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Chapter 12 provides an in-depth exploration of pure-state entanglement. It begins with a clear definition of quantum entanglement for pure states, emphasizing its critical role in quantum computing and communication. The chapter highlights various strategies for entanglement manipulation, encompassing deterministic, stochastic, and approximate methods. Quantification of bipartite entanglement is a key focus, with emphasis on entropy of entanglement and the Ky Fan norm-based entanglement monotones. Additionally, the chapter delves into entanglement catalysis and embezzlement of entanglement, presenting them as a nuanced nonintuitive phenomena that underscore the challenges of entanglement preservation during quantum operations. A notable aspect of this chapter is its connection between entanglement theory and the theory of majorization discussed in Chapter 4. Through a comprehensive treatment of these topics, the chapter equips readers with a robust understanding of the intricacies of pure-state entanglement theory.
Chapter 17 delves into quantum thermodynamics, building on the concepts introduced in the resource theory of nonuniformity. This chapter focuses on thermal states and athermality as resources within the quantum domain, emphasizing the significance of Gibbs states and their role in quantum statistical mechanics. It outlines the operational framework for thermal operations, setting the stage for discussions on energy conservation and the second law of thermodynamics in quantum systems. A key aspect of the chapter is the exploration of quasi-classical athermality, illustrating how quantum states deviate from thermal equilibrium when the state of the system commutes with its Hamiltonian. In the fully quantum domain, the chapter introduces closed formulas for quantifying athermality, such as the athermality cost and distillable athermality, both in the single-shot and the asymptotic domains. These measures provide a quantitative understanding of the efficiency of thermal operations and the potential for work extraction or consumption.
This chapter explores how automated legal guidance helps both federal agencies and members of the public. It outlines several specific benefits, including administrative efficiency, communication of complex law in plain language, transparency regarding agency interpretations of the law, internal and external consistency regarding agency communications, and public engagement with the law.
This chapter identifies and explores a central feature of automated legal guidance: “simplexity.” As this chapter introduces this term, simplexity occurs when the government presents clear and simple explanations of the law without highlighting its underlying complexity or reducing this complexity through formal legal changes. Automated legal guidance inherently relies on simplexity as a result of the tension between the complexity of the law and the need of agencies to explain the law in simple terms. In creating the law, the federal government must address complex problems, and it often does so by creating legislation that is replete with errors, ambiguities, and problems. This disconnect between complex federal law and agencies’ need to explain the law to the public in simple and understandable ways forces agencies to rely on simplexity. Automated legal guidance only exacerbates the need for simplexity, because when individuals use automated online tools offered by government agencies, they expect the explanations to be even simpler, more straightforward, and easier to apply than would be the case if they were relying upon written agency publications.
The chapter begins with localizations, including a topological proof of Las Vergnas’s characterization of localizations. Adjoints and their relationship to extensions are discussed. The final part of the chapter discusses intersection properties, particularly on the Euclidean property and non-Euclidean oriented matroids.
Chapter 2 serves as an introduction to the fundamental principles of quantum mechanics, focusing on closed systems. It begins with the historic Stern–Gerlach experiment, highlighting the discovery of quantum spin. The narrative then shifts to the mathematical framework of quantum mechanics, covering inner product spaces, Hilbert spaces, and linear operators. These concepts are crucial for understanding the behavior and manipulation of quantum states, the core of quantum information theory.
The chapter further explores the encoding of information in quantum states, emphasizing qubits, and discusses quantum measurements, revealing the probabilistic nature of quantum mechanics. Additionally, it addresses hidden variable models, offering insights into the deterministic versus probabilistic interpretations of quantum phenomena.
Unitary evolution and the Schrödinger equation are introduced as mechanisms for the time evolution of quantum states, showcasing the deterministic evolution in the absence of measurements. This section underscores the dynamic aspect of quantum systems, pivotal for advancements in quantum information theory.
Chapter 9 introduces the framework of static quantum resource theories, which provide a structured approach for studying different types of quantum resources like entanglement and coherence. The chapter begins by laying out the structure of quantum resource theories, defining what constitutes a quantum resource and how it can be quantified, manipulated, and converted. The text discusses the role of free states and free operations in resource theories, as they form the basis for comparing resources. It introduces state-based resource theories, which focus on the resource content of quantum states, and affine resource theories, which are used to study various interconversions of quantum resources. Resource witnesses, a key concept, are explored as tools to detect the presence of a resource within a quantum state.
