Ion-trap Chip Fabrication

Ion-trap-based quantum computers require electrodes to confine ions using electric potential. Additionally, lasers are needed to manipulate the atomic energy levels of ions for quantum operations, which typically require a bulky optical setup.

Both electrodes and optical components can be fabricated at the micro to nanoscale using well-established micro-electro-mechanical system (MEMS) technology. This approach enhances scalability and enables mass production. Many universities and companies, including our chip fabrication team, are actively advancing ion-trap fabrication technology.

Silicon chip fabrication

Our chip fabrication team specializes in designing and fabricating ion-trap chips on silicon substrates using MEMS fabrication techniques. The fundamental architecture of our ion-trap chips consists of a layered structure: ground plane, insulating oxide layer, and precisely patterned control electrodes. To advance the performance metrics of these ion-trap chips, we are actively optimizing various fabrication processes. Our research efforts are concentrated on implementing innovative solutions to enhance trap stability, reduce heating rates, and improve operational fidelity.

Multi-metal layer

Our chip fabrication team is creating a new ion trap chip design that uses multiple layers of metal - with the top layer dedicated to electrodes that interact with ions, and separate lower layers used for wiring connections. This architecture is crucial for implementing segmented DC control electrodes in ion traps, enabling numerous independently addressable electrodes without compromising the trapping region.

Our key objectives include optimizing interlayer connections, refining planarization techniques, and implementing advanced routing strategies to minimize crosstalk. These advancements will support next-generation ion-trap architectures, enabling larger ion arrays with enhanced control precision.

Overhang structure

To mitigate dielectric charging effects, we've implemented a strategic design where ions are shielded from direct exposure to dielectric surfaces. The top control electrodes are intentionally fabricated with dimensions that extend beyond the underlying oxide layer, creating an overhang structure. We are currently incorporating this overhang technique into our production-level ion-trap chip fabrication process, demonstrating promising improvements in trap stability and coherence times.

Comb drive

The comb drive is a MEMS-based actuator that has been widely used in a variety of applications, such as sensors and optical switches, thanks to its simple structure and ease of fabrication. Our research team is developing a 3-axis actuator based on the comb drive, which is a key component for miniaturizing a fiber cavity integrated with a trapped ion system. This concept was initially proposed in the following reference [1]. By realizing this system, we will establish a more scalable and integrated fiber cavity system.

Integrated photonics

One of the main projects of our chip fabrication team is the integration of optical components directly within our ion-trap chips. We are collaborating with another university group (Kookmin University, SNU Convergence) on this research project. Our interests include simulation, fabrication technology development, and material science for integrating optical components.

Integrated optical components

Our current research efforts are concentrated on developing and optimizing fundamental photonic components, with particular emphasis on waveguides and grating couplers. We are systematically refining nanoscale fabrication protocols through the implementation of advanced electron-beam lithography techniques. This precision engineering at the nanometer scale enables us to achieve the high-fidelity structures necessary for efficient light delivery and coupling in integrated quantum systems.

Transparent conductive oxide (TCO)

We are investigating transparent conductive oxide (TCO) films as optical windows for ion-trap systems. These advanced materials simultaneously provide electrical conductivity and optical transparency—a critical combination that enables efficient light delivery while maintaining electrical characteristics necessary to shield ions from charging effects. Our comprehensive approach includes optimization of TCO film transparency through refined fabrication techniques, supported by theoretical calculations and detailed simulations to validate performance parameters.

References

[1] Lee, Moonjoo, et al. "Microelectromechanical-system-based design of a high-finesse fiber cavity integrated with an ion trap." Physical Review Applied 12.4 (2019): 044052.

Google Sites

Report abuse