Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 288 for “"qubit"”.
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Entangled qubit pairs
… dissertation is to study the kinematics of 2-qubit pairs. A 2-qubit state is specified by the Bloch vectors for each qubit and a 3 × 3 dyadic, representing the expection values of the joint observables. In what follows the main results are listed. • The behaviour of a 2-qubit state under a …
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Qubit dynamics under alternating controls
… designed to extend the duration over which a qubit is a useful computational resource. This is accomplished by control sequences that either retard decoherence, or that accomplish a quantum operation in as short a time as possible. The first problem tackles the use of a composite-pulse control …
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Higher levels of the transmon qubit
… the properties of higher levels in transmon qubit systems. The first part includes a thorough overview of transmon devices, explaining the principles of the device design, the transmon Hamiltonian, and general Circuit Quantum Electrodynamics concepts and methodology. The second part discusses …
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Machine Learning Assisted Superconducting Qubit Readout
… challenges are efficient and high-fidelity multi-qubit control and readout. In particular, qubit-state readout is a significant error source in contemporary superconducting quantum processors. The fidelity of dispersive qubit-state readout depends on the readout pulse shape and frequency as well …
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Optimizing coherence and anharmonicity of superconducting qubit
Quantum computers utilize qubits to store and process quantum information. In superconducting quantum computers, qubits are implemented as quantum superconducting resonant circuits. The circuits are operated only at the two energy states, which form the computational basis for the qubit. To …
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Optimising Qubit Designs for Topological Quantum Computation
… we might optimise the design of topological qubits. The topological operations which are imposed on qubits, in order to perform logic gates for topological quantum computations, are governed by the exchange group of the constituent particles. We examine representations of these exchange …
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Defining, classifying and optimising fermion–qubit mappings
… defining, classifying, and optimising fermion–qubit mappings, a crucial step in simulating fundamental physics on quantum computers. This work surveys the existing catalogue of fermion–qubit mappings, exposing gaps and devising new optimisation routines to aid fermionic simulation through a …
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Quantum signal processing by single-qubit dynamics
… on how even a simple two-level system - the qubit, computes through optimal discrete-time quantum control. Whereas quantum control is typically used to synthesize unitary quantum gates, we solve the synthesis problem of unitary quantum functions with a fully characterization of achievable …
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Digital Readout and Control of a Superconducting Qubit
… the last two decades, and processors with ∼ 50 qubits have been experimentally demonstrated. These systems traditionally utilize microwave frequency control signals, and heterodyne based detection schemes for measurement. Both of these techniques rely heavily on room temperature microwave …
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QUBIT COUPLED MECHANICAL RESONATOR IN AN ELECTROMECHANICAL SYSTEM
… of achieving high quality of superconducting qubit in a high-quality voltage-biased cavity is overcome by integrating a superconducting reflective T-filter to the cavity. Further spectroscopic and pulsed measurements of the hybrid system demonstrate interactions between the ultra-high …
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EFFICIENT APPROACHES FOR QUBIT MAPPING ON NISQ COMPUTERS
… quantum devices. For instance, physical qubit connections are limited, which necessitates the use of quantum SWAP gates to dynamically transform the logical topology during execution. In addition, to optimize fidelity, it is essential to ensure that 1) the allocated hardware has a low …
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Meissner qubit: architecture, characterization and vortex-probing applications
This Dissertation was approved for publication on 2016-04-20 at 12:00.
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Large amplitude driving of a persistent current qubit
In this thesis, the persistent current qubit in the presence of large amplitude microwave radiation is studied. Three main results are presented in this work. A new coherent quasi classical regime has been observed, where coherent quantum dynamics persist even while transitions between energy …
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A superconducting flux QuBit : measurement, noise and control
… series. In this thesis, various aspects of this qubit are studied. It is shown numerically that the qubit behaves as a giant magnetic dipole with quantum tunneling between the two qubit states. The natural coupling between qubits plus the manipulation on a single qubit state provides the building …
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Resonant readout of a superconducting persistent current qubit
… been to increase the coherence times for these qubits. With an objective to reduce the level of readout-induced decoherence, this thesis work focuses on a resonant readout scheme developed for a niobium persistent-current (PC) qubit. This non-dissipative readout approach detects the flux state …
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Engineering Exchange Interaction in Coupled Spin-Qubit Quantum Dots
Made available in DSpace on 2015-09-25T20:09:36Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3337987.pdf: 1801101 bytes, checksum: 570011a5dce77a7cb4211a43262e750e (MD5) Previous issue date: 2008
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Fabrication and measurement of a niobium persistent current qubit
… with superconducting Josephson junction qubits make them prime candidates for the implementation of quantum computing. This doctoral thesis details the study of a niobium Josephson junction circuit for quantum computing applications. The thesis covers two main areas: 1) the fabrication of …
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Pulse Design for Two-Qubit Gates in Superconducting Circuits
… achieving low error rates with superconducting qubits, error-prone two-qubit gates remain a bottleneck in realizing large-scale quantum computers. To boost the two-qubit gate fidelity to the highest attainable levels given limited coherence time, it is essential to develop a systematic framework …
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Towards qubit noise spectroscopy by quantum bang-bang control
… is a method of suppressing decoherence in qubits [VKL99, VL98]. To date, mathematically rigorous treatments of quantum bang-bang control offered little intuition. To complement existing approaches and to seek better understanding, I present intuitive pictures to think about quantum …
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