160 research outputs found
Sharp Page transitions in generic Hamiltonian dynamics
No full textNational Science Foundation http://dx.doi.org/10.13039/100000001Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Kavli Institute for Theoretical Physics, University of California, Santa Barbara http://dx.doi.org/10.13039/10000595
Simulation data and codes for "Stabilizing Non-Abelian Topological Order Against Heralded Noise via Local Lindbladian Dynamics"
No full textThe repository includes Python code files and the data plotted in the figures in npz format. The function modules are included in the src directory. The codes for running the main scripts and plotting scripts are included in the results directory. The code is organized into three different models: d4_stabilizers, d4_flags, and toric_code. The data is provided in the compressed zip file. The details of the Python environment are in the "create_pyenv.yaml" file. The details can be found in the README file.In this project, we show how active measurement and local feedback can be used to stabilize both Abelian and non-Abelian mixed-state topological order in two spatial dimensions. We show that this topological order is robust against the presence of the finite-strength "heralded" noise. We computationally approach this problem by developing a generalized version of the stabilizer tableau formalism that permits efficient simulation of the non-Abelian Lindbladian dynamics. Here we present the detailed numerical procedures used to establish these results.NSF DMR-2313858 (SC and FJB)Institute for Robust Quantum Simulation (RQS) seed grant (SG)Sivian Fund and the Paul Dirac Fund at the Institute for Advanced Study (AP)U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0009988 (AP)Chirame, Sanket; Prem, Abhinav; Gopalakrishnan, Sarang; Burnell, Fiona J.. (2025). Simulation data and codes for "Stabilizing Non-Abelian Topological Order Against Heralded Noise via Local Lindbladian Dynamics". Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/cmbb-n777
Compressing and Predicting Quantum Dynamical Systems
No full textIn this thesis I approach the problem of developing a probabilistic model to compress and learn quantum dynamical systems. Recent literature has demonstrated that for practical purposes a quantum process can be expressed efficiently through its classical shadow, which is generated by repeatedly measuring the state of a qubit before and after a quantum evolution. Given this result, quantum dynamics can be represented by the evolution of classical shadows, which form a stochastic process on a discrete probability space. In this thesis I constructed a dimensionality reduction framework based on mutual information maximization to compress and learn stochastic processes from data. After constructing variational lower bounds for mutual information, I adapt techniques from machine learning to find tractable and expressive parameterizations for my probabilistic models. To develop and test the dimensionality reduction process, I first worked with a simpler stochastic process---the symmetric exclusion process (SEP). Once I verified my dimensionality reduction framework on SEP, I simulated a quantum Brickwork circuit with U(1) symmetry and computed its classical shadows to generate a discrete stochastic process. I then tested my dimensionality reduction framework to see if it could adequately learn the quantum dynamics. I find that for both the SEP and Brickwork processes my model learns coarse-grained features of the process state-space which is consistent with the diffusive nature of both processes: coarse-grained features are preserved during process evolution unlike high-frequency features
Crystalline and glassy states of ultracold atomic systems
Get PDF"Spatially modulated ordered states, such as crystals, liquid crystals, and antiferromagnets, are ubiquitous in nature but relatively difficult to realize in ultracold atomic systems. In the present work, we present a scheme for generating controllable cavity-mediated interactions between atoms, and show that these interactions give rise to a crystallization transition in the case of a transversely pumped optical cavity. We focus on the case of multimode cavities, in which the interactions are relatively local and the range of possible ordered configurations (and consequently of low-energy fluctuations) is large; as we show, the crystallization transition for a Bose-Einstein condensate in a multimode cavity is driven first-order by fluctuations, through the Brazovskii effect. The ordered state to which this crystallization transition gives rise is a ""supersolid,"" possessing both superfluid and solid order. We address the crystallization transition and the properties of the ordered state, discuss the experimental feasibility of observing these, and finally show how ordering in layered systems of atoms is geometrically frustrated. We then introduce a more straightforward realization of frustrated cavity-mediated interactions, viz. systems of randomly-positioned spins in multimode cavities. We show by means of a mapping to a variant of the Hopfield associative-memory model that such systems exhibit a spin-glass phase. Finally, we consider a different ultracold-atomic setting---that of spin-orbit-coupled Bose gases---in which the Brazovskii effect has a profound influence on the low-temperature phases, leading to a universal preference for stripe-like ordering at zero temperature and bosonic pair condensation at nonzero temperatures."Item withdrawn by Mark Zulauf ([email protected]) on 2012-06-08T15:52:03Z
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University of Illinois Theses & Dissertations (ID: 1)
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Penerapan Forecasting Methods Untuk Meningkatkan Strategi Dalam Sistem Penjualan Ponsel Pada Sarang Cell Semarang
No full textSales is a major factor in supporting the survival of a company. Therefore, companies must be able to determine policies related to sales activities undertaken by the company. To address the issue of sales to match the target company, it is necessary to have a sales forecasting. One of the methods that can be used is forecasting. Sarang Cell are located in Semarang Banyumanik is a company that sells various brands of mobile phones. Unfortunately in the process of selling its products, Sarang Cell not equipped with a sales forecasting. To overcome the problem of the system is needed that can predict the number of sales per-monthly to the management of sales data over regular phone. In this case the author uses forecasting methods forecasting. This method is used to calculate the short-term forecasting. Background With the latter, the authors are interested to make the study with the title "Application of Forecasting Methods To Boost Mobile Strategy In Sales System In Sarang Cell Semarang"
Wages distribution system of sailors in Sarang : John Rawls’s theory of justice perspective
No full textThe sailor community is one of the components that fall into the category of coastal communities. The mentioning of fishermen associated with the profession of fishing at sea. In the other words, the fishermen are the ones who make a living from the sea directly related to fishing. People made the sea as a source of livelihood especially those related to fishing, called as fishermen, regardless of variations available equipments.
This research focus on wages distribution system of sailor in Sarang. The writer try to analyze this system using the theory of justice by John Rawls. In choosing theory of justice by John rawls is based on consideration that this theory appropriate with these problems. From this, the researcher moved to conduct this research that could later contribute new ideas over a system that is more directed to the justice and welfare. Based on the background of the issues mentioned above, there are several problems that can be formulated by author such us: firstly, how is the system of wages distribution used by sailors of Sarang? And secondly, how is this system analyzed using John Rawls’s Theory of Justice?
This study uses a qualitative approach. That is the assessment of the research problem will generate descriptive data, or in other word, this study prefers descriptive data collection as outlined in the form of report and description. A qualitative approach was considered appropriate to study the problems in this case, because of the things that were observed directly related to the actual problems faced today.
After doing research, explaining and analyzing in previous chapters, it can be concluded that: First, Generally, wages distribution practice that occurred in Sarang is the result 100% of haul that had been sold in TPI will be decreased by supplies cost and LW cost first. Then will be divided become two parts, 50% for Majikan, and 50% for ABK. Among the ABK, the 50% then will be divided again by one condition, which is divided by 25 parts then it is added with 9 parts. Writer found Majikan exploitation from prevailing LW system. Based on data from LW system that prevailed in fishing communities Sarang, then the employer is one who obtained a huge advantage as ship owner. Employers will be more fortunate, while the ABK would be miserable. Second, after analyze the problem with point of view by John Rawls’s Theory of Justice, the writer states that ABK Sailors like being in a veil called ignorance or without knowledge. Sarang Sailors feel alienated from the system that prevailed by the employer, ranging from wages distribution procedure, until cost of supplies and also there are many exploitation by Majikan towards ABK
Many body localized systems weakly coupled to baths
No full textWe consider what happens when a many body localized system is coupled to a heat bath. Unlike previous works, we do not restrict ourselves to the limit where the bath is large and effectively Markovian, nor to the limit where back action on the bath is negligible. We identify limits where the effect of the bath can be captured by classical noise, and limits where it cannot. We also identify limits in which the bath delocalizes the system, as well as limits in which the system localizes the bath. Using general arguments and dimensional analysis, we constrain the overall phase diagram of the coupled system and bath. Our analysis incorporates all the previously discussed regimes, and also uncovers a new intrinsically quantum regime that has not hitherto been discussed. We discuss baths that are themselves near a localization transition, or are strongly disordered but protected against localization by symmetry or topology. We also discuss situations where the system and bath have different dimensionality (the case of ‘boundary MBL’ and ‘boundary baths’)
Nonlinear spectroscopy of random quantum magnets
Get PDFWe study nonlinear response in quantum spin systems near infinite-randomness critical points. Nonlinear dynamical probes, such as two-dimensional (2D) coherent spectroscopy, can diagnose the
nearly localized character of excitations in such systems. We present exact results for nonlinear response in the 1D random transverse-field Ising model, from which we extract information about critical behavior that is absent in linear response. Our analysis yields exact scaling forms for the distribution functions of relaxation times that result from realistic channels for dissipation in random magnets. We argue that our results capture the scaling of relaxation times and nonlinear response in generic random quantum magnets in any spatial dimension
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