Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-qubit gates for decoherence-free qubits using a ring exchange
  interaction   It is known that it is possible to encode a logical qubit over many physical
qubits such that it is immune to the effects of collective decoherence, and it
is possible to perform universal quantum computation using these
`decoherence-free' qubits. However, current proposed methods of performing
gates on these encoded qubits could be difficult to implement, or could take
too much time to perform. Here we investigate whether exploiting ring-exchange
interactions, which may be naturally present, can simplify the implementation
of these gates in any way. Using a ring exchange interaction, we have found a
way to create a controlled-Z gate on the 4-qubit decoherence-free subspace and
the 3-qubit decoherence-free subsystem using a sequence with 5 pulses. This
could be useful in situations where simplicity is important or where ring
exchange interactions are prominent. We also investigate how timing errors and
magnetic field fluctuations affect the fidelity of this gate.

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The categories of this paper are: nlin
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: stat
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
1
The categories of this paper are: cs
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th