Quantum Engineering with Mechanical Strain

Abstract

Qubits (quantum bits) have many different physical realizations, each with their own strengths and weaknesses. Futuristic quantum networks will require carefully designed interactions between different types of qubits, much like how modern computing systems utilize different ways of representing classical information. Among these qubits, phonons (quantized mechanical vibrations) are excellent carriers of quantum information in the solid state and could form a “quantum bus” between different types of qubits. Meanwhile, electron spins in solid-state quantum emitters serve as good quantum memories. This dissertation describes an investigation of the interaction between electron spins and mechanical strain in the family of group-IV atomic scale point defects in diamond.

The chapters are presented out of chronological order for the reader’s convenience. We start by using density functional theory to calculate the response of the group IV defects to static mechanical strain. Next, we use electromechanical cantilever devices on diamond to generate static mechanical strain, and experimentally determine the strain response of the germanium vacancy (GeV) defect. Then, we create a coherent phonon drive using surface acoustic devices on diamond, to demonstrate coherent acoustic control of the silicon vacancy (SiV) electron spin. Finally, we utilize this acoustic control scheme to extend the coherence time of the SiV spin, and reveal its interactions with carbon-13 (13 C) nuclear spins in the local environment. By carefully tuning this interaction, we achieve coherent control of a 13 C nuclear spin using acoustic waves.