Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantized conductance in an AlAs 2D electron system quantum point
  contact   We report experimental results on a quantum point contact (QPC) device formed
in a wide AlAs quantum well where the two-dimensional electrons occupy two
in-plane valleys with elliptical Fermi contours. To probe the closely-spaced,
one-dimensional electric subbands, we fabricated a point contact device defined
by shallow-etching and a top gate that covers the entire device. The
conductance versus top gate bias trace shows a series of weak plateaus at
integer multiples of $2e^2/h$, indicating a broken valley degeneracy in the QPC
and implying the potential use of QPC as a simple "valley filter" device. A
model is presented to describe the quantized energy levels and the role of the
in-plane valleys in the transport. We also observe a well-developed conductance
plateau near $0.7x2e^2/h$ which may reflect the strong electron-electron
interaction in the system.

17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg