Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: When is a Quantum Cellular Automaton (QCA) a Quantum Lattice Gas
  Automaton (QLGA)?   Quantum cellular automata (QCA) are models of quantum computation of
particular interest from the point of view of quantum simulation. Quantum
lattice gas automata (QLGA - equivalently partitioned quantum cellular
automata) represent an interesting subclass of QCA. QLGA have been more deeply
analyzed than QCA, whereas general QCA are likely to capture a wider range of
quantum behavior. Discriminating between QLGA and QCA is therefore an important
question. In spite of much prior work, classifying which QCA are QLGA has
remained an open problem. In the present paper we establish necessary and
sufficient conditions for unbounded, finite Quantum Cellular Automata (QCA)
(finitely many active cells in a quiescent background) to be Quantum Lattice
Gas Automata (QLGA). We define a local condition that classifies those QCA that
are QLGA, and we show that there are QCA that are not QLGA. We use a number of
tools from functional analysis of separable Hilbert spaces and representation
theory of associative algebras that enable us to treat QCA on finite but
unbounded configurations in full detail.

26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: eess