Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Priori Which-Way Information in Quantum Interference with Unstable
  Particles   If an unstable particle used in a two-path interference experiment decays
before reaching a detector, which-way information becomes available which
reduces the detected interference fringe visibility ${\cal V}$. Here we argue
that even when an unstable particle does {\em not} decay while in the
interferometer, {\em a priori} which-way information is still available in the
form of path predictability ${\cal P}$ which depends on the particle's decay
rate $\Gamma$. We further demonstrate that in a matter-wave Mach-Zehnder
interferometer using an excited atom with an appropriately tuned cavity, ${\cal
P}$ is related to ${\cal V}$ through the duality relation ${\cal P}^{2} + {\cal
V}^{2} = 1$.

32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio