Drag

class Drag(duration, amp, sigma, beta, name=None, limit_amplitude=None)

Bases: qiskit.pulse.library.parametric_pulses.ParametricPulse

The Derivative Removal by Adiabatic Gate (DRAG) pulse is a standard Gaussian pulse with an additional Gaussian derivative component and lifting applied.

It is designed to reduce the frequency spectrum of a normal gaussian pulse near the $|1\rangle\leftrightarrow|2\rangle$ transition, reducing the chance of leakage to the $|2\rangle$ state.

\begin{split}g(x) &= \exp\Bigl(-\frac12 \frac{(x - \text{duration}/2)^2}{\text{sigma}^2}\Bigr)\\ f'(x) &= g(x) + 1j \times \text{beta} \times \frac{\mathrm d}{\mathrm{d}x} g(x)\\ &= g(x) + 1j \times \text{beta} \times \Bigl(-\frac{x - \text{duration}/2}{\text{sigma}^2}\Bigr)g(x)\\ f(x) &= \text{amp}\times\frac{f'(x)-f'(-1)}{1-f'(-1)}, \quad 0 \le x < \text{duration}\end{split}

where $g(x)$ is a standard unlifted gaussian waveform and $f'(x)$ is the DRAG waveform without lifting or amplitude scaling.

This pulse would be more accurately named as LiftedDrag, however, for historical and practical DSP reasons it has the name Drag.

References

Initialize the drag pulse.

Parameters

duration (Union[int, ParameterExpression]) – Pulse length in terms of the the sampling period dt.
amp (Union[complex, ParameterExpression]) – The amplitude of the Drag envelope.
sigma (Union[float, ParameterExpression]) – A measure of how wide or narrow the Gaussian peak is; described mathematically in the class docstring.
beta (Union[float, ParameterExpression]) – The correction amplitude.
name (Optional[str]) – Display name for this pulse envelope.
limit_amplitude (Optional[bool]) – If True, then limit the amplitude of the waveform to 1. The default is True and the amplitude is constrained to 1.

Methods

draw

Drag.draw(style=None, backend=None, time_range=None, time_unit='dt', show_waveform_info=True, plotter='mpl2d', axis=None)

Plot the interpolated envelope of pulse.

Parameters

style (Optional[Dict[str, Any]]) – Stylesheet options. This can be dictionary or preset stylesheet classes. See IQXStandard, IQXSimple, and IQXDebugging for details of preset stylesheets.
backend (Optional[BaseBackend]) – Backend object to play the input pulse program. If provided, the plotter may use to make the visualization hardware aware.
time_range (Optional[Tuple[int, int]]) – Set horizontal axis limit. Tuple (tmin, tmax).
time_unit (str) – The unit of specified time range either dt or ns. The unit of ns is available only when backend object is provided.
show_waveform_info (bool) – Show waveform annotations, i.e. name, of waveforms. Set True to show additional information about waveforms.

plotter (str) –

Name of plotter API to generate an output image. One of following APIs should be specified:

mpl2d: Matplotlib API for 2D image generation.
    Matplotlib API to generate 2D image. Charts are placed along y axis with
    vertical offset. This API takes matplotlib.axes.Axes as `axis` input.

axis and style kwargs may depend on the plotter.

axis (Optional[Any]) – Arbitrary object passed to the plotter. If this object is provided, the plotters use a given axis instead of internally initializing a figure object. This object format depends on the plotter. See plotter argument for details.

Returns

Visualization output data. The returned data type depends on the plotter. If matplotlib family is specified, this will be a matplotlib.pyplot.Figure data.

get_waveform

Drag.get_waveform()

Return a Waveform with samples filled according to the formula that the pulse represents and the parameter values it contains.

Return type

Waveform

is_parameterized

Drag.is_parameterized()

Return True iff the instruction is parameterized.

Return type

bool

validate_parameters

Drag.validate_parameters()

Validate parameters.

Raises

PulseError – If the parameters passed are not valid.

Return type

None

Attributes

amp

The Gaussian amplitude.

Return type

Union[complex, ParameterExpression]

beta

The weighing factor for the Gaussian derivative component of the waveform.

Return type

Union[float, ParameterExpression]

id

Unique identifier for this pulse.

Return type

int

limit_amplitude

Default value: True

parameters

Return type

Dict[str, Any]

sigma

The Gaussian standard deviation of the pulse width.

Return type

Union[float, ParameterExpression]

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