Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coherent coupling of a superconducting flux-qubit to an electron spin
  ensemble in diamond   Electron-spin nitrogen-vacancy color centers in diamond are a natural
candidate to act as a quantum memory for superconducting qubits because of
their large collective coupling and long coherence times. We report here the
first demonstration of strong coupling and coherent exchange of a single
quantum of energy between a flux-qubit and an ensemble of nitrogen-vacancy
color centers.

34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
1
The categories of this paper are: cs
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math