Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Decoherence in quantum walks - a review   The development of quantum walks in the context of quantum computation, as
generalisations of random walk techniques, led rapidly to several new quantum
algorithms. These all follow unitary quantum evolution, apart from the final
measurement. Since logical qubits in a quantum computer must be protected from
decoherence by error correction, there is no need to consider decoherence at
the level of algorithms. Nonetheless, enlarging the range of quantum dynamics
to include non-unitary evolution provides a wider range of possibilities for
tuning the properties of quantum walks. For example, small amounts of
decoherence in a quantum walk on the line can produce more uniform spreading (a
top-hat distribution), without losing the quantum speed up. This paper reviews
the work on decoherence, and more generally on non-unitary evolution, in
quantum walks and suggests what future questions might prove interesting to
pursue in this area.

6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex