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@ARTICLE{Oshnik:904649,
      author       = {Oshnik, Nimba and Rembold, Phila and Calarco, Tommaso and
                      Montangero, Simone and Neu, Elke and Müller, Matthias},
      title        = {{R}obust {M}agnetometry with {S}ingle {NV} {C}enters via
                      {T}wo-step {O}ptimization},
      reportid     = {FZJ-2021-06218},
      year         = {2021},
      note         = {16 pages, 11 figures},
      abstract     = {The negatively charged nitrogen-vacancy (NV) center in
                      diamond is a widely-used platform in the rapidly growing
                      field of quantum technologies. In particular, NV centers
                      near the surface of the diamond can offer nanoscale
                      resolution as they can be brought into proximity of the
                      sample. However, these shallow single NV centers experience
                      considerable noise from the surface in addition to the
                      perturbation from the spin bath in the bulk diamond crystal.
                      This lowers the spin coherence and lifetimes leading to
                      limited sensing capabilities. This work presents a two-step
                      approach to improve both the spin initialization/readout and
                      the spin manipulation processes by applying optimization
                      algorithms to the laser and microwave controls. The goal is
                      to increase the NV's readout contrast aiming for control
                      pulses that are robust against power variation. With the
                      assistance of feedback-based (closed-loop) optimization,
                      limitations imposed by experimental imperfections and
                      unknown system parameters are inherently considered. For
                      pulsed ODMR-measurements, the optimization leads to
                      sensitivities staying below $1\,\mu$ T\,Hz$^{-\frac{1}{2}}$
                      for an 83\\% decrease in the control power, increasing the
                      robustness by approximately one third compared to the
                      original sequence. Furthermore, we report sensitivities
                      below 100\,nT\,Hz$^{-\frac{1}{2}}$ for Ramsey measurements,
                      where optimized control pulses result in a two-fold
                      improvement in the sensitivity. Both schemes were optimized
                      for DC magnetic field sensing over a large range of control
                      amplitudes. Such optimized sensing schemes are suitable for
                      a variety of magnetometry setups that require robustness,
                      e.g. (inhomogeneous) ensembles of NV centers, or NV scanning
                      probes operating at different distances from the MW
                      antenna.},
      cin          = {PGI-8},
      cid          = {I:(DE-Juel1)PGI-8-20190808},
      pnm          = {5221 - Advanced Solid-State Qubits and Qubit Systems
                      (POF4-522)},
      pid          = {G:(DE-HGF)POF4-5221},
      typ          = {PUB:(DE-HGF)25},
      eprint       = {2111.12684},
      howpublished = {arXiv:2111.12684},
      archivePrefix = {arXiv},
      SLACcitation = {$\%\%CITATION$ = $arXiv:2111.12684;\%\%$},
      url          = {https://juser.fz-juelich.de/record/904649},
}