Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reduction of Dissipative Nonlinear Conductivity of Superconductors by
  Static and Microwave Magnetic Fields   A theory of dissipative nonlinear conductivity, $\sigma_1(\omega,H)$, of
s-wave superconductors under strong electromagnetic fields at low temperatures
is proposed. Closed-form expressions for $\sigma_1(H)$ and the surface
resistance $R_s(\omega,H)$ are obtained in the nonequilibrium dirty limit for
which $\sigma_1(H)$ has a significant minimum as a function of a low-frequency
$(\hbar\omega\ll k_BT)$ magnetic field $H$. The calculated microwave
suppression of $R_s(H)$ is in good agreement with recent experiments on alloyed
Nb resonator cavities. It is shown that superimposed dc and ac fields,
$H=H_0+H_a\cos\omega t$, can be used to reduce ac dissipation in thin film
nanostructures by tuning $\sigma_1(H_0)$ with the dc field.

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The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
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The categories of this paper are: nlin
2
The categories of this paper are: math