See also

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

Ramsey Spectroscopy

The notebook will demonstrate Ramsey Spectroscopy, which is used to tune the \(|0\rangle \rightarrow |1\rangle\) drive frequency more precisely. Ramsey spectroscopy is also used to find \(T_2^*\).

import numpy as np
from qcodes.parameters import ManualParameter

from quantify_scheduler.gettables import ScheduleGettable
from quantify_scheduler.schedules.timedomain_schedules import ramsey_sched

import json

import rich  # noqa:F401

import quantify_core.data.handling as dh
from quantify_scheduler.device_under_test.quantum_device import QuantumDevice

from utils import initialize_hardware, run  # noqa:F401

Setup

In this section we configure the hardware configuration which specifies the connectivity of our system.

The experiments of this tutorial are meant to be executed with a Qblox Cluster controlling a transmon system. The experiments can also be executed using a dummy Qblox device that is created via an instance of the Cluster class, and is initialized with a dummy configuration. When using a dummy device, the analysis will not work because the experiments will return np.nan values.

Configuration file

This is a template hardware configuration file for a 2-qubit system with a flux-control line which can be used to tune the qubit frequency. We will only work with qubit 0.

The hardware connectivity is as follows, by cluster slot: - QCM (Slot 2) - \(\text{O}^{1}\): Flux line for q0. - \(\text{O}^{2}\): Flux line for q1. - QCM-RF (Slot 6) - \(\text{O}^{1}\): Drive line for q0 using fixed 80 MHz IF. - \(\text{O}^{2}\): Drive line for q1 using fixed 80 MHz IF. - QRM-RF (Slot 8) - \(\text{O}^{1}\) and \(\text{I}^{1}\): Shared readout line for q0/q1 using a fixed LO set at 7.5 GHz.

Note that in the hardware configuration below the mixers are uncorrected, but for high fidelity experiments this should also be done for all the modules.

with open("configs/tuning_transmon_coupled_pair_hardware_config.json") as hw_cfg_json_file:
    hardware_cfg = json.load(hw_cfg_json_file)

# Enter your own dataset directory here!
dh.set_datadir(dh.default_datadir())

Data will be saved in:
/root/quantify-data

Quantum device settings

Here we initialize our QuantumDevice and our qubit parameters, checkout this tutorial for further details.

In short, a QuantumDevice contains device elements where we save our found parameters. Here we are loading a template for 2 qubits, but we will only use qubit 0.

quantum_device = QuantumDevice.from_json_file("devices/transmon_device_2q.json")
qubit = quantum_device.get_element("q0")
quantum_device.hardware_config(hardware_cfg)
meas_ctrl, _, cluster = initialize_hardware(quantum_device, ip=None)

/usr/local/lib/python3.9/site-packages/quantify_scheduler/backends/types/qblox.py:1220: ValidationWarning: Setting `auto_lo_cal=on_lo_interm_freq_change` will overwrite settings `dc_offset_i=0.0` and `dc_offset_q=0.0`. To suppress this warning, do not set either `dc_offset_i` or `dc_offset_q` for this port-clock.
  warnings.warn(
/usr/local/lib/python3.9/site-packages/quantify_scheduler/backends/types/qblox.py:1235: ValidationWarning: Setting `auto_sideband_cal=on_interm_freq_change` will overwrite settings `amp_ratio=1.0` and `phase_error=0.0`. To suppress this warning, do not set either `amp_ratio` or `phase_error` for this port-clock.
  warnings.warn(

Ramsey oscillations

tau = ManualParameter(name="tau", unit="s", label="Time")
tau.batched = True

ramsey_sched_kwargs = {
    "qubit": qubit.name,
    "times": tau,
    "artificial_detuning": 0.0,
}

gettable = ScheduleGettable(
    quantum_device,
    schedule_function=ramsey_sched,
    schedule_kwargs=ramsey_sched_kwargs,
    real_imag=False,
    batched=True,
)
meas_ctrl.gettables(gettable)

tau_setpoints = np.arange(20e-9, 4e-6, 32e-9)

meas_ctrl.settables(tau)
meas_ctrl.setpoints(tau_setpoints)

quantum_device.cfg_sched_repetitions(500)
ramsey_ds = meas_ctrl.run("ramsey")
ramsey_ds

