Pulse

class pulser.pulse.Pulse(amplitude, detuning, phase, post_phase_shift=0.0)

Bases: object

A generic pulse.

In Pulser, a Pulse is a modulation of a frequency signal in amplitude and/or frequency, with a specific phase, over a given duration. Amplitude and frequency modulations are defined by Waveform child classes. Frequency modulation is determined by a detuning waveform, which describes the shift in frequency from the channel’s central frequency over time. If either quantity is constant throughout the entire pulse, use the ConstantDetuning, ConstantAmplitude or ConstantPulse class method to create it. If defining the pulse’s phase modulation is preferred over its frequency modulation, use Pulse.ArbitraryPhase().

Note

We define the amplitude of a pulse to be its Rabi frequency, \(\Omega\), in rad/µs. Equivalently, the detuning is \(\delta\), also in rad/µs.

Parameters:

• amplitude (Waveform | Parametrized) – The pulse amplitude waveform (in rad/µs).

• detuning (Waveform | Parametrized) – The pulse detuning waveform (in rad/µs).

• phase (float | TensorLike | Parametrized) – The pulse phase (in radians).

• post_phase_shift (float | Parametrized, default: 0.0) – Optionally lets you add a phase shift(in rad) immediately after the end of the pulse. This allows for enconding of arbitrary single-qubit gates into a single pulse (see Sequence.phase_shift() for more information).

Attributes

duration	The duration of the pulse (in ns).
post_phase_shift
amplitude
detuning
phase

Methods

ArbitraryPhase	Pulse with an arbitrary phase waveform.
ConstantAmplitude	Pulse with a constant amplitude and a detuning waveform.
ConstantDetuning	Creates a Pulse with an amplitude waveform and a constant detuning.
ConstantPulse	Pulse with a constant amplitude and a constant detuning.
draw	Draws the pulse's amplitude and frequency waveforms.
fall_time	Calculates the extra time needed to ramp down to zero.
get_full_duration	Calculates the pulse's full duration after output modulation.

Signatures

classmethod ArbitraryPhase(cls, amplitude, phase, post_phase_shift=0.0)

Pulse with an arbitrary phase waveform.

Parameters:

• amplitude (Waveform | Parametrized) – The amplitude waveform (in rad/µs).

• phase (Waveform | Parametrized) – The phase waveform (in rad).

• post_phase_shift (float | Parametrized, default: 0.0) – Optionally lets you add a phase shift (in rad) immediately after the end of the pulse.

Note

Due to how the Hamiltonian is defined in Pulser, the phase and detuning are related by

\[\phi(t) = \phi_c - \sum_{k=0}^{t} \delta(k)\]

where \(\phi_c\) is the pulse’s constant phase offset. From a given phase waveform, we extract the phase offset and detuning waveform that respect this formula for every sample of \(\phi(t)\) and use these quantities to define the Pulse.

Warning

Except when the phase waveform is a ConstantWaveform or a RampWaveform, the extracted detuning waveform will be a CustomWaveform. This makes the Pulse uncapable of automatically extending its duration to fit a channel’s clock period.

Return type:

Pulse

Returns:

A regular Pulse, with the phase waveform translated into a detuning waveform and a constant phase offset.

classmethod ConstantAmplitude(cls, amplitude, detuning, phase, post_phase_shift=0.0)

Pulse with a constant amplitude and a detuning waveform.

Parameters:

• amplitude (float | TensorLike | Parametrized) – The pulse amplitude value (in rad/µs).

• detuning (Waveform | Parametrized) – The pulse detuning waveform (in rad/µs).

• phase (float | TensorLike | Parametrized) – The pulse phase (in radians).

• post_phase_shift (float | Parametrized, default: 0.0) – Optionally lets you add a phase shift (in rad) immediately after the end of the pulse.

Return type:

Pulse

classmethod ConstantDetuning(cls, amplitude, detuning, phase, post_phase_shift=0.0)

Creates a Pulse with an amplitude waveform and a constant detuning.

Parameters:

• amplitude (Waveform | Parametrized) – The pulse amplitude waveform (in rad/µs).

• detuning (float | TensorLike | Parametrized) – The detuning value (in rad/µs).

• phase (float | TensorLike | Parametrized) – The pulse phase (in radians).

• post_phase_shift (float | Parametrized, default: 0.0) – Optionally lets you add a phase shift (in rad) immediately after the end of the pulse.

Return type:

Pulse

classmethod ConstantPulse(duration, amplitude, detuning, phase, post_phase_shift=0.0)

Pulse with a constant amplitude and a constant detuning.

Parameters:

• duration (int | Parametrized) – The pulse duration (in ns).

• amplitude (float | TensorLike | Parametrized) – The pulse amplitude value (in rad/µs).

• detuning (float | TensorLike | Parametrized) – The detuning value (in rad/µs).

• phase (float | TensorLike | Parametrized) – The pulse phase (in radians).

• post_phase_shift (float | Parametrized, default: 0.0) – Optionally lets you add a phase shift (in rad) immediately after the end of the pulse.

Return type:

Pulse

draw()

Draws the pulse’s amplitude and frequency waveforms.

Return type:

None

fall_time(channel, in_eom_mode=False)

Calculates the extra time needed to ramp down to zero.

Return type:

int

get_full_duration(channel, in_eom_mode=False)

Calculates the pulse’s full duration after output modulation.

The full duration of a pulse is the total time between the start of the input signal and the end of the output signal, as shown in the sequence.

Parameters:

• channel (Channel) – The pulse executing the channel.

• in_eom_mode (bool, default: False) – Whether the pulse is executed in EOM mode.

Return type:

int

property duration: int

The duration of the pulse (in ns).