fr., 16.07.2010 kl. 13.25 -0700, skrev Brian Granger:
> Hi,
>
> Currently in secondquant and quantum we are making Bra and Ket
> subclasses of State:
>
> class State(Expr):
> class Bra(State):
> class Ket(State):
>
> the other option would be to make the ket/bra-ness an option:
>
> bra = State('alpha', bra=True)
>
> The advantage of this approach is that things like dagger can
> automatically know how to build the bra or ket from the ket or bra,
> without having to know what the appropriate class is. Also, the
> inheritance diagram for states is getting to be pretty messy when we
> introduce TensorProducts and this keeps it simple. We could still
> have Bra/Ket factory functions that build State instances with the
> right options. Thoughts?
I don't see any problems with the approach you suggest, but your
question inspired me to think a bit about dual states.
Another approach entirely is to consider bra states as *operators*, and
not states at all. I've seen some texts treating bras as operators
mapping kets to the complex plane (as opposed to the usual operators
mapping kets to kets.). I don't know exactly where that would lead with
respect to a Sympy implementation, but it could be worth to consider it.
I don't have strong opinions about this, I just wanted to share my
thoughts.
Cheers,
Øyvind
>
> Brian
>
> --
> Brian E. Granger, Ph.D.
> Assistant Professor of Physics
> Cal Poly State University, San Luis Obispo
> bgran...@calpoly.edu
> elliso...@gmail.com
>
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