Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of a macroscopic entangled coherent state using quantum
  memories in circuit QED   $W$-type entangled states can be used as quantum channels for, e.g., quantum
teleportation, quantum dense coding, and quantum key distribution. In this
work, we propose a way to generate a macroscopic $W$-type entangled coherent
state using quantum memories in circuit QED. The memories considered here are
nitrogen-vacancy center ensembles (NVEs), each located in a different cavity.
This proposal does not require initially preparing each NVE in a coherent state
instead of a ground state, which should significantly reduce its experimental
difficulty. For most of the operation time, each cavity remains in a vacuum
state, thus decoherence caused by the cavity decay and the unwanted
inter-cavity crosstalk are greatly suppressed. Moreover, only one
external-cavity coupler qubit is needed. This method is quite general and can
be applied to generate the proposed $W$ state with atomic ensembles or other
spin ensembles distributed in different cavities.

19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph