Bifurcation of Driven Chua's Circuit
That bifurcation map can't be plotted in LTspice[*]. It involves running the simulation until the transients died out, then sampling the steady-state values at the end, which will form one slice on the Y-axis. Then a perturbance is introduced and the process is repeated for another slice.
To illustrate, consider the well-known logistic map, with the formula:
$$y_k=R\,y_{k-1}(1-y_{k-1})$$
For some given initial conditions, say \$R=2.7\$ and \$y_0=0.7\$, running the equation over some 30 steps results in this graph:

The last value is considered to be in steady-state, so it's stored. Then the same process is repeated, until the result is the one in the Wikipedia's logistic map's page.
If I read it correctly, the same process is done here. They start with a fixed value, to force the system to start in a known, stable region, forcing the other regions off, then they step the value (the first pulse), let the system stabilize, then measure, then the system is reset, then rinse and repeat. Note that they are not using the classic Chua's circuit, but a modified one.

[*]Only one &quot;slice&quot; could be plotted in LTspice: a step source can be used as the input, and the simulation time adjusted to include only the last, steady-state part. Then use .opt baudrate=&lt;...&gt;. You'll be sorely disappointed, though. Best use Octave/Matlab/Scilab/whatever else for this task; SPICE is not the language for bifurcation maps.