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 threelevel 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.
Reference: J. Jing, L.-A. Wu, and M. Byrd, J. Q. You, T. Yu, and Z.-M. Wang, PHYSICAL REVIEW LETTERS 114, 190502 (2015).
Dr Jun Jing got his PhD degree in 2007 at Physics Department of Shanghai Jiaotong University. Afterwards, he received a job as a lecturer at Shanghai University and got promoted as an associate professor in 2009. From 2010 to 2014, he worked as a research associate (post-Doc) at Stevens Institute of Technology, New Jersey, a visiting scholar at Department of Theoretical Physics and History of Science, The Basque Country University, Spain, and a research scientist at Physics Department, University at Buffalo, The State University of New York, in turn. Now (from June 2014) he is a full professor at the institute of Atomic and Molecular Physics, Jilin University. His works involve with the field of open quantum system dynamics, quantum control, quantum information, quantum entanglement, decoherence process of AMO systems and artificial atomic systems, geometrical quantum computing and adiabatic passage of open quantum system.
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