Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why a hole is like a beam splitter--a general diffraction theory for
  multimode quantum states of light   Within the second-quantization framework, we develop a formalism for
describing a spatially multimode optical field diffracted through a spatial
mask and show that this process can be described as an effective interaction
between various spatial modes. We demonstrate a method to calculate the quantum
state in the diffracted optical field for any given quantum state in the
incident field. Using numerical simulations, we also show that with single-mode
squeezed-vacuum state input, the prediction of our theory is in qualitative
agreement with our experimental data. We also give several additional examples
of how the theory works, for various quantum input states, which may be easily
tested in the lab; including two single-mode squeezed vacuums, single- and
two-photon inputs, where we show the diffraction process produces two-mode
squeezed vacuum, number-path entanglement and a Hong-Ou-Mandel-like
effect--analogous to a beam splitter.

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The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom