[texhax] shift subscript without superscript

[Arno Trautmann]

Hi all,

this is a question that bugged me for a long time but I never dared to 
ask, nor did I find discussions of this so far. Consider the simple 
document:

\documentclass{minimal}
\begin{document}
\[a_i a_i^\dagger + b_i b_i^\dagger\]
\[a_i^{} a_i^\dagger + b_i^{\strut} b_i^\dagger\]
\end{document}

The first line is the normal input, and operators like this are used 
frequently in quantum physics. The disturbing point are the subscripts 
which are shifted further down if there is a superscript. I'm aware that 
this is a nice feature normally, but in this case I would like to see 
them at the same height.
In the second line of the example, the expression with the b operators 
shows the desired result, while the expressions with a operators show 
the three different positions of the subscript.
It is not very practical to add the ^{\strut} for every occurance – 
especially if you think of a document a colleague wrote and there are 
hundreds of these. Also, the \strut here causes too much space due to 
its excess height.

So, finally the question: Is it possible to default the subscript of any 
expression to be at the lowest position? (And, vice versa for the 
superscript to be at the topmost position?) I'll happily appreciate TeX 
hackery, package solutions, or Lua code … whatever helps :)

Best,
Arno