Design and control of microfabricated ion traps for quantum computing

Matthew Day

Daniel Lobser

Michael Pfeifer, Marco Valentini, Matthias Dietl +7 more

Microfabricated ion trap chips are at the core of some of the most advanced quantum computers. How a large number of ions is arranged and controlled on an ion trap chip depends on the chosen trap architecture. One such architecture is the quantum spring array (QSA). In the QSA architecture, ion chains are arranged in a two-dimensional lattice and interact with ion chains in neighboring sites in the radial and axial directions of the respective chain. This interaction, or coupling, is mediated by the Coulomb force while keeping ions in separate trapping sites, and scales inversely with the third power of the separation. The capability to control the distance between ions in the lattice is thus essential. In previous works, the radial separation between ions was tuned by controlling the rf pseudo-potential, which revealed to be experimentally challenging to realize while maintaining low heating rates. In this work, we present an ion trap chip design that allows tuning of the radial distance between ions using only dc voltages. The radial transport is executed between different interaction zones, designated for quantum operations, through specifically designed transition zones. A prototype of this type of ion trap chip was microfabricated on fused silica substrate. Its functionality is characterized by demonstrating dc-controlled radial transport of a single ion through a transition zone and measuring stray fields and ion heating rates in the center of the trap. Moreover, the fabrication of a multi-metal layer version of such a trap is presented as a scaling path for the presented chip design.

Nila Krishnakumar, F. J. Giebel, Eike Iseke +8 more

Multilayer surface-electrode ion traps provide a scalable platform for quantum processors. In this paper we present a demonstrator chip designed to implement an 8-qubit shuttling-based quantum processor with chip-integrated microwave control for quantum gates. The design is based on a linear Paul trap geometry. All-to-all connectivity will be implemented through ion swapping. The production of the trap chip is carried out with multistep microfabrication. The 2-layer ion trap chip with two storage registers and an interaction zone has a size of 5 mm x 10 mm . Flexibility in signal routing is improved through the use of thick and planarised metal–dielectric layers. • Fabrication of multilayer asymmetric ion trap chip aiming to enable an 8-qubit quantum computer. • Brief insight into the linear trap chip design with quantum charged-coupled device architecture. • Wafer level multistep microfabrication procedure of the chip production. • Chip characterisation with respect to the target design features and trapping readiness.

Clark Highstrete, Matthew G. Blain, Kevin Fortier +8 more

Peter Maunz, Raymond A. Haltli, Andrew E Hollowell +7 more