Vertical ion transport in a surface Paul trap: escalator and elevator approaches

TL;DR

This paper introduces two methods, escalator and elevator, for vertical ion transport in surface Paul traps, enabling nearly double the ion confinement height for enhanced quantum processing capabilities.

Contribution

It presents the design and analysis of novel escalator and elevator approaches for vertical ion transport in surface ion traps, expanding ion manipulation techniques.

Findings

Both approaches achieve nearly a twofold increase in ion confinement height.

The escalator is a geometrically optimized transition between trapping zones.

Two elevator configurations dynamically reposition the RF null for vertical transport.

Abstract

Surface ion traps confining and manipulating tens of ion qubits have become the leading platform for quantum processors with high quantum volume. These devices employ the Quantum Charge-Coupled Device (QCCD) architecture, wherein multiple trapping zones are linked by an on-chip transport network that shuttles ion chains, enabling full connectivity through physical ion transport in a plane parallel to the chip surface. The ability to move ions perpendicular to this plane can offer additional advantages, including tuning the laser-ion interaction strength, systematic studies of surface-induced heating mechanisms, and precise alignment with a mode of an external optical cavity. We introduce an "escalator" - a geometrically optimized transition between trapping zones of different confinement heights - and present a comparative analysis of two "elevator" configurations that reposition the RF null dynamically via additional electrode voltages. Both approaches enable nearly a twofold change in the ion confinement height above the chip surface.