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Proceedings Paper

Rapid purification of a solid state charge qubit
Author(s): Jason F. Ralph; Elias J. Griffith; Charles D. Hill; Terence D. Clark
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Paper Abstract

This paper discusses the use of continuous weak measurement and quantum feedback for the rapid purification of the quantum state of a model solid state qubit: a superconducting Cooper pair box. The feedback algorithm uses Jacobs' rapid purification protocol, which starts with a completely mixed state and applies controls to rotate the qubit Bloch vector onto the plane orthogonal to the measurement axis. This rotation maximises the rate of increase of the average purity of the state but can require large changes in the control fields to produce the required rotation. Since solid state qubits have finite controls and feedback channels have limited bandwidth, such rotations may not be practical. This paper applies Jacobs' protocol to the Cooper pair box with realistic control fields.

Paper Details

Date Published: 12 May 2006
PDF: 8 pages
Proc. SPIE 6244, Quantum Information and Computation IV, 624403 (12 May 2006); doi: 10.1117/12.665403
Show Author Affiliations
Jason F. Ralph, The Univ. of Liverpool (United Kingdom)
Elias J. Griffith, The Univ. of Liverpool (United Kingdom)
Charles D. Hill, The Univ. of Liverpool (United Kingdom)
Terence D. Clark, The Univ. of Liverpool (United Kingdom)

Published in SPIE Proceedings Vol. 6244:
Quantum Information and Computation IV
Eric J. Donkor; Andrew R. Pirich; Howard E. Brandt, Editor(s)

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