Starting batched measurement...
Iterative settable(s) [outer loop(s)]:
         --- (None) ---
Batched settable(s):
         tau
Batch size limit: 125

/usr/local/lib/python3.9/site-packages/quantify_scheduler/backends/qblox/compiler_abc.py:634: RuntimeWarning: Operation is interrupting previous Pulse because it starts before the previous ends, offending operation: Pulse "Rxy(90, 0, 'q0')" (t0=0.00010002000000000001, duration=4e-08)
  warnings.warn(

<xarray.Dataset> Size: 3kB
Dimensions:  (dim_0: 125)
Coordinates:
    x0       (dim_0) float64 1kB 2e-08 5.2e-08 8.4e-08 ... 3.956e-06 3.988e-06
Dimensions without coordinates: dim_0
Data variables:
    y0       (dim_0) float64 1kB nan nan nan nan nan nan ... nan nan nan nan nan
    y1       (dim_0) float64 1kB nan nan nan nan nan nan ... nan nan nan nan nan
Attributes:
    tuid:                             20241017-131143-196-14e37a
    name:                             ramsey
    grid_2d:                          False
    grid_2d_uniformly_spaced:         False
    1d_2_settables_uniformly_spaced:  False

xarray.Dataset

• Dimensions:
  • dim_0: 125
• Coordinates: (1)
  • x0
    (dim_0)
    float64
    2e-08 5.2e-08 ... 3.988e-06

    name :

    tau

    long_name :

    Time

    units :

    s

    batched :

    True

    array([2.000e-08, 5.200e-08, 8.400e-08, 1.160e-07, 1.480e-07, 1.800e-07,
           2.120e-07, 2.440e-07, 2.760e-07, 3.080e-07, 3.400e-07, 3.720e-07,
           4.040e-07, 4.360e-07, 4.680e-07, 5.000e-07, 5.320e-07, 5.640e-07,
           5.960e-07, 6.280e-07, 6.600e-07, 6.920e-07, 7.240e-07, 7.560e-07,
           7.880e-07, 8.200e-07, 8.520e-07, 8.840e-07, 9.160e-07, 9.480e-07,
           9.800e-07, 1.012e-06, 1.044e-06, 1.076e-06, 1.108e-06, 1.140e-06,
           1.172e-06, 1.204e-06, 1.236e-06, 1.268e-06, 1.300e-06, 1.332e-06,
           1.364e-06, 1.396e-06, 1.428e-06, 1.460e-06, 1.492e-06, 1.524e-06,
           1.556e-06, 1.588e-06, 1.620e-06, 1.652e-06, 1.684e-06, 1.716e-06,
           1.748e-06, 1.780e-06, 1.812e-06, 1.844e-06, 1.876e-06, 1.908e-06,
           1.940e-06, 1.972e-06, 2.004e-06, 2.036e-06, 2.068e-06, 2.100e-06,
           2.132e-06, 2.164e-06, 2.196e-06, 2.228e-06, 2.260e-06, 2.292e-06,
           2.324e-06, 2.356e-06, 2.388e-06, 2.420e-06, 2.452e-06, 2.484e-06,
           2.516e-06, 2.548e-06, 2.580e-06, 2.612e-06, 2.644e-06, 2.676e-06,
           2.708e-06, 2.740e-06, 2.772e-06, 2.804e-06, 2.836e-06, 2.868e-06,
           2.900e-06, 2.932e-06, 2.964e-06, 2.996e-06, 3.028e-06, 3.060e-06,
           3.092e-06, 3.124e-06, 3.156e-06, 3.188e-06, 3.220e-06, 3.252e-06,
           3.284e-06, 3.316e-06, 3.348e-06, 3.380e-06, 3.412e-06, 3.444e-06,
           3.476e-06, 3.508e-06, 3.540e-06, 3.572e-06, 3.604e-06, 3.636e-06,
           3.668e-06, 3.700e-06, 3.732e-06, 3.764e-06, 3.796e-06, 3.828e-06,
           3.860e-06, 3.892e-06, 3.924e-06, 3.956e-06, 3.988e-06])

