Industrially microfabricated ion trap with 1 eV trap depth

Abstract

Scaling trapped-ion quantum computing will require robust trapping of at least hundreds of ions over long periods, while increasing the complexity and functionality of the trap itself. Symmetric three-dimensional (3D) structures enable high trap depth, but microfabrication techniques are generally better suited to planar structures that produce less ideal conditions for trapping. We present an ion trap fabricated on stacked 8-inch wafers in a large-scale micro-electro-mechanical system (MEMS) microfabrication process that provides reproducible traps at a large volume. Electrodes are patterned on the surfaces of two opposing wafers bonded to a spacer, forming a 3D structure with 2.5 µm standard deviation in alignment across the stack. We implement a design achieving a trap depth of 1 eV for a 40Ca+ ion held at 200 µm from either electrode plane. We characterize traps, achieving measurement agreement with simulations to within ±5% for mode frequencies spanning 0.6–3.8 MHz, and evaluate stray electric field across multiple trapping sites. We measure motional heating rates over an extensive range of trap frequencies, and temperatures, observing 40 phonons/s at 1 MHz and 185 K. This fabrication method provides a highly scalable approach for producing a new generation of 3D ion traps.

A high-fidelity quantum matter-link between ion-trap microchip modules

“…For comparison, 3-dimensional (3D) microfabricated ion traps constructed using wafer stacking techniques achieve an alignment accuracy between symmetric electrodes in the order of 10s of micrometers when aligned manually 34 , 35 . Employing precision-machined self-aligning features directly integrated within the wafers 36 , 37 , or semi-automatic bonding processes 38 , have since reduced the alignment imprecision to ≤2.5 μm. The present piezo actuator solution therefore offers a level of alignment accuracy between separate trap modules that is comparable to the level currently reached between electrodes on stacked wafer trap designs.…”

Mass Inversion at the Lifshitz Transition in Monolayer Graphene by Diffusive, High-Density, On-Chip Doping

“…43 In terms of commercial applications, the flip-chip method can be implemented to dope microfabricated ion traps designed for quantum computing. 44…”

“…The extension of the doping method presented here to other alkali dopants and target materials and devices may provide a means of exploring the physics of highly doped low-dimensional systems such as heavily doped black phosphorus which have been shown to exhibit bandgap modulation, closure, and inversion owing to an unusually strong Stark effect, , or alkali doped C 60 to synthesize high critical temperature superconductors . In terms of commercial applications, the flip-chip method can be implemented to dope microfabricated ion traps designed for quantum computing …”

Selective laser-induced etching for 3D ion traps

“…In principle, ion traps can be designed with a planar electrode geometry or with 3D electrode structures. 3D trap electrode structures offer deeper trap depths i.e., a larger trap potential, and less inharmonicity compared to planar electrode geometries but can be more complicated to fabricate 16,[25][26][27][28] . Combinations of different materials and fabrication methods are used to produce ion traps, for example silicon in combination with micro-electro-mechanical system microfabrication 25,26 , fused silica in combination with laser-enhanced etching 16 or alumina in combination with fs-laser ablation 27 .…”

“…However, to realize and use this advantage a sufficient system size with reduced error sources needs to be achieved regardless of the technological implementation of a quantum computer. Currently, that is the main challenge for all technologies used to build a quantum computer 25 .…”