Prethermal Strong Zero Modes and Topological Qubits

We prove that quantum information encoded in some topological excitations, including certain Majorana zero modes, is protected in closed systems for a time scale exponentially long in system parameters. This protection holds even at infinite temperature. At lower temperatures the decay time becomes even longer, with a temperature dependence controlled by an effective gap that is parametrically larger than the actual energy gap of the system. This non-equilibrium dynamical phenomenon is a form of prethermalization, and occurs because of obstructions to the equilibriation of edge or defect degrees of freedom with the bulk. We analyze the ramifications for ordered and topological phases in one, two, and three dimensions, with examples including Majorana and parafermionic zero modes in interacting spin chains. Our results are based on a non-perturbative analysis valid in any dimension, and they are illustrated by numerical simulations in one dimension. We discuss the implications for experiments on quantum-dot chains tuned into a regime supporting end Majorana zero modes, and on trapped ion chains.Comment: 20 pages. v2: reorganized and added overview sectio

Entanglements of Modernity, Colonialism and Genocide: Burundi and Rwanda in Historical-Sociological Perspective

This thesis explores two lines of critique of social theories of modernity by way of a historical sociological analysis of Burundi and Rwanda. Firstly, it engages with arguments about the Euro-/Western-centric assumptions which are suggested to have underpinned many conceptualisations of modernity. Secondly, it considers the notion that the processes of modernity move gradually, if precariously, towards more peaceable forms of cohabitation within and between societies. In doing so, it draws on and develops the theoretical framework of entanglement, which emphasises the existence of a variety of intertwined historical routes to and through modernity. Central to the analysis is a critique of both the idea that modernity entails a progressive ‘detraditionalisation’ or destruction of traditional societal forms, and the idea that tradition provides a repository of cultural resources upon which are founded distinct, plural ‘modernities’. In the case of Burundi and Rwanda, I argue that colonial modernity, in its indirect rule format, in important respects ‘solidified’ tradition in racial terms. In the transition to independence, the colonial legacy both enabled and delimited autonomous societal self-understandings and political movements. In the postcolonial period, the tension between the modern commitment to autonomy on the one hand and seemingly traditional legacies on the other has been realised in profoundly destructive and violent ways. I conclude that the historical experiences of extremely violent social conflict in Burundi and Rwanda are situated within a specific route to and through modernity. The original contribution of the thesis is twofold. Firstly, it presents a new substantive case study to the analysis of non-Western experiences and interpretations of modernity. Secondly, in doing so, it offers a theoretical contribution to debates concerning the multiplicity of modernity which have arisen principally in the paradigm of ‘multiple modernities’ and postcolonial sociology

Entanglements of Modernity, Colonialism and Genocide: Burundi and Rwanda in Historical-Sociological Perspective

This thesis explores two lines of critique of social theories of modernity by way of a historical sociological analysis of Burundi and Rwanda. Firstly, it engages with arguments about the Euro-/Western-centric assumptions which are suggested to have underpinned many conceptualisations of modernity. Secondly, it considers the notion that the processes of modernity move gradually, if precariously, towards more peaceable forms of cohabitation within and between societies. In doing so, it draws on and develops the theoretical framework of entanglement, which emphasises the existence of a variety of intertwined historical routes to and through modernity. Central to the analysis is a critique of both the idea that modernity entails a progressive ‘detraditionalisation’ or destruction of traditional societal forms, and the idea that tradition provides a repository of cultural resources upon which are founded distinct, plural ‘modernities’. In the case of Burundi and Rwanda, I argue that colonial modernity, in its indirect rule format, in important respects ‘solidified’ tradition in racial terms. In the transition to independence, the colonial legacy both enabled and delimited autonomous societal self-understandings and political movements. In the postcolonial period, the tension between the modern commitment to autonomy on the one hand and seemingly traditional legacies on the other has been realised in profoundly destructive and violent ways. I conclude that the historical experiences of extremely violent social conflict in Burundi and Rwanda are situated within a specific route to and through modernity. The original contribution of the thesis is twofold. Firstly, it presents a new substantive case study to the analysis of non-Western experiences and interpretations of modernity. Secondly, in doing so, it offers a theoretical contribution to debates concerning the multiplicity of modernity which have arisen principally in the paradigm of ‘multiple modernities’ and postcolonial sociology

