Reference.Variables.time.pulse

Variable "time.pulse" in MATLAB/Octave version of WavePacket

Specifies the electric field(s) to be used to externally control a quantum system by interaction with a dipole moment and/or a polarizability. The time-dependence of the electric field is constructed as a sum of pulses each of which is given by the expression F(t) = A(t−τ) cos(ω(t−τ)⋅(t−τ)+φ₀) with amplitude (pulse shape) specified by scalar or vector A(t), delay τ, and phase φ₀. The carrier frequency is given by ω(t) = ω₀ + αt + ½βt², optionally with linear and/or quadratic chirp.

In the following, we give a complete list of the pulse shape classdef's along with their settable properties, see also the corresponding package folder.

efi.generic	generic (parent) classdef from which all of the classdef's below inherit	default
fwhm	Full width at half maximum	0
ampli	Maximum amplitude F0 of the pulse: scalar or row(!) vector ¹	0
delay	Delay time τ of the center of the pulse	0
frequ	Constant part of the (carrier) frequency ω0 of the pulse	0
phase	Phase shift φ0 of the pulse	0
linear	Linear part α of the chirp	0
quadratic	Quadratic part β of the chirp	0

¹ Note that the lengths of the amplitude row(!) vectors (number of polarization directions) should be equal for all pulses.

efi.gauss	Gaussian envelope g(t−τ) = exp(−(t−τ)²/(2σ²)
fwhm	The full width at half maximum is related to the variance σ = FWHM / √(8 ln 2).

efi.recta	Rectangular pulse g(t−τ) = Θ(abs(t−τ)−w/2)
fwhm	The length w of the pulse.

efi.sin^2	Squared sine shape g(t−τ) = sin²(π(t−τ)/(2T)+π/2)= cos²(π(t−τ)/(2T))
fwhm	The half-width T of the pulse.

Note: The shifted sin² pulse shape is actually rather a cos² but we keep this notation for reasons of backward-compatibility.

efi.inter	interpolates the shape function g(t) from data points in an external file (see the manual for details on interpolation). Outside of the interval of given time values, the electric field is set to 0.
file	Name of file from which to load the tabulated shape function. If complex fields are to be used, then the real and imaginary part should be in the second and third column, respectively. Time is always in the first column.
method	The method to use for interpolation. Method 'spline' is recommended which is also the default.
t_conv	Optional: Conversion factor to apply to the time values. The values in the file are given in units of ''t_conv'' atomic units. Default is 1.
f_conv	Optional: Conversion factor to apply to the field values. The values in the file are given in units of ''f_conv'' atomic units. Default is 1.

Trick: If not only the shape function but the whole pulse including the oscillations (i.e. electric field versus time) shall be interpolated from tabulated data, then all other variables have to be set to dummy values in order to suppress the oscillatory part.

time.pulse{1} = efi.inter; 
time.pulse{1}.ampli  = 1;       
time.pulse{1}.delay  = 0;       
time.pulse{1}.frequ  = 0;       
time.pulse{1}.phase  = 0;
time.pulse{1}.file   = 'field.dat'; 
time.pulse{1}.method = 'spline';