Repository logo
 

Expansibility Evaluation of a Two-dimensional Access Array for Quantum Computing


Loading...
Thumbnail Image

Type

Thesis

Change log

Authors

Michniewicz, John 

Abstract

The main challenge in quantum computing is not how to make qubits, but how to make a lot of them. Especially, the one-qubit-one-input approach is unsustainable for higher numbers. This issue has already been resolved in classical computing, and I investigate a similar solution for quantum. I evaluate the expansibility prospects of a multiplexing chip: a two-dimensional access array, designed to combat this very problem. First, I characterize on-chip integrated transistors. I list their standard transport parameters, such as threshold voltage, subthreshold swing, and drain induced barrier lowering. Additionally, I report Coulomb oscillations and the formation of quantum dots in 40 nm commercially-available MOSFET devices. I benchmark those against a finFET of the same dimensions, designed for quantum operation. I reflect on the readiness of industrial CMOS devices for use in quantum computing. Then, I assess the operation of control transistors in a memory cell structure. I analyze retention times and comment on their usability for a refresh mechanism and time-multiplexed access to quantum information. Afterward, I demonstrate the mechanism of gate-based reflectometry readout. I detail the RF circuitry, including the room-temperature equipment, and the on-chip analog LC resonators. I present my findings on tuning individual parameters, and their impact on the signal quality, quantitatively depicted by the signal-to-noise ratio and Q factor comparison. I explain the difficulties faced with managing the readout at several GHz, and some other challenges, including parasitics-induced frequency shift and overlap. Finally, I demonstrate time- and frequency-domain multiplexing for an integrated array, as well as two different cointegrated architectures.

Description

Date

2021-12-24

Advisors

Ciccarelli, Chiara

Keywords

quantum, quantum computing, spinqubits, silicon, reflectometry, gate-based sensing, qubit, qubits, quantum dot, multiplexing, FDM, TDM

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge

Collections