Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rapid state purification protocols for a Cooper pair box   We propose techniques for implementing two different rapid state purification
schemes, within the constraints present in a superconducting charge qubit
system. Both schemes use a continuous measurement of charge (z) measurements,
and seek to minimize the time required to purify the conditional state. Our
methods are designed to make the purification process relatively insensitive to
rotations about the x-axis, due to the Josephson tunnelling Hamiltonian. The
first proposed method, based on the scheme of Jacobs [Phys. Rev. A 67,
030301(R) (2003)] uses the measurement results to control bias (z) pulses so as
to rotate the Bloch vector onto the x-axis of the Bloch sphere. The second
proposed method, based on the scheme of Wiseman and Ralph [New J. Phys. 8, 90
(2006)] uses a simple feedback protocol which tightly rotates the Bloch vector
about an axis almost parallel with the measurement axis. We compare the
performance of these and other techniques by a number of different measures.

33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph