Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Voltage-Selective Bi-directional Polarization and Coherent Rotation of
  Nuclear Spins in Quantum Dots   We proposed and demonstrated that the nuclear spins of the host lattice in
GaAs double quantum dots can be strongly polarized in either of two opposite
directions, parallel or antiparallel to an external magnetic field. The
direction is selected simply by adjusting the dc source-drain voltage of the
device. This nuclear polarization manifests itself by repeated controlled
electron-nuclear spin scattering in the Pauli spin blockade state. Polarized
nuclei are also controlled coherently by means of nuclear magnetic resonance
(NMR). This work confirmed that the nuclear spins in quantum dots are indeed
long-lived quantum states with a coherence time of up to 1 ms, and may be a
promising resource for quantum information processing such as quantum memories
for electron spin qubits.

13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
19
The categories of this paper are: eess
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th