Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultra-fast multi-qubit global-entangling gates without individual
  addressing of trapped ions   We propose and study how to increase the speed of the entangling gates with
trapped ions while maintaining high fidelities from two aspects. First, we find
a scheme to increase the speed of a two-qubit gate without the limitation of
the trap frequency, which was considered the fundamental limit. Second, we
simultaneously study the possibility and speed limit in applying entangling
gates for more than two qubits, the global entangling gates. For the speedup,
we explore modulating various control parameters such as phases and
intensities, and applying multiple-frequency laser beams for the gate
operations. In particular, in order to avoid infinite terms from carrier
transitions, we focus on phase-insensitive gates, equivalent to light shift
gates. We find that if phase modulation is included, the gate speed can be
increased without the problem of infidelity caused by excessively large
excitation of motional mode beyond the limit of Lamb-Dicke approximation. We
also find that, by combining phase and intensity modulations, global entangling
gates can be performed close to the limit of the trap frequency without
individual addressing requirements. Furthermore, our gates are robust to the
fluctuation of initial motional phases which are considered uncontrollable in
the phase-insensitive gate scheme.

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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas