One-dimensional many-body entangled open quantum systems with tensor network methods

We present a collection of methods to simulate entangled dynamics of open quantum systems governed by the Lindblad equation with tensor network methods. Tensor network methods using matrix product states have been proven very useful to simulate many-body quantum systems and have driven many innovations in research. Since the matrix product state design is tailored for closed one-dimensional systems governed by the Schr\"odinger equation, the next step for many-body quantum dynamics is the simulation of open quantum systems. We review the three dominant approaches to the simulation of open quantum systems via the Lindblad master equation: quantum trajectories, matrix product density operators, and locally purified tensor networks. Selected examples guide possible applications of the methods and serve moreover as a benchmark between the techniques. These examples include the finite temperature states of the transverse quantum Ising model, the dynamics of an exciton traveling under the influence of spontaneous emission and dephasing, and a double-well potential simulated with the Bose-Hubbard model including dephasing. We analyze which approach is favorable leading to the conclusion that a complete set of all three methods is most beneficial, push- ing the limits of different scenarios. The convergence studies using analytical results for macroscopic variables and exact diagonalization methods as comparison, show, for example, that matrix product density operators are favorable for the exciton problem in our study. All three methods access the same library, i.e., the software package Open Source Matrix Product States, allowing us to have a meaningful comparison between the approaches based on the selected examples. For example, tensor operations are accessed from the same subroutines and with the same optimization eliminating one possible bias in a comparison of such numerical methods.Comment: 24 pages, 8 figures. Small extension of time evolution section and moving quantum simulators to introduction in comparison to v

mSpace meets EPrints: a Case Study in Creating Dynamic Digital Collections

In this case study we look at issues involved in (a) generating dynamic digital libraries that are on a particular topic but span heterogeneous collections at distinct sites, (b) supplementing the artefacts in that collection with additional information available either from databases at the artefact's home or from the Web at large, and (c) providing an interaction paradigm that will support effective exploration of this new resource. We describe how we used two available frameworks, mSpace and EPrints to support this kind of collection building. The result of the study is a set of recommendations to improve the connectivity of remote resources both to one another and to related Web resources, and that will also reduce problems like co-referencing in order to enable the creation of new collections on demand

Two Laboratory Studies of People\u27s Responses to Sonic Booms and Other Transient Sounds as Heard Indoors

Manufacturers of business jets have expressed interest in designing and buildin

The Effectiveness of Collaboration Within Supply Chain Management: A Case Study of Adidas Group

For a multi-national company like Adidas, supply chain management is one of the most crucial aspects of business operations. Products cannot be sold unless Adidas’s supply chain is well-managed and efficient, and public perception of a brand/company is critical to success. This case study analyzes the effectiveness of Adidas\u27s distinct “collaborative approach” to supply chain management, which is characterized by not only monitoring and auditing suppliers, but also training them to make Adidas’s standards their own and approaching suppliers with the intention of building long-term relationships where the suppliers can become self-sufficient. This study reviews the structure of Adidas\u27s supply chain, the nature of Adidas\u27s collaborative approach to supply chain management, the benefits that collaboration provides over the conventional compliance approach to supply chain management, and the potential shortcomings of Adidas\u27s approach. A conclusion is reached that the collaborative approach is the backbone of Adidas\u27s success as one of the largest apparel manufacturers in the world because of its holistic nature and consideration for unique cultural challenges

Cost Benefit Analysis of the Keystone XL Pipeline

The Keystone XL pipeline is one of the most controversial topics in North America over the last five years. The debate is based on the trade‐off between Canadian oil sands as a usable energy resource and the environmental effects associated with the extraction and refining of the oil. The green house gasses emitted from the extraction and refining of oil sands produces several environmental concerns that make the proposed pipeline controversial. On the other hand, Canadian oil companies see a significant benefit from the ability of Canadian oil reaching international markets. TransCanada, a 79.99 percent owner of the pipeline, conducted an evaluation of the pipeline; however, their valuations have been questioned due to their bias. This paper provides an objective analysis of the pipeline, from the perspective of Canada. Through conducting a Cost‐Benefit Analysis, it finds that the pipeline provides a net‐benefit of $118 billion dollars to Canada and its citizens