Custom bounds on the blockade radius

[HGSilveri]

From my point of view, the user's access to the Rydberg blockade radius is still a little rough. It's strange to start with the register and then not really knowing whether your chosen pulse amplitudes actually give you the connectivity you're hoping for. I though it could be useful to have the option of setting the upper and/or lower bound of the blockade radius.

This would amount to translating the given blockade radius bounds to maximum Rabi frequency values and then filtering the pulses added to Rydberg channels to ensure this requirement is met. I have a feeling this might be a bit too restrictive and that perhaps one might not want all pulses in the Rydberg channels to obey these bounds, in which case the user would have to relax or give up on setting them altogether. For now, this is just an idea, the precise implementation might change.

@lhenriet @sebgrijalva I'm curious to hear your thoughts on this.

[HGSilveri]

Update: The above requirement is indeed too restrictive. A very minimal, but useful addition, would be to plot a line marking the \Omega threshold that enforces a given blockade radius minimum or maximum value.