System-Level Testing of the Advanced Stirling Radioisotope Generator Engineering Hardware

To support future NASA deep space missions, a radioisotope power system utilizing Stirling power conversion technology was under development. This development effort was performed under the joint sponsorship of the Department of Energy and NASA, until its termination at the end of 2013 due to budget constraints. The higher conversion efficiency of the Stirling cycle compared with that of the Radioisotope Thermoelectric Generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, Pluto New Horizons and Mars Science Laboratory) offers the advantage of a four-fold reduction in Pu-238 fuel, thereby extending its limited domestic supply. As part of closeout activities, system-level testing of flight-like Advanced Stirling Convertors (ASCs) with a flight-like ASC Controller Unit (ACU) was performed in February 2014. This hardware is the most representative of the flight design tested to date. The test fully demonstrates the following ACU and system functionality: system startup; ASC control and operation at nominal and worst-case operating conditions; power rectification; DC output power management throughout nominal and out-of-range host voltage levels; ACU fault management, and system command / telemetry via MIL-STD 1553 bus. This testing shows the viability of such a system for future deep space missions and bolsters confidence in the maturity of the flight design

Learning Input Constrained Control Barrier Functions for Guaranteed Safety of Car-Like Robots

We propose a design method for a robust safety filter based on Input Constrained Control Barrier Functions (ICCBF) for car-like robots moving in complex environments. A robust ICCBF that can be efficiently implemented is obtained by learning a smooth function of the environment using Support Vector Machine regression. The method takes into account steering constraints and is validated in simulation and a real experiment

Resourceful program synthesis from graded linear types

Linear types provide a way to constrain programs by specifying that some values must be used exactly once. Recent work on graded modal types augments and refines this notion, enabling fine-grained, quantitative specification of data use in programs. The information provided by graded modal types appears to be useful for type-directed program synthesis, where these additional constraints can be used to prune the search space of candidate programs. We explore one of the major implementation challenges of a synthesis algorithm in this setting: how does the synthesis algorithm efficiently ensure that resource constraints are satisfied throughout program generation? We provide two solutions to this resource management problem, adapting Hodas and Miller’s input-output model of linear context management to a graded modal linear type theory. We evaluate the performance of both approaches via their implementation as a program synthesis tool for the programming language Granule, which provides linear and graded modal typing

Story Telling and Truth-Telling: Personal Reflections on the Native American Experience in Law Schools

In January of 2021, the American Association of Law Schools (“AALS”) theme was Freedom, Equality and the Common Good. The Indian Nations and Indigenous Peoples Section of the AALS embraced the theme and announced a call for personal reflections incorporating the experiences of Native Americans in law schools. The theme of striving for academic freedom and equality allows for an in-depth questioning of whether Native Americans have been adequately and appropriately represented in legal curricula in the nation’s approximately two hundred law schools. The aspirational goal of realizing the common good must be inclusive of Native American voices as students, faculty, staff, and graduates and in curricula choices in law schools across the country. There has been sparse legal scholarship on the experience of Native American applicants, law students, faculty, and staff in law schools. The Indigenous perspective essays in this compilation are an opportunity to hear the voices of Indigenous peoples on their lived experiences in seeking law degrees and careers in law-related fields. Words such as resiliency, endurance, and perseverance often come to mind when Native Americans discuss their personal experiences in the legal academy. The following collection of essays are a contribution to the legal academy in the Indigenous tradition of storytelling shared as firsthand accounts through the seven authors’ perspectives. Within the personal reflections, the tenacity of Native people to succeed and overcome barriers is a common theme. Many of the contributors speak to the value of mentoring or becoming a Native lawyer to serve as a mentor. The compilation provides insight into the experience the authors share of a deep commitment to their Indigenous communities and to trailblazing for the next generation of Native lawyers