Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vacuum-assisted generation and control of atomic coherences at x-ray
  energies   The control of light-matter interaction at the quantum level usually requires
coherent laser fields. But already an exchange of virtual photons with the
electromagnetic vacuum field alone can lead to quantum coherences, which
subsequently suppress spontaneous emission. We demonstrate such spontaneously
generated coherences (SGC) in a large ensemble of nuclei operating in the x-ray
regime, resonantly coupled to a common cavity environment. The observed SGC
originates from two fundamentally different mechanisms related to cooperative
emission and magnetically controlled anisotropy of the cavity vacuum. This
approach opens new perspectives for quantum control, quantum state engineering
and simulation of quantum many-body physics in an essentially decoherence-free
setting.

9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph