Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universal Dynamical Decoupling: Two-Qubit States and Beyond   Uhrig's dynamical decoupling pulse sequence has emerged as one universal and
highly promising approach to decoherence suppression. So far both the
theoretical and experimental studies have examined single-qubit decoherence
only. This work extends Uhrig's universal dynamical decoupling from one-qubit
to two-qubit systems and even to general multi-level quantum systems. In
particular, we show that by designing appropriate control Hamiltonians for a
two-qubit or a multi-level system, Uhrig's pulse sequence can also preserve a
generalized quantum coherence measure to the order of $1+O(T^{N+1})$, with only
$N$ pulses. Our results lead to a very useful scheme for efficiently locking
two-qubit entangled states. Future important applications of Uhrig's pulse
sequence in preserving the quantum coherence of multi-level quantum systems can
also be anticipated.

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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
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The categories of this paper are: hep-ex
1
The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
3
The categories of this paper are: physics