Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analysis of quantum coherence in bismuth-doped silicon: a system of
  strongly coupled spin qubits   There is growing interest in bismuth-doped silicon (Si:Bi) as an alternative
to the well-studied proposals for silicon based quantum information processing
(QIP) using phosphorus-doped silicon (Si:P). We focus here on the implications
of its anomalously strong hyperfine coupling. In particular, we analyse in
detail the regime where recent pulsed magnetic resonance experiments have
demonstrated the potential for orders of magnitude speedup in quantum gates by
exploiting transitions that are electron paramagnetic resonance (EPR) forbidden
at high fields. We also present calculations using a phenomenological Markovian
master equation which models the decoherence of the electron spin due to
Gaussian temporal magnetic field perturbations. The model quantifies the
advantages of certain "optimal working points" identified as the $df/dB=0$
regions, where $f$ is the transition frequency, which come in the form of
frequency minima and maxima. We show that at such regions, dephasing due to the
interaction of the electron spin with a fluctuating magnetic field in the $z$
direction (usually adiabatic) is completely removed.

34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci