Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Recovering the full dimensionality of hyperentanglement in collinear
  photon pairs   Exploiting hyperentanglement of photon pairs, that is, simultaneous
entanglement in multiple degrees of freedom(DOFs), increases the dimensionality
of Hilbert spaces for quantum information processing. However, generation of
hyperentangled photon pairs collinearlly, while produces high brightness,
results in a smaller Hilbert space due to the two photons being in the same
spatial mode. In this letter, we point out that one can recover the full
dimensionality of such hyperentanglement through a simple interference set up,
similar to the time-reversed Hong-Ou-Mandel (TR-HOM) process. Different from
the standard TR-HOM, we point out a critical phase condition has to be
satisfied in order to recover the hyperentanglement. We theoretically analyze
the realization of this approach and discuss the feasibility of generating
truly hyperentangled photon pairs. Our proposed approach does not require
post-selection and hence enables efficient hyper-entangled photon pairs
generation for high-dimensional quantum applications.

20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat