Category Theory and Quantum Mechanics I am wondering if particle interactions in quantum theory can be modeled as a morphism between $2$ categories. 
My reasoning is that since the states of particles are modeled as vectors in a Hilbert space, given two Hilbert spaces, call them $A$ and $B$, the interaction could be described by a morphism $f$ between $A$ and $B$.
Suppose the category $C$ is given by $f:A\to B$ 
where $A$ is the Hilbert space containing the states of the $2$ particles. $\psi_1$ and $\psi_2$ and $B$ is the Hilbert space containing the states of the particles $\phi_1$ and $\phi_2$ after the interaction. 
So can particle interactions be understood in a category theoretic way, specifically the category of Hilbert Spaces?
 A: There is an excellent expository article on this by John Baez:
http://arxiv.org/abs/quant-ph/0404040
There is another article by Baez and Lauda on the more general topic of n-categories and their role in physics which is worth checking out:
http://arxiv.org/abs/0908.2469
Of course, for details you can check the references therein, but here are a few of note (in my opinion):
http://arxiv.org/abs/0808.1023
http://arxiv.org/abs/math/0601458
http://arxiv.org/abs/0706.0711
Also, as quantum mechanics can be viewed as a 1-dimensional quantum field theory, the categorical approach to QFT might be of interest to you.  In that regard, these references might be of interest:
http://arxiv.org/abs/q-alg/9503002
http://www-math.mit.edu/~lurie/papers/cobordism.pdf
One last thing to go with the theme of (higher) categorical physics: a few months back Urs Schreiber posted this article, which claims to have solved Hilbert's sixth problem (i.e. axiomatizing physics) by using the language of cohesive $\infty$-topoi.  It's a massive article that I've only read through a small portion of, but it definitely seems interesting.
