Calibrating Signals

When executing experiments on qubits, you will typically need to first determine the parameters of your quantum devices through a set of calibration experiments. Examples of calibration values are resonator and qubit transition frequencies or signal delays due to differing cable lengths or properties. Subsequent experiments can then reuse the previously determined, calibrated values.

To support this workflow, LabOne Q introduces calibration objects associated with device setups or experiments.

In this chapter, we introduce the concepts underlying the execution of experiments with calibrated parameter values within LabOne Q. For an in-depth and hands-on overview of the concepts, we also recommend having a look at the calibration reference example notebook.

The Calibration Object

All of the calibration values relevant to run an experiment from LabOne Q are part of a Calibration object. This object contains a dictionary where the keys reference signals or channels that have calibration values associated with them, and the values are SignalCalibration objects. The actual calibration values defined on signal lines are then defined as properties of the SignalCalibration, and can be accessed and set through it.

There are two types of calibration: baseline and experimental calibration. The baseline calibration is defined as a property of the device setup, while the experimental calibration is defined as part of an experiment. For an illustrative example of how to utilize both baseline and experimental calibration to tune-up a single qubit, have a look at the single qubit tuneup example notebook.

In this chapter, we will focus on the baseline calibration. For an overview and explanation of the experimental calibration, see the chapter on Experiment Calibration.

Baseline Calibration

The baseline calibration is defined on the device setup and is associated with logical signals and, through them, directly with connected quantum devices. It serves as the primary repository of instrument settings and values relevant to executing an experiment on these quantum devices. Typically, the baseline calibration will be set once, after the tune-up of a chip is complete, and only modified if recalibration is necessary.

This is in contrast to the experiment calibration, which may be set differently for each experiment, but which does not influence the baseline calibration settings.

Accessing the baseline calibration from the device setup is done through

my_base_calibration = my_device_setup.get_calibration()

Logical Signal Lines

Any logical signal defined on the device setup automatically has a SignalCalibration attached to it at the creation of the DeviceSetup object. Initially, all properties of this calibration will be set to None, as no calibration data has yet been specified.

The calibration properties of logical signals are listed in the table below, sorted by instrument and signal type.

Table 1: Logical signal calibration properties by instrument and signal type

Instrument	channel type	supported properties
HDAWG	iq_channel	oscillator delay_signal
HDAWG	rf_channel	oscillator delay_signal
UHFQA	iq_channel	oscillator delay_signal threshold (input channels only)
SHFQA	iq_channel	oscillator delay_signal threshold (input channels only)
SHFSG	iq_channel	oscillator delay_signal

Advanced Topic: Physical Channels

Some of the calibration properties of a logical signal line may refer to actual instrument settings which will be shared between any logical signals sharing the same physical output of an instrument.

Note

It is possible to set any physical channel property on any of the assigned logical signals. However, through the mechanism of the physical channels, the proper value is distributed automatically to all attached logical signals.

Valid calibrations of physical channels for the different instruments are detailed in the table below.

Table 2: Physical channel calibration properties by instrument and channel type

Instrument	channel type	supported properties
HDAWG	iq_channel	mixer_calibration port_delay
HDAWG	rf_channel	port_delay
UHFQA	iq_channel	port_delay (input channels only)
SHFQA	iq_channel	port_delay local_oscillator range
SHFSG	iq_channel	port_delay local_oscillator range port_mode