Computational Modelling of Superconducting Quantum Interference Devices
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Date
2022
Authors
Kong, Thomas Xing-Da
Editors
Advisors
Tettamanzi, Giuseppe Carlo
Fumeaux, Christophe
Fumeaux, Christophe
Journal Title
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Thesis
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Abstract
Superconducting quantum interference devices (SQUIDs) are state-of-the-art magnetic
flux-to-voltage transducers with a plethora of applications spanning ultra-high
precision magnetometry, medical imaging, remote sensing and quantum metrology.
Several figures-of-merit have been devised to assess the performance of a SQUID for
sensing applications. These descriptors allow for an objective ranking of the sensing
capabilities of different devices. An open problem in the discipline is concerned
with the optimisation of SQUIDs relative to these performance criteria. While the
optimisation process could be carried out via an iterative cycle of design, fabrication
and measurement, where the results yielded from one set of devices serves to inform
future designs, this process is time-consuming and cost-prohibitive. An alternative
method is to develop a mathematical model that is able to accurately describe the
behaviour of SQUIDs and perform the optimisation process computationally using
the wealth of available global optimisation algorithms.
The goal of this research is to develop a core framework that is capable of modelling
an arbitrary superconducting device, using the specified design parameters of
the device together with relevant material parameters as inputs to the model. This
work builds upon existing models in the field, based upon a lumped element circuit
model together with elementary superconducting theory. The model is capable
of simulating noise, capacitive effects, temperature dependent parameter variation,
asymmetry in the device, and also possesses the capacity to directly compute the
loop inductances from the device geometry. The intention is to create a realistic
model that is both lightweight and predictive, so that it is amenable for use
in the computational search for an optimal device design. We validate our model
by applying it to the direct current (DC) SQUID and the one-dimensional parallel
superconducting quantum interference filter (SQIF), for which there are prior
studies and experimental data available for comparison. We also perform an initial
exploratory investigation of the influence of each of the device parameters on the
characteristic behaviour of the SQUID and begin to place bounds on the region of
parameter space in which the device is operating under a desirable regime, so as to
restrict the regions that should be searched more intensively for an optimal configuration.
The outcomes of this project will form the foundation of the design process
of real superconducting devices to be carried out with supercomputing facilities, and
will lead to future collaborations with foundries such as SEEQC where the model
may be used to inform the development and fabrication of new, more performant
devices.
School/Discipline
School of Physics
Dissertation Note
Thesis (M.Phil.) -- University of Adelaide, School of Physics, 2022
Provenance
This thesis is currently under embargo and not available.