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Title: Increasing Lifetimes of Superconducting Qubits
Authors: Place, Alexander Patrick McCormick
Advisors: Houck, Andrew A
Contributors: Electrical and Computer Engineering Department
Keywords: qubit
Subjects: Quantum physics
Applied physics
Materials Science
Issue Date: 2022
Publisher: Princeton, NJ : Princeton University
Abstract: Superconducting quantum circuits are a promising platform for quantum computation. The building block for most quantum processors is a qubit (quantum bit) which can store information in a superposition of two states. Superconducting qubits are lithographically defined from metals, often niobium or aluminum. However, these devices have limited use because the information they store decays before most useful computations can take place. In this thesis we explore the cause of these losses. Specifically, we employ tantalum as the capacitor pad of a two-dimensional transmon qubit and find lifetimes and coherence times with dynamical decoupling over 300 us. We then switch to a resonator geometry to probe tantalum materials properties. We develop a power and temperature dependent measurement to quantify sources of decay. We find our resonators are primarily limited by two-level system loss at materials interfaces. Finally we employ this resonator characterization method to determine the effects of processing treatments and new packages onresonator decay, showing a buffered-oxide etch before measurement reduces two-level system loss.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Electrical Engineering

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