Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Proposal for an Optical Implementation of an Universal Quantum Phase
  Gate   Large optical nonlinearities occurring in a coherently prepared atomic system
are shown to produce phase shifts of order $\pi$. Such an effect may be
observed in ultracold rubidium atoms where it could be feasibly exploited
toward the realization of a polarization phase gate.

14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
1
The categories of this paper are: cs
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat