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@ARTICLE{Valentini:1038563,
      author       = {Valentini, Marco and van Mourik, Martin W. and Butt,
                      Friederike and Wahl, Jakob and Dietl, Matthias and Pfeifer,
                      Michael and Anmasser, Fabian and Colombe, Yves and Rössler,
                      Clemens and Holz, Philip and Blatt, Rainer and Müller,
                      Markus and Monz, Thomas and Schindler, Philipp},
      title        = {{D}emonstration of two-dimensional connectivity for a
                      scalable error-corrected ion-trap quantum processor
                      architecture},
      reportid     = {FZJ-2025-01546, arXiv:2406.02406},
      year         = {2025},
      note         = {23 pages, 19 figures (15 in main text, 4 in appendices)},
      abstract     = {A major hurdle for building a large-scale quantum computer
                      is to scale up the number of qubits while maintaining
                      connectivity between them. In trapped-ion devices, this
                      connectivity can be provided by physically moving
                      subregisters consisting of a few ions across the processor.
                      The topology of the connectivity is given by the layout of
                      the ion trap where one-dimensional and two-dimensional
                      arrangements are possible. Here, we focus on an architecture
                      based on a rectangular two-dimensional lattice, where each
                      lattice site contains a subregister with a linear string of
                      ions. We refer to this architecture as the Quantum Spring
                      Array (QSA). Subregisters placed in neighboring lattice
                      sites can be coupled by bringing the respective ion strings
                      close to each other while avoiding merging them into a
                      single trapping potential. Control of the separation of
                      subregisters along one axis of the lattice, known as the
                      axial direction, uses quasi-static voltages, while the
                      second axis, the radial, requires control of radio frequency
                      signals. In this work, we investigate key elements of the 2D
                      lattice quantum computation architecture along both axes: We
                      show that the coupling rate between neighboring lattice
                      sites increases with the number of ions per site and the
                      motion of the coupled system can be resilient to noise. The
                      coherence of the coupling is assessed, and an entangled
                      state of qubits in separate trapping regions along the
                      radial axis is demonstrated. Moreover, we demonstrate
                      control over radio frequency signals to adjust radial
                      separation between strings, and thus tune their coupling
                      rate. We further map the 2D lattice architecture to code
                      primitives for fault-tolerant quantum error correction,
                      providing a step towards a quantum processor architecture
                      that is optimized for large-scale fault-tolerant operation.},
      cin          = {PGI-2},
      cid          = {I:(DE-Juel1)PGI-2-20110106},
      pnm          = {5221 - Advanced Solid-State Qubits and Qubit Systems
                      (POF4-522)},
      pid          = {G:(DE-HGF)POF4-5221},
      typ          = {PUB:(DE-HGF)25},
      eprint       = {2406.02406},
      howpublished = {arXiv:2406.02406},
      archivePrefix = {arXiv},
      SLACcitation = {$\%\%CITATION$ = $arXiv:2406.02406;\%\%$},
      url          = {https://juser.fz-juelich.de/record/1038563},
}