Rapid-state purification protocols for a Cooper pair box

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Title Rapid-state purification protocols for a Cooper pair box
Author Griffith, E. J.; Hill, C. D.; Ralph, J. F.; Wiseman, Howard Mark; Jacobs, Kurt
Journal Name Physical Review B: Condensed Matter and Materials Physics
Year Published 2007
Place of publication Ridge, NY
Publisher American Physical Society
Abstract 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.
Peer Reviewed Yes
Published Yes
Publisher URI http://prb.aps.org/
Alternative URI http://dx.doi.org/10.1103/PhysRevB.75.014511
Copyright Statement Copyright 2007 American Physical Society. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Volume 75
Page from 014511-1
Page to 014511-12
ISSN 1098-0121
Date Accessioned 2008-02-25
Language en_AU
Research Centre Centre for Quantum Dynamics
Faculty Faculty of Science, Environment, Engineering and Technology
URI http://hdl.handle.net/10072/18283
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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