Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimal photon energies for initialization of hybrid spin quantum
  registers of NV centers in diamond   Initializing quantum registers with high fidelity is a fundamental
precondition for many applications like quantum information processing and
sensing. The electronic and nuclear spins of a Nitrogen-Vacancy (NV) center in
diamond form an interesting hybrid quantum register that can be initialized by
a combination of laser, microwave, and radio-frequency pulses. However, the
laser illumination, which is necessary for achieving electron spin
polarization, also has the unwanted side-effect of depolarizing the nuclear
spin. Here, we study how the depolarization dynamics of the $^{14}$N nuclear
spin depends on the laser wavelength. We show experimentally that excitation
with an orange laser (594 nm) causes significantly less nuclear spin
depolarization compared to the green laser (532 nm) typically used for
excitation and hence leads to higher nuclear spin polarization. This could be
because orange light excitation inhibits ionization of NV$^{0}$ into NV$^{-}$
and therefore suppresses one source of noise acting on the nuclear spin.

1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat