Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ground state and rotational properties of two-dimensional self-bound
  quantum droplets   We consider a two-dimensional self-bound quantum droplet, which consists of a
mixture of two Bose-Einstein condensates. We start with the ground state, and
then turn to the rotational response of this system, in the presence of an
external (harmonic) potential. We identify various phases, depending on the
atom number, the strength of the external confinement and the angular momentum.
These include center of mass excitation, ghost vortices, as well as vortices of
single and multiple quantization. According to our results, this is an
excellent system for the study of superfluid states.

2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex