Bilayer ion trap design for 2D arrays

Abstract

Junctions are fundamental elements that support qubit locomotion in two-dimensional ion trap
arrays and enhance connectivity in emerging trapped-ion quantum computers. In surface ion traps
they have typically been implemented by shaping radio frequency (RF) electrodes in a single plane
to minimize the disturbance to the pseudopotential. However, this method introduces issues related
to RF lead routing that can increase power dissipation and the likelihood of voltage breakdown.
Here, we propose and simulate a novel two-layer junction design incorporating two perpendicularly
rotoreflected (rotated, then reflected) linear ion traps. The traps are vertically separated, and create a trapping potential
between their respective planes. The orthogonal orientation of the RF electrodes of each trap relative
to the other provides perpendicular axes of confinement that can be used to realize transport in
two dimensions. While this design introduces manufacturing and operating challenges, as now two
separate structures have to be precisely positioned relative to each other in the vertical direction
and optical access from the top is obscured, it obviates the need to route RF leads below the top
surface of the trap and eliminates the pseudopotential bumps that occur in typical junctions. In
this paper the stability of idealized ion transfer in the new configuration is demonstrated, both by
solving the Mathieu equation analytically to identify the stable regions and by numerically modeling
ion dynamics. Our novel junction layout enhances the flexibility of microfabricated ion trap control
to enable large-scale trapped-ion quantum computing.