research

Academic Research

Large arrays of Metal-Oxide Quantum Dots for Electrons-on-Helium

Advisor: Prof. Stephen A. Lyon, Princeton University

Peter Mark Award for "Excellence in Material Science Research", Princeton School of Engineering and Applied Sciences (SEAS).

My senior thesis project focused on the first implementation of quantum dots for electrons-on-helium, to enable ensemble quantum computing and simulation. Since single-electron detection is challenging for electrons-on-helium, our device intended to improve read-out fidelity by simultaneously measuring several quantum dots. I developed nano-fabrication techniques to construct large arrays (~ 10^9) of nearly identical metal-oxide quantum dots. This included extreme fine-tuning of the photolithography and etching steps to ensure uniform shape and depth of the individual dots across the array. I also worked on exact and approximate (Hartree Fock and Constant-Interaction) theoretical models to predict the energy transitions within these many-electron quantum dots.

The size of each dot within these arrays can be varied as per the scientific application. Larger dots (>1um) can be used to simulate atoms by populating them with many electrons, whereas smaller ones (< 100nm) can be used for quantum computing through electron-spin-resonance (ESR) measurements.

Senior Thesis

Dependance of the T1 of Transmon qubits on Readout Drive Power

Advisor: Prof. Alexandre Blais, Université de Sherbrooke

We explored the 'quantum demolition' effects of dispersive readout in circuit QED. Theoretical models predict that qubit relaxation increases with the mean photon number in the associated readout resonator. We compare these models with experimental data from qubits qubits available through the IBM Quantum Experience (IBM Qiskit Pulse) as well through collaboration with experimental groups. Since the research is on-going, some experimental results have been witheld from the final report.

Final Report I: Theory Final Report II: Experiments with Qiskit

New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds

Advisor: Prof. Andrew Houck, Princeton University

We develop a set of nano-fabrication techniques which consistently achieve increased T1 coherence times for Transmon qubits - with an average exceeding 0.30ms, almost three-times the longest T1 previously published (0.114ms). Our recipes eliminating sources of dielectric loss in two ways:

  • Replacing conventional superconductors with tantalum, one with a thin well-controlled oxide.
  • Developing a wet-etch recipe which significantly reduces the carbon impurities and improves surface adhesion on the sapphire substrates.

Nature Communications 12, 1779


Class Projects

Tensor Factorization and Regularized Optimization to Detect Latent Features in fMRI data

Final Project for Mathematics of High Dimensional Data (Graduate Level)

We present a scalable model to represent multi-subject, multi-dataset fMRI data in the same learned latent space. Firstly, we cluster similar subjects based on the tensor decomposition of the input data. Then, we use regularized gradient descent on the data from similar subjects to learn the shared latent space. Our best model consistently achieves accuracies over 85%. Moreover, our chosen regularization ensure scalability and low computational complexity.

Final Paper

Majority Dynamics and Information Aggregation in Social Networks

Final Project for Advanced Algorithm Design (Graduate Level)

We explore time-evolving graphs, where each node's 'opinion' is updated at every time-step to match the majority opinion held by its neighbors. After several time-steps, a winning opinion is declared by performing a majority vote on the population. We provide theory which shows that certain graphs eventually hold a majority incorrect opinion, despite each node being initially biased towards the correct opinion. Furthermore, we empirically investigate the effects of various seeding and opinion-recovery methods.

Final Paper

Transimpedance Amplifiers for High-Speed Fiber Optic Communication

Final Project for Wireless and High-Speed Integrated Circuits and Systems (Graduate Level)

We design a low-noise low-power transimpedence amplifier with a high bandwidth of 7 GHz and gain of over 4.3 kΩ. The design was analytically analyzed using the generalized time-constant method and simulated using Cadence.

Final Paper

Low-Cost Mechanical Ventilator for the COVID-19 Pandemic

Final Project for Robotics and Autonomous Systems

We present a design for a portable mechanical ventilator offering both volume and pressure controlled support, accessible through a clean user-interface. We construct sensors and valves from common hardware and 3D-printed parts, significantly reducing the cost-of-build without sacrificing safety. Our final design costs under $300, which is about one-tenth the cost of off-the-shelf solutions.

Final Paper Pitch Deck

Error Mitigation for Near-Term Quantum Computing

IBM Qiskit Camp and Hackathon

We implemented the Richardson extrapolation technique to reduce gate-errors in noisy intermediate-scale quantum computers, as proposed by Kandala, et. al. 2019 (Nature 567, 491–495).

Presentation Code