Quantum feedback for rapid state preparation in the presence of control imperfections

Date

2011

Authors

Combes, Joshua
Wiseman, H M

Journal Title

Journal ISSN

Volume Title

Publisher

Institute of Physics Publishing

Abstract

Quantum feedback control protocols can improve the operation of quantum devices. Here we examine the performance of a purification protocol when there are imperfections in the controls. The ideal feedback protocol produces an x-eigenstate from a mixed state in the minimum time, and is known as rapid state preparation. The imperfections we examine include time delays in the feedback loop, finite strength feedback, calibration errors and inefficient detection. We analyse these imperfections using the Wiseman-Milburn feedback master equation and related formalism. We find that the protocol is most sensitive to time delays in the feedback loop. For systems with slow dynamics, however, our analysis suggests that inefficient detection would be the bigger problem. We also show how system imperfections, such as dephasing and damping, can be included in a model via the feedback master equation.

Description

Keywords

Keywords: Calibration error; Dephasing; Feed-back loop; Feedback protocol; Master equations; Minimum time; Mixed state; Purification protocol; Quantum device; Quantum feedback; Quantum feedback control; Slow dynamics; State preparation; System imperfections; Quantu

Citation

Source

Journal of Physics B: Atomic, Molecular and Optical Physics

Type

Journal article

Book Title

Entity type

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DOI

10.1088/0953-4075/44/15/154008

Restricted until

2037-12-31