Abstract
We propose the use of two-dimensional Penning trap arrays as a scalable platform for quantum simulation and quantum computing with trapped atomic ions. This approach involves placing arrays of microstructured electrodes defining static electric quadrupole sites in a magnetic field, with single ions trapped at each site and coupled to neighbors via the Coulomb interaction. We solve for the normal modes of ion motion in such arrays and derive a generalized multi-ion invariance theorem for stable motion even in the presence of trap imperfections. We use these techniques to investigate the feasibility of quantum simulation and quantum computation in fixed ion lattices. In homogeneous arrays, we show that sufficiently dense arrays are achievable, with axial, magnetron, and cyclotron motions exhibiting interion dipolar coupling with rates significantly higher than expected decoherence. With the addition of laser fields, these can realize tunable-range interacting spin Hamiltonians. We also show how local control of potentials allows isolation of small numbers of ions in a fixed array and can be used to implement high-fidelity gates. The use of static trapping fields means that our approach is not limited by power requirements as the system size increases, removing a major challenge for scaling which is present in standard radio-frequency traps. Thus, the architecture and methods provided here appear to open a path for trapped-ion quantum computing to reach fault-tolerant scale devices.
- Received 12 February 2019
- Revised 2 April 2020
- Accepted 4 June 2020
DOI:https://doi.org/10.1103/PhysRevX.10.031027
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Quantum devices can allow researchers to simulate physics and perform calculations that are beyond the reach of classical supercomputers, with applications in complex computational problems as well as the search for new materials and phenomena. One promising experimental approach uses atomic ions trapped using oscillating electric fields and controlled by laser light; however, this is difficult to scale into two dimensions. We propose a new setting for quantum simulation and computation that offers the possibility to realize arbitrary planar lattices of interacting ions. The approach combines microfabricated local static potentials for each ion with a macroscopic static magnetic field, giving rise to a highly reconfigurable system of “micro-Penning traps” that could be used to investigate a range of interesting physical phenomena. This approach is highly scalable, since static fields do not induce energy dissipation.
We describe the proposed experimental setting, and then provide details relevant to implementation. This includes optimal electrode geometries for dense packing of ions, a detailed description of the (nontrivial) normal modes of an array of many ions, as well as theory covering the engineering of effective spin-spin interactions, laser cooling, and the implementation of high-fidelity multiqubit gates in such a setup. As an added bonus, we generalize a 30-year-old invariance theorem for single ions, which finds much use in precision spectroscopy with Penning traps, to an arbitrary number of ions.
Our techniques and new experimental approach provide tools for quantum simulation and quantum computing, offering reduced technical requirements for realizing the large-scale systems that will be useful for realizing a quantum advantage over classical computing.