Chapter 13 delves into the complex terrain of mixed-state entanglement, extending the discourse from pure-state entanglement to encompass the broader and more practical scenarios encountered in quantum systems. The chapter systematically explores the detection of entanglement in mixed states, introducing criteria and methods such as the Positive Partial Transpose (PPT) criterion and entanglement witnesses, which serve as diagnostic tools for identifying entanglement in a mixed quantum state. Furthermore, it addresses the quantification of entanglement in mixed states, discussing various measures like entanglement cost and distillable entanglement. These concepts highlight the operational aspects of entanglement, including its creation and extraction, within mixed-state frameworks. The chapter also introduces the notion of entanglement conversion distances, providing a quantitative approach to understanding the transformations between different entangled states.
Several analogs to fans and triangulations of point configurations are introduced and motivated as representability issues. The equivalence of some of these analogs is established, while others remain open. Results on the topology of triangulations are proved, most notably for Euclidean oriented matroids.
Photovoltaic (PV) energy grows rapidly and is crucial for the decarbonization of electric systems. However, centralized registries recording the technical characteristics of rooftop PV systems are often missing, making it difficult to monitor this growth accurately. The lack of monitoring could threaten the integration of PV energy into the grid. To avoid this situation, remote sensing of rooftop PV systems using deep learning has emerged as a promising solution. However, existing techniques are not reliable enough to be used by public authorities or transmission system operators (TSOs) to construct up-to-date statistics on the rooftop PV fleet. The lack of reliability comes from deep learning models being sensitive to distribution shifts. This work comprehensively evaluates distribution shifts’ effects on the classification accuracy of deep learning models trained to detect rooftop PV panels on overhead imagery. We construct a benchmark to isolate the sources of distribution shifts and introduce a novel methodology that leverages explainable artificial intelligence (XAI) and decomposition of the input image and model’s decision regarding scales to understand how distribution shifts affect deep learning models. Finally, based on our analysis, we introduce a data augmentation technique designed to improve the robustness of deep learning classifiers under varying acquisition conditions. Our proposed approach outperforms competing methods and can close the gap with more demanding unsupervised domain adaptation methods. We discuss practical recommendations for mapping PV systems using overhead imagery and deep learning models.
This chapter explores how artificial intelligence has enabled the automation of customer service in private industry, such as through online tools that assist customers in purchasing airline tickets, troubleshoot internet outages, and provide personal banking services. Private industry has used machine learning, as well as other forms of artificial intelligence, to develop chatbots and virtual assistants, which can respond to conversational oral or text-based commands. These tools have rapidly become standard customer service vehicles. Recent developments suggest that automated customer service, such as large language models, will become even more sophisticated in the future.
Compliant and safe human–robot interaction is an important requirement in lower limb exoskeleton design. Motivated by this need, this paper presents the design of a compatible lower limb exoskeleton with variable stiffness actuation and anthropomorphic joint mechanisms, for walking assistance and gait rehabilitation. A novel variable stiffness actuator (VSA) based on a guide-bar mechanism was designed, to provide force and impedance controllability. By changing the crank length of the mechanism, the stiffness of the actuator is adjusted in a wide range (from 0 to 1301 Nm/rad), at fast speed (about 2582 Nm/rad/s), and with low-energy cost. These features make it possible for online stiffness adjustment during one gait cycle, to change the human–robot coupling behavior and improve the performance of the exoskeleton. An anthropomorphic hip joint mechanism was designed based on a parallelogram linkage and a passive joint compensation approach, which absorbs misalignment and improves kinematic compatibility between the human and the exoskeleton joint. Furthermore, a torque control-based multimode control strategy, which consists of passive mode, active mode, and hybrid mode, was developed for different disease stages. Finally, the torque control performance of the actuator was verified by benchtop test, and experimental validations of the exoskeleton with a human subject were carried out, which demonstrate that compliant human–robot interaction was achieved, and stiffness variation benefits for control performance improvement when the control mode changes.