Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Private Database Queries Using Quantum States with Limited Coherence
  Times   We describe a method for private database queries using exchange of quantum
states with bits encoded in mutually incompatible bases. For technology with
limited coherence time, the database vendor can announce the encoding after a
suitable delay to allow the user to privately learn one of two items in the
database without the ability to also definitely infer the second item. This
quantum approach also allows the user to choose to learn other functions of the
items, such as the exclusive-or of their bits, but not to gain more information
than equivalent to learning one item, on average. This method is especially
useful for items consisting of a few bits by avoiding the substantial overhead
of conventional cryptographic approaches.

22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph