title: Nonperturbative leakage elimination operators and control of a three-level system.
abstract: Dynamical decoupling operations have been shown to reduce errors in quantum information processing. Leakage from an encoded subspace to the rest of the system space is a particularly serious problem for which leakage elimination operators (LEOs) were introduced. Here we provide an analysis of nonideal pulses, rather than the well-understood idealization or bang-bang controls. Under realistic conditions, we show that these controls will provide the same protection from errors as idealized controls. Our work indicates that the effectiveness of LEOs depends on the integral of the pulse sequence in the time domain, which has been missing because of the idealization of pulse sequences. Our results are applied to a three-level system for the nitrogen-vacancy centers under an external magnetic field and are illustrated by the fidelity dynamics of LEO sequences, ranging from regular rectangular pulses, random pulses, and even disordered (noisy) pulses.
authors.affiliation: Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, Changchun 130012, Jilin, China.|Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), P.O. Box 644, 48080 Bilbao, Spain.
authors.forename: Jun
authors.initials: J
authors.lastname: Jing
authors.affiliation: Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), P.O. Box 644, 48080 Bilbao, Spain.|Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain.
authors.forename: Lian-Ao
authors.initials: LA
authors.lastname: Wu
authors.affiliation: Physics Department, Southern Illinois University, Carbondale, Illinois 62901-4401, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Byrd
authors.affiliation: Beijing Computational Science Research Center, Beijing 100084, China.
authors.forename: J Q
authors.initials: JQ
authors.lastname: You
authors.affiliation: Center for Controlled Quantum Systems and Department of Physics and Engineering Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
authors.forename: Ting
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Physics, Ocean University of China, Qingdao 266100, China.
authors.forename: Zhao-Ming
authors.initials: ZM
authors.lastname: Wang