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Pointer states via engineered dissipation

Kaveh Khodjasteh, Viatcheslav V. Dobrovitski, and Lorenza Viola
Phys. Rev. A 84, 022336 – Published 25 August 2011
Physics logo See Synopsis: Pointing toward stability

Abstract

Pointer states are long-lasting high-fidelity states in open quantum systems. We show how any pure state in a non-Markovian open quantum system can be made to behave as a pointer state by suitably engineering the coupling to the environment via open-loop periodic control. Engineered pointer states are constructed as approximate fixed points of the controlled open-system dynamics, in such a way that they are guaranteed to survive over a long time with a fidelity determined by the relative precision with which the dynamics is engineered. We provide quantitative minimum-fidelity bounds by identifying symmetry and ergodicity conditions that the decoherence-inducing perturbation must obey in the presence of control, and develop explicit pulse sequences for engineering any desired set of orthogonal states as pointer states. These general control protocols are validated through exact numerical simulations as well as semiclassical approximations in realistic single- and two-qubit dissipative systems. We also examine the role of control imperfections, and show that while pointer-state engineering protocols are highly robust in the presence of systematic pulse errors, the latter can also lead to unintended pointer-state generation in dynamical decoupling implementations, explaining the initial-state selectivity observed in recent experiments.

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  • Received 23 June 2011

DOI:https://doi.org/10.1103/PhysRevA.84.022336

©2011 American Physical Society

Synopsis

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Pointing toward stability

Published 25 August 2011

A theoretical proposal shows how pure quantum states can be turned into long-lasting states that are protected from decoherence.

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Authors & Affiliations

Kaveh Khodjasteh1, Viatcheslav V. Dobrovitski2, and Lorenza Viola1

  • 1Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755, USA
  • 2Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA

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Issue

Vol. 84, Iss. 2 — August 2011

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