• Data variables: (2)
  • y0
    (dim_0)
    float64
    nan nan nan nan ... nan nan nan nan

    name :

    magn

    long_name :

    Magnitude0

    units :

    V

    batched :

    True

    batch_size :

    1024

    array([nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan])

  • y1
    (dim_0)
    float64
    nan nan nan nan ... nan nan nan nan

    name :

    phase

    long_name :

    Phase0

    units :

    deg

    batched :

    True

    batch_size :

    1024

    array([nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,
           nan, nan, nan, nan, nan, nan, nan, nan])

• Indexes: (0)
• Attributes: (5)

  tuid :

  20241017-131143-196-14e37a

  name :

  ramsey

  grid_2d :

  False

  grid_2d_uniformly_spaced :

  False

  1d_2_settables_uniformly_spaced :

  False

qubit.clock_freqs.f01(qubit.clock_freqs.f01() + 100e3)

rich.print(quantum_device.hardware_config())

{
    'config_type': 'quantify_scheduler.backends.qblox_backend.QbloxHardwareCompilationConfig',
    'hardware_description': {
        'cluster0': {
            'instrument_type': 'Cluster',
            'modules': {
                '6': {'instrument_type': 'QCM_RF'},
                '2': {'instrument_type': 'QCM'},
                '8': {'instrument_type': 'QRM_RF'}
            },
            'sequence_to_file': False,
            'ref': 'internal'
        }
    },
    'hardware_options': {
        'output_att': {'q0:mw-q0.01': 10, 'q1:mw-q1.01': 10, 'q0:res-q0.ro': 60, 'q1:res-q1.ro': 60},
        'mixer_corrections': {
            'q0:mw-q0.01': {
                'auto_lo_cal': 'on_lo_interm_freq_change',
                'auto_sideband_cal': 'on_interm_freq_change',
                'dc_offset_i': None,
                'dc_offset_q': None,
                'amp_ratio': 1.0,
                'phase_error': 0.0
            },
            'q1:mw-q1.01': {
                'auto_lo_cal': 'on_lo_interm_freq_change',
                'auto_sideband_cal': 'on_interm_freq_change',
                'dc_offset_i': None,
                'dc_offset_q': None,
                'amp_ratio': 1.0,
                'phase_error': 0.0
            },
            'q0:res-q0.ro': {
                'auto_lo_cal': 'on_lo_interm_freq_change',
                'auto_sideband_cal': 'on_interm_freq_change',
                'dc_offset_i': None,
                'dc_offset_q': None,
                'amp_ratio': 1.0,
                'phase_error': 0.0
            },
            'q1:res-q1.ro': {
                'auto_lo_cal': 'on_lo_interm_freq_change',
                'auto_sideband_cal': 'on_interm_freq_change',
                'dc_offset_i': None,
                'dc_offset_q': None,
                'amp_ratio': 1.0,
                'phase_error': 0.0
            }
        },
        'modulation_frequencies': {
            'q0:mw-q0.01': {'interm_freq': 80000000.0},
            'q1:mw-q1.01': {'interm_freq': 80000000.0},
            'q0:res-q0.ro': {'lo_freq': 7500000000.0},
            'q1:res-q1.ro': {'lo_freq': 7500000000.0}
        }
    },
    'connectivity': {
        'graph': [
            ['cluster0.module6.complex_output_0', 'q0:mw'],
            ['cluster0.module6.complex_output_1', 'q1:mw'],
            ['cluster0.module2.real_output_0', 'q0:fl'],
            ['cluster0.module2.real_output_1', 'q1:fl'],
            ['cluster0.module8.complex_output_0', 'q0:res'],
            ['cluster0.module8.complex_output_0', 'q1:res']
        ]
    }
}

quantum_device.to_json_file("devices/")

'devices/device_2q_2024-10-17_13-11-43_UTC.json'