Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Can mesoscopic fluctuations reverse the supercurrent through a
  disordered Josephson junction?   We calculate the Josephson coupling energy $U_J(\phi)$ (related to the
supercurrent $I=(2e/\hbar) dU_J/d\phi$) for a disordered normal metal between
two superconductors with a phase difference $\phi$. We demonstrate that the
symmetry of the scattering matrix of non-interacting quasiparticles in zero
magnetic field implies that $U_J(\phi)$ has a minimum at $\phi=0$. A maximum
(that would lead to a $\pi$-junction or negative superfluid density) is
excluded for any realization of the disorder.

22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc