Research

Optical tweezer control for neutral-atom quantum computation

Mentors: Prof. Jeff Thompson, Dr. Bichen Zhang

Optical tweezer arrays are powerful tools for quantum information science, especially when trapping neutral Rydberg atom qubits. These arrays are generally generated by two $n-$ and $m-$tone acousto-optical deflectors, allowing for tight, replicable optical foci. However, these systems lack individual control over sites, and suffer from limited geometries. In this project, I designed a tweezer array generator using a spatial light modulator and digital micromirror device. Phase estimation was done with a modified version of the Gerchberg-Saxton algorithm, and computer vision methods were employed to process, calibrate, and control these tweezer grids at high speed. Tests showed that this system was highly scalable, able to generate up to 104 tweezer sites, switch 4900 sites, and image 1419 sites at once. The system also achieved switching speeds of ~50 kHz, with contrast ratios of above 104, giving a Rabi frequency ratio bound of $<10^{-2}$. Future work includes camera-based phase estimation, improvements in SLM Gaussian beam generation, and large-scale XZZX surface code addressing.

Computational optimization for sympathetic cooling of trapped ions

Mentors: Prof. Crystal Noel, Prof. Chris Monroe, Dr. Or Katz

Entangling gates like Mølmer-Sorensen gates utilize the motional degree of freedom of these ions, while misalignment can lead to local gradients in Rabi frequency, underscoring the importance of reducing ion motion. However, because cooling is a decoherent process, ion chains are cooled sympathetically; i.e., particular ions are designated as coolants and are used for laser cooling, reducing the motion of the qubit ions through the Coulomb interaction. However, best practices for sympathetic cooling have not been found yet. This study aims to use computational simulation and analysis techniques in order to shed some light on best practices for sympathetic cooling, such as coolant placement, cooling duty cycle, and number of gates per cooling cycle.