See also

A Jupyter notebook version of this tutorial can be downloaded here.

Rabi

After determining the qubit’s |0⟩ → |1⟩ transition frequency, a Rabi experiment is performed to calibrate the required microwave drive amplitude. The frequency and duration of the pulse are kept constant while the amplitude is swept, leading to oscillations in the qubit state. The power level that first fully inverts the qubit’s population (a π-pulse) is then identified.

from dependencies.analysis_utils import RabiAnalysis
from xarray import open_dataset

from qblox_scheduler import HardwareAgent, Schedule
from qblox_scheduler.experiments import SetHardwareOption
from qblox_scheduler.operations import Measure, Reset, X
from qblox_scheduler.operations.expressions import DType
from qblox_scheduler.operations.loop_domains import arange, linspace

Generating hash table for SingleQubitClifford.
Hash table generated.
Generating hash table for TwoQubitCliffordCZ.
Hash table generated.
Generating hash table for TwoQubitCliffordZX.
Hash table generated.
Testing decompositions.
Test passed.

Setup

The hardware agent manages the connection to the instrument and ensures that pulses and acquisitions happen over the appropriate input and output channels of the Cluster. The cell below creates an instance of the HardwareAgent based on the hardware- and device-under-test configuration files in the ./dependencies/configs folder, allowing us to start doing measurements. We also define some convenient aliases to use throughout our measurements. For a more thorough discussion of the hardware- and device-under-test configuration files, check out this tutorial.

# Set up hardware agent, this automatically connects to the instrument
hw_agent = HardwareAgent(
    hardware_configuration="./dependencies/configs/hw_config.json",
    quantum_device_configuration="./dependencies/configs/dut_config.json",
)

# convenience aliases
q0 = hw_agent.quantum_device.get_element("q0")
q2 = hw_agent.quantum_device.get_element("q2")
cluster = hw_agent.get_clusters()["cluster"]
hw_options = hw_agent.hardware_configuration.hardware_options
qubit = q0

/builds/0/.venv/lib/python3.10/site-packages/qblox_scheduler/qblox/hardware_agent.py:460: UserWarning: cluster: Trying to instantiate cluster with ip 'None'.Creating a dummy cluster.
  warnings.warn(

Experiment settings

# Drive attenuation settings. Should be an even number <= 30
drive_att = 12  # dB

# Rabi settings
amp_start = -0.5  # a.u.
amp_stop = 0.5  # a.u.
amp_npoints = 100

repetitions = 1000

Experiment schedule

rabi_power_sched = Schedule("power_rabi")
rabi_power_sched.add(SetHardwareOption("output_att", drive_att, f"{qubit.name}:mw-{qubit.name}.01"))

with (
    rabi_power_sched.loop(arange(0, repetitions, 1, DType.NUMBER)),
    rabi_power_sched.loop(
        linspace(start=amp_start, stop=amp_stop, num=amp_npoints, dtype=DType.AMPLITUDE)
    ) as amp,
):
    rabi_power_sched.add(Reset(qubit.name))
    # Play pulse of varying amplitude
    rabi_power_sched.add(X(qubit=qubit.name, amp180=amp))
    rabi_power_sched.add(Measure(qubit.name, coords={"amplitude": amp}, acq_channel="S_21"))

# Execute the experiment
rabi_data = hw_agent.run(rabi_power_sched)
if cluster.is_dummy:
    example_data = open_dataset("./dependencies/datasets/rabi.hdf5", engine="h5netcdf")
    rabi_data = rabi_data.update({"S_21": example_data.S_21})

Analyze the experiment

rabi_analysis = RabiAnalysis(rabi_data).run()
rabi_analysis.display_figs_mpl()

Post-run

# Update device config
qubit.rxy.amp180 = rabi_analysis.quantities_of_interest["Pi-pulse amplitude"].nominal_value

Update the device configuration file

After measurement, we may store the measured device properties inside a new file to use in future experiments. The time-unique identifier ensures that it is easy to find back previously found measurement results.

hw_agent.quantum_device.to_json_file("./dependencies/configs", add_timestamp=True)

'./dependencies/configs/two_flux_tunable_transmons_2025-10-30_00-37-32_UTC.json'