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Fault-tolerant quantum computation with static linear optics

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arXiv 2021年

作者： Tzitrin, Ilan Matsuura, Takaya Alexander, Rafael N. Dauphinais, Guillaume Bourassa, J. Eli Sabapathy, Krishna K. Menicucci, Nicolas C. Dhand, Ish Xanadu TorontoONM5G 2C8 Canada Department of Physics University of Toronto TorontoONM5S 1A7 Canada Department of Applied Physics Graduate School of Engineering University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Centre for Quantum Computation and Communication Technology School of Science RMIT University MelbourneVIC3000 Australia Center for Quantum Information and Control University of New Mexico AlbuquerqueNM87131 United States

The scalability of photonic implementations of fault-tolerant quantum computing based on Gottesman-Kitaev-Preskill (GKP) qubits is injured by the requirements of inline squeezing and reconfigurability of the linear optical network. In this work we propose a topologically error-corrected architecture that does away with these elements at no cost-in fact, at an advantage-to state preparation overheads. Our computer consists of three modules: a 2D array of probabilistic sources of GKP states;a depth-four circuit of static beamsplitters, phase shifters, and short delay lines;and a 2D array of homodyne detectors. The symmetry of our proposed circuit allows us to combine the effects of finite squeezing and uniform photon loss within the noise model, resulting in more comprehensive threshold estimates. These jumps over both architectural and analytical hurdles considerably expedite the construction of a photonic quantum computer. Copyright © 2021, The Authors. All rights reserved.

关键词： Delay circuits

A data-driven Koopman framework for programming the steady state of biological systems with parametric uncertainty

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arXiv 2019年

作者： Hasnain, Aqib Boddupalli, Nibodh Yeung, Enoch Department of Mechanical Engineering University of California Santa Barbara United States Department of Mechanical Engineering Center for Control Dynamical Systems and Computation Biomolecular Science and Engineering University of California Santa Barbara United States

A central challenge in industrial microbiological applications is engineering of genetic networks to achieve a target yield or steady state concentration. This is a particularly challenging problem when optimizing under novel reaction conditions where canonical models of metabolic pathways are no longer valid. In these scenarios, the biological systems are entirely represented by data for which no direct methods exist to optimize the reaction output. We introduce a datadriven model discovery approach that leverages Koopman operator theory and time-series expression measurements to discover models that predict untested reaction outcomes. These Koopman models allow us to design control strategies to achieve target steady state concentrations for products of interest. We develop a model of the trypotophan pathway and illustrate this steady state programming framework on this pathway. Tryptophan is an essential amino acid and is a valuable product in industrial microbiology. We show how Koopman operator theory can thus be used program the steady state of a genetic network in a data-driven context. Copyright © 2019, The Authors. All rights reserved.

关键词： Biological systems

Optimal reporter placement in sparsely measured genetic networks using the Koopman operator

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arXiv 2019年

Optimal sensor placement is an important yet unsolved problem in control theory. In this paper, we make use of the Koopman observability gramian to develop an algorithm for optimal sensor placement of discrete time autonomous nonlinear dynamical systems. The Koopman operator lifts nonlinear dynamics to a higher dimensional space where the dynamics evolve approximately linearly in time. Data in biology are often sampled sparsely in time, therefore a method is developed to compute a temporally fine-grained Koopman operator from the temporally coarse-grained Koopman operator. In the case of noisy data, a closed form expression for the error in the coarse-grained Koopman operator is derived. A novel algorithm for optimal sensor placement is developed for the case of a fixed initial condition. The method is finally demonstrated on a simulation example. Copyright © 2019, The Authors. All rights reserved.

关键词： Nonlinear dynamical systems

The 1995-2018 global evolution of the network of amicable and hostile relations among nation-states

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arXiv 2020年

作者： Askarisichani, Omid Singh, Ambuj K. Bullo, Francesco Friedkin, Noah E. Department of Computer Science University of California Santa BarbaraCA93106 United States Center for Control Dynamical Systems and Computation University of California Santa BarbaraCA93106 United States Department of Mechanical Engineering University of California Santa BarbaraCA93106 United States Department of Sociology University of California Santa BarbaraCA93106 United States

We draw on the data collected by the Integrated Crisis Early Warning System on millions of international and regional public news stories, and this system's indicators of the orientation toward a specific nation-state. We construct the networks of international amicable and hostile relations among nation-states that occur in specific time-periods in order to study the global evolution of the network of such international appraisals. Our analysis presents evidence of an evolution of the structure of this network and a model of the probabilistic micro-dynamics of the alterations of international appraisals during the 1995-2018 span of the available data. Our research provides empirical findings on long-standing debates in the interdisciplinary field of work on Structural Balance Theory. Also remarkably, we find that the trajectory of the Frobenius norm of sequential transition probabilities, which govern the evolution of international appraisals among nations, dramatically stabilizes. Copyright © 2020, The Authors. All rights reserved.

关键词： Convex optimization

Master equations and quantum trajectories for squeezed wave packets

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arXiv 2021年

作者： Gross, Jonathan A. Baragiola, Ben Stace, T.M. Combes, Joshua Center for Quantum Information and Control University of New Mexico AlbuquerqueNM87131-0001 United States Institut Quantique Université de Sherbrooke SherbrookeQCJ1K 2R1 Canada Centre for Quantum Computation & Communication Technology School of Science RMIT University MelbourneVIC3000 Australia ARC Centre for Engineered Quantum System Department of Physics University of Queensland BrisbaneQLD4072 Australia Department of Electrical Computer and Energy Engineering University of Colorado Boulder BoulderCO80309 United States

The interaction between matter and squeezed light has mostly been treated within the approximation that the field correlation time is small. Methods for treating squeezed light with more general correlations currently involve explicitly modeling the systems producing the light. We develop a general purpose input-output theory for a particular form of narrowband squeezed light-a squeezed wave-packet mode-that only cares about the statistics of the squeezed field and the shape of the wave packet. This formalism allows us to derive the input-output relations and the master equation. We also consider detecting the scattered field using photon counting and homodyne measurements which necessitates the derivation of the stochastic master equation. The non Markovian nature of the field manifests itself in the master equation as a coupled hierarchy of equations. We illustrate these with consequences for the decay and resonance fluorescence of two-level atoms in the presence of such fields. Copyright © 2021, The Authors. All rights reserved.

关键词： Wave packets

Locating line and node disturbances in networks of diffusively coupled dynamical agents

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arXiv 2020年

作者： Delabays, Robin Pagnier, Laurent Tyloo, Melvyn Automatic Control Laboratory ETH Zurich ZurichCH-8092 Switzerland Center for Control Dynamical Systems and Computation UCSB Santa BarbaraCA93106-5070 United States Department of Mathematics University of Arizona TucsonAZ85721 United States Department of Quantum Matter Physics University of Geneva GenevaCH-1211 Switzerland School of Engineering University of Applied Sciences of Western Switzerland HES-SO SionCH-1951 Switzerland

A wide variety of natural and human-made systems consist of a large set of dynamical units coupled into a complex structure. Breakdown of such systems can have a dramatic impact, as in the case of neurons in the brain or lines in an electric grid, to name but a few. Preventing such catastrophic events requires in particular to be able to detect and locate the source of disturbances as fast as possible. We propose a simple method to identify and locate disturbances in networks of coupled dynamical agents, relying only on time series measurements and on the knowledge of the (possibly Kron-reduced) network structure. The strength and the appeal of the present approach lies in its simplicity paired with the ability to precisely locate disturbances and even to differentiate between line and node disturbances. If we have access to measurement at only a subset of nodes, our method is still able to identify the location of the disturbance if the disturbed nodes are measured. If not, we manage to identify the region of the network where the disturbance occurs. © 2020, CC BY.

