Flux-dependent qubit spectroscopy Experiment¶

This notebook demonstrates how to perform qubit spectroscopy if the qubit resonance frequnecy depends on a second parameter, e.g. an external flux. We perform a 2D sweep of the amplitude of the applied external flux and the frequency of an excitation tone applied to the qubit itself.

0. General Imports and Definitions¶

0.1 Python Imports¶

In [ ]:

# Helpers:
from laboneq.contrib.example_helpers.generate_device_setup import (
    generate_device_setup_qubits,
)
from laboneq.contrib.example_helpers.plotting.plot_helpers import *

# LabOne Q:
from laboneq.simple import *

# Helpers: from laboneq.contrib.example_helpers.generate_device_setup import ( generate_device_setup_qubits, ) from laboneq.contrib.example_helpers.plotting.plot_helpers import * # LabOne Q: from laboneq.simple import *

1. Device Setup¶

Below, you'll create a device setup and choose to run this notebook in emulated mode or directly on the control hardware, by specifying use_emulation = True/False respectively.

If you run on your hardware, you need to generate a device setup first, please have a look at our device setup tutorial for how to do this in general. Here, we use a helper functions to generate the device setup and a set up qubit objects with pre-defined parameters.

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# specify the number of qubits you want to use
number_of_qubits = 2

# generate the device setup and the qubit objects using a helper function
device_setup, qubits = generate_device_setup_qubits(
    number_qubits=number_of_qubits,
    pqsc=[{"serial": "DEV10001"}],
    hdawg=[
        {
            "serial": "DEV8001",
            "number_of_channels": 8,
            "options": None,
        }
    ],
    shfqc=[
        {
            "serial": "DEV12001",
            "number_of_channels": 6,
            "readout_multiplex": 6,
            "options": None,
        }
    ],
    multiplex_drive_lines=True,
    include_flux_lines=True,
    server_host="localhost",
    setup_name=f"my_{number_of_qubits}_tunable_qubit_setup",
)

q0, q1 = qubits[:2]

# specify the number of qubits you want to use number_of_qubits = 2 # generate the device setup and the qubit objects using a helper function device_setup, qubits = generate_device_setup_qubits( number_qubits=number_of_qubits, pqsc=[{"serial": "DEV10001"}], hdawg=[ { "serial": "DEV8001", "number_of_channels": 8, "options": None, } ], shfqc=[ { "serial": "DEV12001", "number_of_channels": 6, "readout_multiplex": 6, "options": None, } ], multiplex_drive_lines=True, include_flux_lines=True, server_host="localhost", setup_name=f"my_{number_of_qubits}_tunable_qubit_setup", ) q0, q1 = qubits[:2]

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# use emulation mode - no connection to instruments
use_emulation = True

# create and connect to a session
session = Session(device_setup=device_setup)
session.connect(do_emulation=use_emulation)

# use emulation mode - no connection to instruments use_emulation = True # create and connect to a session session = Session(device_setup=device_setup) session.connect(do_emulation=use_emulation)

2. Experiment Definition¶

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#  signal map for qubit
def map_qubit(qubit):
    return {
        "drive": qubit.signals["drive"],
        "flux": qubit.signals["flux"],
        "measure": qubit.signals["measure"],
        "acquire": qubit.signals["acquire"],
    }

# signal map for qubit def map_qubit(qubit): return { "drive": qubit.signals["drive"], "flux": qubit.signals["flux"], "measure": qubit.signals["measure"], "acquire": qubit.signals["acquire"], }

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## define pulses
# flux pulse - applied during whole experimental pulse sequence
const_flux = pulse_library.const(uid="const_flux", length=600e-9, amplitude=1.0)
# qubit drive pulse
const_iq_100ns = pulse_library.const(uid="const_iq_100ns", length=100e-9, amplitude=1.0)
# readout drive pulse
readout_pulse = pulse_library.const(uid="readout_pulse", length=400e-9, amplitude=1.0)
# readout weights for integration
readout_weighting_function = pulse_library.const(
    uid="readout_weighting_function", length=400e-9, amplitude=1.0
)

## define pulses # flux pulse - applied during whole experimental pulse sequence const_flux = pulse_library.const(uid="const_flux", length=600e-9, amplitude=1.0) # qubit drive pulse const_iq_100ns = pulse_library.const(uid="const_iq_100ns", length=100e-9, amplitude=1.0) # readout drive pulse readout_pulse = pulse_library.const(uid="readout_pulse", length=400e-9, amplitude=1.0) # readout weights for integration readout_weighting_function = pulse_library.const( uid="readout_weighting_function", length=400e-9, amplitude=1.0 )

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# define sweep parameter - sweep over the frequency of a qubit excitation pulse
start = 40e6
stop = 200e6
count = 11

freq_sweep = LinearSweepParameter(
    uid="qubit_frequency", start=start, stop=stop, count=count
)

# Second sweep: Amplitude of the flux pulsed
flux_count = 21

flux_sweep = LinearSweepParameter(uid="flux_qubit", start=0, stop=1, count=flux_count)

# define number of averages
average_exponent = 4  # used for 2^n averages, n=average_exponent, maximum: n = 17

# define sweep parameter - sweep over the frequency of a qubit excitation pulse start = 40e6 stop = 200e6 count = 11 freq_sweep = LinearSweepParameter( uid="qubit_frequency", start=start, stop=stop, count=count ) # Second sweep: Amplitude of the flux pulsed flux_count = 21 flux_sweep = LinearSweepParameter(uid="flux_qubit", start=0, stop=1, count=flux_count) # define number of averages average_exponent = 4 # used for 2^n averages, n=average_exponent, maximum: n = 17

