Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum mechanical which-way experiment with an internal degree of
  freedom   For a particle travelling through an interferometer, the trade-off between
the available which-way information and the interference visibility provides a
lucid manifestation of the quantum mechanical wave-particle duality. Here we
analyze this relation for a particle possessing an internal degree of freedom
such as spin. We quantify the trade-off with a general inequality that paints
an unexpectedly intricate picture of wave-particle duality when internal states
are involved. Strikingly, in some instances which-way information becomes
erased by introducing classical uncertainty in the internal degree of freedom.
Furthermore, even imperfect interference visibility measured for a suitable set
of spin preparations can be sufficient to infer absence of which-way
information. General results are illustrated with a proof-of-principle single
photon experiment.

18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int