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# qiskit.pulse.library.Cos¶

Cos(duration, amp, phase, freq=None, angle=0.0, name=None, limit_amplitude=None)[source]

A cosine pulse.

The envelope of the pulse is given by:

$f(x) &= \text{A}\cos\left(2\pi ext{freq}x+\text{phase}\right) , 0 <= x < duration$

where $$\text{A} = \text{amp} \times\exp\left(i\times\text{angle}\right)$$.

Parameters
• duration (Union[int, ParameterExpression]) – Pulse length in terms of the sampling period dt.

• amp (Union[float, ParameterExpression]) – The magnitude of the amplitude of the cosine wave. Wave range is [-amp,amp].

• phase (Union[float, ParameterExpression]) – The phase of the cosine wave (note that this is not equivalent to the angle of the complex amplitude).

• freq (Optional[Union[float, ParameterExpression]]) – The frequency of the cosine wave, in terms of 1 over sampling period. If not provided defaults to a single cycle (i.e :math:’frac{1}{text{duration}}’). The frequency is limited to the range $$\left(0,0.5\right]$$ (the Nyquist frequency).

• angle (Optional[Union[float, ParameterExpression]]) – The angle in radians of the complex phase factor uniformly scaling the pulse. Default value 0.

• 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.

Returns

ScalableSymbolicPulse instance.

Return type

ScalableSymbolicPulse