Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum nanoconstrictions fabricated by cryo-etching in encapsulated
  graphene   More than a decade after the discovery of graphene, ballistic transport in
nanostructures based on this intriguing material still represents a challenging
field of research in two-dimensional electronics. The presence of rough edges
in nanostructures based on this material prevents the appearance of truly
ballistic electron transport as theo\-re\-tically predicted and, therefore, not
well-developed plateaus of conductance have been revealed to date. In this work
we report on a novel implementation of the cryo-etching method, which enabled
us to fabricate graphene nanoconstrictions encapsulated between hexagonal boron
nitride thin films with unprecedented control of the structure edges. High
quality smooth nanometer-rough edges are characterized by atomic force
microscopy and a clear correlation between low roughness and the existence of
well-developed quantized conductance steps with the concomitant occurrence of
ballistic transport is found at low temperature. In par\-ti\-cu\-lar, we come
upon exact 2$e^{2}/h$ quantization steps of conductance at zero magnetic field
due to size quantization, as it has been theoretically predicted for truly
ballistic electron transport through graphene nanoconstrictions.

6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con