Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin noise spectroscopy beyond thermal equilibrium and linear response   Per the fluctuation-dissipation theorem, the information obtained from spin
fluctuation studies in thermal equilibrium is necessarily constrained by the
system's linear response functions. However, by including weak radiofrequency
magnetic fields, we demonstrate that intrinsic and random spin fluctuations
even in strictly unpolarized ensembles \emph{can} reveal underlying patterns of
correlation and coupling beyond linear response, and can be used to study
non-equilibrium and even multiphoton coherent spin phenomena. We demonstrate
this capability in a classical vapor of $^{41}$K alkali atoms, where spin
fluctuations alone directly reveal Rabi splittings, the formation of Mollow
triplets and Autler-Townes doublets, ac Zeeman shifts, and even nonlinear
multiphoton coherences.

7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
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