Senior Engineering Thesis Capstone Project

In my last undergraduate year, I completed a substantial research and design project, where I learned about an entirely new field, fabricated a micro-scale device and developed a control system to operate it. The project received the following awards:

• Harvard SEAS Dean’s Award for the Outstanding Project in Electrical Engineering. Given to the best project within electrical engineering. (News article about the award)

• Harvard Hoopes Prize. This is the highest award given by Harvard for “recognizing, promoting, honoring, and rewarding excellence.” The award is given to 80 undergraduates per year. The project was the only engineering thesis awarded the prize. More information about the award is available on the Hoopes Prize website and this Harvard Crimson article.

• Harvard Kirkland House Science Award. This prize is awarded to a graduating senior in Kirkland House who has excelled in the field of chemistry, physics, engineering, computer science, or other physical or mathematical science.

Surface Acoustic Waves (SAWs) are longitudinal waves that travel across the surface of a material. Their unique generation and propagation properties have resulted in SAW-enabled devices finding use in many current applications, like mobile phone radios. They have also found recent use in coupling two-level quantum systems in quantum computing. These devices are passive and thus still present challenges to their broader application. The physical features of a device define the use case for the design, which cannot change dynamically. This means that existing SAW devices are unable to meet the demands of evolving telecommunication standards and to drive the states of isolated two-level quantum systems.

Active devices with the ability to change the properties of SAWs in transit overcome these challenges. This project demonstrates electrically-controlled in-transit SAW amplitude modulation with a dynamic range of 4 dB, and phase modulation of 180° through simulations and fabricated prototype devices. This achievement paves the way for enabling smaller, higher bandwidth and higher bitrate communication systems, ushering in multi-gigabit-class wireless protocols. It also brings us one step closer to realising commercial quantum computing, by being able to leverage the benefits of different quantum systems for quantum error correction schemes and larger qubit architectures.

Harvard SEAS featured the project on its website, found here.

The citation for the thesis is:

Weninger, Nicolas. 2020. Electro-Acoustic Modulation of Surface Acoustic Waves on Thin-Film Lithium Niobate Substrate. Bachelor's thesis, Harvard John A. Paulson School of Engineering and Applied Science. http://nrs.harvard.edu/urn-3:HUL.InstRepos:42665426