Ball-grid array architecture for microfabricated ion traps

TL;DR

This paper introduces a new ball-grid array (BGA) architecture for microfabricated ion traps, enabling more complex designs with improved scalability, and demonstrates its effective performance with calcium and ytterbium ions for quantum computing.

Contribution

The paper presents a novel BGA-based architecture for microfabricated ion traps, reducing trap size and enhancing scalability for quantum information processing.

Findings

Performance comparable to previous traps in ion heating and stability

Successful demonstration of two-qubit entanglement with Yb+ ions

Reduced trap dimensions enable tighter laser focusing for faster operations

Abstract

State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensive surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with $^{40}$Ca$^+$ ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with $^{171}$Yb$^+$ ions in a second BGA trap.