Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Recent advances on quantum key distribution overcoming the linear secret
  key capacity bound   A crucial goal for quantum key distribution (QKD) is to transmit
unconditionally secure keys over long distances. Previous studies show that the
key rate of point-to-point QKD is limited by a secret key rate capacity bound,
and higher key rates would require quantum repeaters. In 2018, the seminal
twin-field (TF) QKD protocol was proposed to provide a remarkable solution to
overcoming the linear secret key capacity bound. This article presents an
up-to-date survey on recent developments in this area, including the security
proofs of phase-matching QKD and other TF-QKD type protocols, the theoretical
examinations of these protocols under realistic conditions, and the recent
experimental demonstrations.

21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom