Precise qubit control beyond the rotating wave approximation

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Jochen Scheuer¹, Xi Kong^1,2, Ressa S. Said³, Jeson Chen⁴, Andrea Kurz¹, Luca Marseglia¹, Jiangfeng Du², Philip R Hemmer⁴, Simone Montangero³, Tommaso Calarco³, Boris Naydenov¹, Fedor Jelezko¹.

¹ Institut für Quantenoptik, Albert-Einstein-Allee 11, Universität Ulm, D-89069 Ulm, Germany
² Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, Peopleʼs Republic of China
³ Institut für Quanteninformationsverarbeitung, Albert-Einstein-Allee 11, Universität Ulm, D-89069 Ulm, Germany
⁴ Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA

Abstract.Fast and accurate quantum operations of a single spin in room-temperature solids are required in many modern scientific areas, for instance in quantum information, quantum metrology, and magnetometry. However, the accuracy is limited if the Rabi frequency of the control is comparable with the transition frequency of the qubit due to the breakdown of the rotating wave approximation (RWA). We report here an experimental implementation of a control method based on quantum optimal control theory which does not suffer from such restriction. We demonstrate the most commonly used single qubit rotations, i.e. (π/2)^- and π-pulses, beyond the RWA regime with high fidelity F_π/2^exp=0.95 ± 0.01 and F_π^exp=0.99 ± 0.016, respectively. They are in excellent agreement with the theoretical predictions, F_π/2^theory=0.9545 and F_π^theory=0.9986. Furthermore, we perform two basic magnetic resonance experiments both in the rotating and the laboratory frames, where we are able to deliberately 'switch' between the frames, to confirm the robustness of our control method. Our method is general, hence it may immediately find its wide applications in magnetic resonance, quantum computing, quantum optics, and broadband magnetometry.

BibTeX Record:


@article{1367-2630-16-9-093022,
  author={Jochen Scheuer and Xi Kong and Ressa S Said and Jeson Chen and Andrea Kurz and Luca Marseglia and Jiangfeng Du and Philip R
Hemmer and Simone Montangero and Tommaso Calarco and Boris Naydenov and Fedor Jelezko},
  title={Precise qubit control beyond the rotating wave approximation},
  journal={New Journal of Physics},
  volume={16},
  number={9},
  pages={093022},
  url={http://stacks.iop.org/1367-2630/16/i=9/a=093022},
  year={2014},
 }