a single qubit: :math:`T_2^*` and Ramsey frequency. :math:`T_2^*` is the dephasing time or the transverse relaxation time of the qubit on the Bloch sphere as a result of both energy relaxation and pure dephasing in the transverse plane. Unlike :math:`T_2`, which is measured by :class:`.T2Hahn`, :math:`T_2^*` is sensitive to inhomogenous broadening. This experiment consists of a series of circuits of the form .. parsed-literal:: ┌───┐┌──────────────┐┌──────┐ ░ ┌───┐ ░ ┌─┐ q_0: ┤ H ├┤ DELAY(t) ├┤ P(λ) ├─░─┤ H ├─░─┤M├ └───┘└──────────────┘└──────┘ ░ └───┘ ░ └╥┘ c: 1/═════════════════════════════════════════╩═ 0 for each *t* from the specified delay times, where :math:`\lambda =2 \pi \times {osc\_freq}`, and the delays are specified by the user. The circuits are run on the device or on a simulator backend. # section: manual :doc:`/manuals/characterization/t2ramsey` # section: analysis_ref :class:`T2RamseyAnalysis` # section: example .. jupyter-execute:: :hide-code: # Temporary workaround for missing support in Qiskit and qiskit-ibm-runtime from qiskit_experiments.test.patching import patch_sampler_test_support patch_sampler_test_support() # backend from qiskit_ibm_runtime.fake_provider import FakeManilaV2 from qiskit_aer import AerSimulator from qiskit_aer.noise import NoiseModel noise_model = NoiseModel.from_backend(FakeManilaV2(), thermal_relaxation=True, gate_error=False, readout_error=False, ) backend = AerSimulator.from_backend(FakeManilaV2(), noise_model=noise_model) .. jupyter-execute:: import numpy as np import qiskit from qiskit_experiments.library import T2Ramsey delays = list(np.arange(1.00e-6, 50.0e-6, 2.00e-6)) exp = T2Ramsey(physical_qubits=(0, ), delays=delays, backend=backend, osc_freq=1.0e5) exp_data = exp.run().block_for_results() display(exp_data.figure(0)) exp_data.analysis_results(dataframe=True) # section: reference .. ref_arxiv:: 1 1904.06560 """@classmethoddef_default_experiment_options(cls)->Options:"""Default experiment options. Experiment Options: delays (Iterable[float]): Delay times of the experiments in seconds. osc_freq (float): Oscillation frequency offset in Hz. """options=super()._default_experiment_options()options.delays=Noneoptions.osc_freq=0.0returnoptionsdef__init__(self,physical_qubits:Sequence[int],delays:Union[List[float],np.array],backend:Optional[Backend]=None,osc_freq:float=0.0,):""" Initialize the T2Ramsey class. Args: physical_qubits: a single-element sequence containing the qubit under test. delays: delay times of the experiments in seconds. backend: Optional, the backend to run the experiment on. osc_freq: the oscillation frequency induced by the user. The frequency is given in Hz. """super().__init__(physical_qubits,analysis=T2RamseyAnalysis(),backend=backend)self.set_experiment_options(delays=delays,osc_freq=osc_freq)
[docs]defcircuits(self)->List[QuantumCircuit]:"""Return a list of experiment circuits. Each circuit consists of a Hadamard gate, followed by a fixed delay, a phase gate (with a linear phase), and an additional Hadamard gate. Returns: The experiment circuits """timing=BackendTiming(self.backend)circuits=[]fordelayinself.experiment_options.delays:rotation_angle=(2*np.pi*self.experiment_options.osc_freq*timing.delay_time(time=delay))circ=qiskit.QuantumCircuit(1,1)circ.sx(0)# Brings the qubit to the X Axiscirc.delay(timing.round_delay(time=delay),0,timing.delay_unit)circ.rz(rotation_angle,0)circ.barrier(0)circ.sx(0)circ.barrier(0)circ.measure(0,0)circ.metadata={"xval":timing.delay_time(time=delay)}circuits.append(circ)returncircuits
def_metadata(self):metadata=super()._metadata()# Store measurement level and meas return if they have been# set for the experimentforrun_optin["meas_level","meas_return"]:ifhasattr(self.run_options,run_opt):metadata[run_opt]=getattr(self.run_options,run_opt)metadata["osc_freq"]=self.experiment_options.osc_freqreturnmetadata