2.1 Pulse Sequence¶

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# Create Experiment - no explicit mapping to qubit lines
exp = Experiment(
    uid="Qubit Flux Spectroscopy",
    signals=[
        ExperimentSignal("flux"),
        ExperimentSignal("drive"),
        ExperimentSignal("measure"),
        ExperimentSignal("acquire"),
    ],
)
## experimental pulse sequence
with exp.acquire_loop_rt(
    uid="shots",
    count=pow(2, average_exponent),
    averaging_mode=AveragingMode.CYCLIC,
    acquisition_type=AcquisitionType.INTEGRATION,
):
    with exp.sweep(uid="sweep", parameter=freq_sweep):
        # inner loop - real-time, sequential averaging in standard integration mode
        # inner loop - adjust flux bias to qubit
        with exp.sweep(uid="flux_sweep", parameter=flux_sweep):
            with exp.section(uid="flux bias"):
                exp.play(signal="flux", pulse=const_flux, amplitude=flux_sweep)
            # qubit excitation pulse - frequency will be swept
            with exp.section(uid="qubit_excitation"):
                # allow for transients to settle
                exp.delay(signal="drive", time=100e-9)
                # play excitation pulse
                exp.play(signal="drive", pulse=const_iq_100ns)
            # readout and data acquisition
            with exp.section(uid="qubit_readout", play_after="qubit_excitation"):
                # play readout pulse
                exp.play(signal="measure", pulse=readout_pulse)
                # signal data acquisition
                exp.acquire(
                    signal="acquire",
                    handle="ac_0",
                    kernel=readout_weighting_function,
                )
            # relax time after readout - for signal processing and qubit relaxation to ground state
            with exp.section(uid="relax", play_after="qubit_readout"):
                exp.delay(signal="measure", time=1e-6)

# Create Experiment - no explicit mapping to qubit lines exp = Experiment( uid="Qubit Flux Spectroscopy", signals=[ ExperimentSignal("flux"), ExperimentSignal("drive"), ExperimentSignal("measure"), ExperimentSignal("acquire"), ], ) ## experimental pulse sequence with exp.acquire_loop_rt( uid="shots", count=pow(2, average_exponent), averaging_mode=AveragingMode.CYCLIC, acquisition_type=AcquisitionType.INTEGRATION, ): with exp.sweep(uid="sweep", parameter=freq_sweep): # inner loop - real-time, sequential averaging in standard integration mode # inner loop - adjust flux bias to qubit with exp.sweep(uid="flux_sweep", parameter=flux_sweep): with exp.section(uid="flux bias"): exp.play(signal="flux", pulse=const_flux, amplitude=flux_sweep) # qubit excitation pulse - frequency will be swept with exp.section(uid="qubit_excitation"): # allow for transients to settle exp.delay(signal="drive", time=100e-9) # play excitation pulse exp.play(signal="drive", pulse=const_iq_100ns) # readout and data acquisition with exp.section(uid="qubit_readout", play_after="qubit_excitation"): # play readout pulse exp.play(signal="measure", pulse=readout_pulse) # signal data acquisition exp.acquire( signal="acquire", handle="ac_0", kernel=readout_weighting_function, ) # relax time after readout - for signal processing and qubit relaxation to ground state with exp.section(uid="relax", play_after="qubit_readout"): exp.delay(signal="measure", time=1e-6)

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# define experiment calibration - sweep over qubit drive frequency
exp_calib = Calibration()
exp_calib["drive"] = SignalCalibration(
    oscillator=Oscillator(
        frequency=freq_sweep,
        modulation_type=ModulationType.HARDWARE,
    )
)

# define experiment calibration - sweep over qubit drive frequency exp_calib = Calibration() exp_calib["drive"] = SignalCalibration( oscillator=Oscillator( frequency=freq_sweep, modulation_type=ModulationType.HARDWARE, ) )

2.2 Run the Experiment and Plot the Measurement Results and Pulse Sequence¶

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# set calibration and signal map for qubit 0
exp.set_calibration(exp_calib)
exp.set_signal_map(map_qubit(q0))

# run experiment on qubit 0
my_results = session.run(exp)

# set calibration and signal map for qubit 0 exp.set_calibration(exp_calib) exp.set_signal_map(map_qubit(q0)) # run experiment on qubit 0 my_results = session.run(exp)

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# Plot simulated output signals
plot_simulation(session.compiled_experiment, start_time=0, length=10e-6)

# Plot simulated output signals plot_simulation(session.compiled_experiment, start_time=0, length=10e-6)

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# plot measurement results
plot_result_3d(my_results, "ac_0")

# plot measurement results plot_result_3d(my_results, "ac_0")

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# use pulse sheet viewer to display the pulse sequence - only recommended for small number of averages and sweep steps to avoid performance issues
show_pulse_sheet("Qubit Flux Spectroscopy", session.compiled_experiment)

# use pulse sheet viewer to display the pulse sequence - only recommended for small number of averages and sweep steps to avoid performance issues show_pulse_sheet("Qubit Flux Spectroscopy", session.compiled_experiment)

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# set calibration and signal map for qubit 1
exp.set_calibration(exp_calib)
exp.set_signal_map(map_qubit(q1))

# run experiment on qubit 1
my_results = session.run(exp)

# set calibration and signal map for qubit 1 exp.set_calibration(exp_calib) exp.set_signal_map(map_qubit(q1)) # run experiment on qubit 1 my_results = session.run(exp)

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