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A concept of a measuring system for probe kinesthetic parameters identification during echocardiography examination

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arXiv 2020年

作者： Winiarski, Tomasz Balsam, Pawel Węgierek, Maciej Borodzicz-Jażdżyk, Sonia Dudek, Wojciech Banachowicz, Konrad Kochanowski, Janusz Marchel, Michal Warsaw University of Technology Institute of Control and Computation Engineering Nowowiejska 15/19 Warsaw00-665 Poland Department of Cardiology Medical University of Warsaw University Clinical Center Banacha 1a Warsaw02-097 Poland Nomagic Sp. z o.o. ul. Rakowiecka 36 Warsaw02-532 Poland

Echocardiography is the most commonly used imaging technique in clinical cardiology. Due to the high demand for this type of examination and the small number of specialists, there is a need to support the examination process through telemedicine. Moreover, specialist training can be supported by appropriate simulation systems. For (i) creating tailor-made tele-echo robots, (ii) creating echo system simulators, and (iii) conducting echo examination with local or remote expert assistance, knowledge about echo probe kinesthetic parameters during echocardiography examination is advisable. The article describes the concept of a measuring system for obtaining such *** Codes J.3 Copyright © 2020, The Authors. All rights reserved.

关键词： Echocardiography

Maximum-matching capture strategies for 3D heterogeneous multiplayer reach-avoid games

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arXiv 2019年

作者： Yan, Rui Duan, Xiaoming Shi, Zongying Zhong, Yisheng Bullo, Francesco Department of Automation Tsinghua University Beijing100084 China Mechanical Engineering Department Center of Control Dynamical Systems and Computation UC Santa BarbaraCA93106-5070 United States

This paper studies a 3D multiplayer reach-avoid game with a goal region and a play region. Multiple pursuers defend the goal region by consecutively capturing multiple evaders in the play region. The players have heterogeneous moving speeds and the pursuers have heterogeneous capture radii. First, we introduce an evasion space (ES) method characterized by a potential function to construct a guaranteed pursuer winning strategy. Then, based on this strategy, we develop conditions to determine whether a pursuit team can guard the goal region against one evader. It is shown that in 3D, if a pursuit team is able to defend the goal region against an evader, then at most three pursuers in the team are necessarily needed. We also compute the value function of the Hamilton-Jacobi-Isaacs (HJI) equation via a convex program and obtain optimal strategies for the players. To capture the maximum number of evaders, we formulate a maximum bipartite matching problem with conflict graph (MBMC). We show that the MBMC is NP-hard and design a polynomial-time constant-factor approximation algorithm to solve it. Finally, we propose a receding horizon strategy for the pursuit team where in each horizon an MBMC is solved and the pursuers adopt the optimal pursuit strategy. We also extend our results to the case of a bounded convex play region where the evaders escape through an exit. Two numerical examples are provided to demonstrate the obtained results. Copyright © 2019, The Authors. All rights reserved.

关键词： Convex optimization

Expertise and confidence explain how social influence evolves along intellective tasks

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arXiv 2020年

作者： Askarisichani, Omid Huang, Elizabeth Y. Sato, Kekoa S. Friedkin, Noah E. Bullo, Francesco Singh, Ambuj K. Department of Computer Science University of California Santa BarbaraCA93106 United States Department of Mechanical Engineering University of California Santa BarbaraCA93106 United States Center for Control Dynamical Systems and Computation University of California Santa BarbaraCA93106 United States Department of Sociology University of California Santa BarbaraCA93106 United States

Discovering the antecedents of individuals’ influence in collaborative environments is an important, practical, and challenging problem. In this paper, we study interpersonal influence in small groups of individuals who collectively execute a sequence of intellective tasks. We observe that along an issue sequence with feedback, individuals with higher expertise and social confidence are accorded higher interpersonal influence. We also observe that low-performing individuals tend to underestimate their high-performing teammate’s expertise. Based on these observations, we introduce three hypotheses and present empirical and theoretical support for their validity. We report empirical evidence on longstanding theories of transactive memory systems, social comparison, and confidence heuristics on the origins of social influence. We propose a cognitive dynamical model inspired by these theories to describe the process by which individuals adjust interpersonal influences over time. We demonstrate the model’s accuracy in predicting individuals’ influence and provide analytical results on its asymptotic behavior for the case with identically performing individuals. Lastly, we propose a novel approach using deep neural networks on a pre-trained text embedding model for predicting the influence of individuals. Using message contents, message times, and individual correctness collected during tasks, we are able to accurately predict individuals’ self-reported influence over time. Extensive experiments verify the accuracy of the proposed models compared to baselines such as structural balance and reflected appraisal model. While the neural networks model is the most accurate, the dynamical model is the most interpretable for influence prediction. Copyright © 2020, The Authors. All rights reserved.

关键词： Forecasting