http://www.mdpi.com/journal/entropy/special_issues/quantum-information/ Submission All manuscripts should be submitted to entropy@mdpi.com with a copy to the Guest Editor. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website. Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed Open Access monthly journal published by MDPI. Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this Open Access journal is 1000 CHF per accepted paper. http://www.mdpi.com/1099-4300/12/11/2268/ Numerical simulation of quantum systems is crucial to further our understanding of natural phenomena. Many systems of key interest and importance, in areas such as superconducting materials and quantum chemistry, are thought to be described by models which we cannot solve with sufficient accuracy, neither analytically nor numerically with classical computers. Using a quantum computer to simulate such quantum systems has been viewed as a key application of quantum computation from the very beginning of the field in the 1980s. Moreover, useful results beyond the reach of classical computation are expected to be accessible with fewer than a hundred qubits, making quantum simulation potentially one of the earliest practical applications of quantum computers. In this paper we survey the theoretical and experimental development of quantum simulation using quantum computers, from the first ideas to the intense research efforts currently underway. http://www.mdpi.com/1099-4300/12/11/2268/ Mon, 15 Nov 2010 00:00:00 CET Entropy 2010-11-15 12 11 Review 2268 2307 1099-4300 Using Quantum Computers for Quantum Simulation 2010-11-15 doi: 10.3390/e12112268 Katherine L. Brown William J. Munro Vivien M. Kendon http://www.mdpi.com/1099-4300/12/7/1799/ Convex roof extensions are widely used to create entanglement measures in quantum information theory. The aim of the article is to present some tools which could be helpful for their treatment. Sections 2 and 3 introduce into the subject. It follows descriptions of the Wootters' method, of the "subtraction procedure", and examples on how to use symmetries. http://www.mdpi.com/1099-4300/12/7/1799/ Tue, 20 Jul 2010 00:00:00 CEST Entropy 2010-07-20 12 7 Article 1799 1832 1099-4300 Roofs and Convexity 2010-07-20 doi: 10.3390/e12071799 Armin Uhlmann http://www.mdpi.com/1099-4300/12/7/1721/ Charge sensing with quantum point-contacts (QPCs) is a technique widely used in semiconductor quantum-dot research. Understanding the physics of this measurement process, as well as finding ways of suppressing unwanted measurement back-action, are therefore both desirable. In this article, we present experimental studies targeting these two goals. Firstly, we measure the effect of a QPC on electron tunneling between two InAs quantum dots, and show that a model based on the QPC’s shot-noise can account for it. Secondly, we discuss the possibility of lowering the measurement current (and thus the back-action) used for charge sensing by correlating the signals of two independent measurement channels. The performance of this method is tested in a typical experimental setup. http://www.mdpi.com/1099-4300/12/7/1721/ Tue, 29 Jun 2010 00:00:00 CEST Entropy 2010-06-29 12 7 Article 1721 1732 1099-4300 Measurement Back-Action in Quantum Point-Contact Charge Sensing 2010-06-29 doi: 10.3390/e12071721 Küng Gustavsson Choi Shorubalko Pfäffli Hassler Blatter Reinwald Wegscheider Schön Ihn Ensslin http://www.mdpi.com/1099-4300/12/6/1612/ Using the graphical calculus and integration techniques introduced by the authors, we study the statistical properties of outputs of products of random quantum channels for entangled inputs. In particular, we revisit and generalize models of relevance for the recent counterexamples to the minimum output entropy additivity problems. Our main result is a classification of regimes for which the von Neumann entropy is lower on average than the elementary bounds that can be obtained with linear algebra techniques. http://www.mdpi.com/1099-4300/12/6/1612/ Wed, 23 Jun 2010 00:00:00 CEST Entropy 2010-06-23 12 6 Article 1612 1631 1099-4300 Eigenvalue and Entropy Statistics for Products of Conjugate Random Quantum Channels 2010-06-23 doi: 10.3390/e12061612 Collins Nechita