@inproceedings{KruegerMauerer, author = {Kr{\"u}ger, Tom and Mauerer, Wolfgang}, title = {Quantum Annealing-Based Software Components}, series = {Proceedings of the IEEE/ACM 42nd International Conference on Software Engineering Workshops (ICSE'20): Seoul Republic of Korea 27.06.2020 - 19.07.2020}, booktitle = {Proceedings of the IEEE/ACM 42nd International Conference on Software Engineering Workshops (ICSE'20): Seoul Republic of Korea 27.06.2020 - 19.07.2020}, publisher = {Association for Computing Machinery}, address = {New York, NY}, isbn = {9781450379632}, doi = {10.1145/3387940.3391472}, pages = {445 -- 450}, abstract = {Quantum computers have the potential of solving problems more efficiently than classical computers. While first commercial prototypes have become available, the performance of such machines in practical application is still subject to exploration. Quantum computers will not entirely replace classical machines, but serve as accelerators for specific problems. This necessitates integrating quantum computational primitives into existing applications. In this paper, we perform a case study on how to augment existing software with quantum computational primitives for the Boolean satisfiability problem (SAT) implemented using a quantum annealer (QA). We discuss relevant quality measures for quantum components, and show that mathematically equivalent, but structurally different ways of transforming SAT to a QA can lead to substantial differences regarding these qualities. We argue that engineers need to be aware that (and which) details, although they may be less relevant in traditional software engineering, require considerable attention in quantum computing.}, language = {en} } @inproceedings{GaborZielinskiFeldetal., author = {Gabor, Thomas and Zielinski, Sebastian and Feld, Sebastian and Roch, Christoph and Seidel, Christian and Neukart, Florian and Galter, Isabella and Mauerer, Wolfgang and Linnhoff-Popien, Claudia}, title = {Assessing Solution Quality of 3SAT on a Quantum Annealing Platform}, series = {Quantum Technology and Optimization Problems : First International Workshop, QTOP 2019, Munich, Germany, March 18, 2019, Proceedings}, volume = {11413}, booktitle = {Quantum Technology and Optimization Problems : First International Workshop, QTOP 2019, Munich, Germany, March 18, 2019, Proceedings}, editor = {Feld, Sebastian and Linnhoff-Popien, Claudia}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-14081-6}, doi = {10.1007/978-3-030-14082-3_3}, pages = {23 -- 35}, language = {en} } @article{MauererScherzinger, author = {Mauerer, Wolfgang and Scherzinger, Stefanie}, title = {Digitale Forschungswerkzeuge : Nachhaltigkeit f{\"u}r Software und Daten}, series = {Forschung \& Lehre (Forschung und Lehre)}, volume = {28}, journal = {Forschung \& Lehre (Forschung und Lehre)}, number = {10}, publisher = {Zentrum f{\"u}r Wissenschaftsmanagement e.V. (ZWM)
}, organization = {Deutscher Hochschullehrerverband}, pages = {816 -- 817}, abstract = {Die wissenschaftliche Reproduktionskrise hat den Blick auf digitale Forschungswerkzeuge intensiviert. Auch wenn der Mehraufwand f{\"u}r Reproduzierbarkeit und Zug{\"a}nglichkeit zunehmend anerkannt wird, existieren noch Defizite in der Umsetzung, wenn es darum geht, die Datenbasis und Forschungswerkzeuge verf{\"u}gbar zu machen}, language = {de} } @article{BayerstadlerBecquinBinderetal., author = {Bayerstadler, Andreas and Becquin, Guillaume and Binder, Julia and Botter, Thierry and Ehm, Hans and Ehmer, Thomas and Erdmann, Marvin and Gaus, Norbert and Harbach, Philipp and Hess, Maximilian and Klepsch, Johannes and Leib, Martin and Luber, Sebastian and Luckow, Andre and Mansky, Maximilian and Mauerer, Wolfgang and Neukart, Florian and Niedermeier, Christoph and Palackal, Lilly and Pfeiffer, Ruben and Polenz, Carsten and Sepulveda, Johanna and Sievers, Tammo and Standen, Brian and Streif, Michael and Strohm, Thomas and Utschig-Utschig, Clemens and Volz, Daniel and Weiss, Horst and Winter, Fabian}, title = {Industry quantum computing applications}, series = {EPJ Quantum Technology}, volume = {8}, journal = {EPJ Quantum Technology}, publisher = {Springer}, organization = {Springer}, doi = {10.1140/epjqt/s40507-021-00114-x}, pages = {1 -- 17}, abstract = {Quantum computing promises to overcome computational limitations with better and faster solutions for optimization, simulation, and machine learning problems. Europe and Germany are in the process of successfully establishing research and funding programs with the objective to dvance the technology's ecosystem and industrialization, thereby ensuring digital sovereignty, security, and competitiveness. Such an ecosystem comprises hardware/software solution providers, system integrators, and users from research institutions, start-ups, and industry. The vision of the Quantum Technology and Application Consortium (QUTAC) is to establish and advance the quantum computing ecosystem, supporting the ambitious goals of the German government and various research programs. QUTAC is comprised of ten members representing different industries, in particular automotive manufacturing, chemical and pharmaceutical production, insurance, and technology. In this paper, we survey the current state of quantum computing in these sectors as well as the aerospace industry and identify the contributions of QUTAC to the ecosystem. We propose an application-centric approach for the industrialization of the technology based on proven business impact. This paper identifies 24 different use cases. By formalizing high-value use cases into well-described reference problems and benchmarks, we will guide technological progress and eventually commercialization. Our results will be beneficial to all ecosystem participants, including suppliers, system integrators, software developers, users, policymakers, funding program managers, and investors.}, language = {en} } @article{GabrielWittmannSychetal., author = {Gabriel, Christian and Wittmann, Christoffer and Sych, Denis and Dong, Ruifang and Mauerer, Wolfgang and Andersen, Ulrik L. and Marquardt, Christoph and Leuchs, Gerd}, title = {A generator for unique quantum random numbers based on vacuum states}, series = {Nature Photonics}, volume = {4}, journal = {Nature Photonics}, number = {10}, publisher = {Springer}, organization = {Springer}, doi = {10.1038/nphoton.2010.197}, pages = {711 -- 715}, abstract = {Random numbers are a valuable component in diverse applications that range from simulations over gambling to cryptography. The quest for true randomness in these applications has engendered a large variety of different proposals for producing random numbers based on the foundational unpredictability of quantum mechanics4,5,6,7,8,9,10,11. However, most approaches do not consider that a potential adversary could have knowledge about the generated numbers, so the numbers are not verifiably random and unique12,13,14,15. Here we present a simple experimental setup based on homodyne measurements that uses the purity of a continuous-variable quantum vacuum state to generate unique random numbers. We use the intrinsic randomness in measuring the quadratures of a mode in the lowest energy vacuum state, which cannot be correlated to any other state. The simplicity of our source, combined with its verifiably unique randomness, are important attributes for achieving high-reliability, high-speed and low-cost quantum random number generators.}, language = {en} } @article{ColdenstrodtRongeLundeenPregnelletal., author = {Coldenstrodt-Ronge, Hendrik B. and Lundeen, Jeff S. and Pregnell, Kenny L. and Feito, Alvaro and Smith, Brian J. and Mauerer, Wolfgang and Silberhorn, Christine and Eisert, Jens and Plenio, Martin B. and Walmsley, Ian A.}, title = {A proposed testbed for detector tomography}, series = {Journal of Modern Optics}, volume = {56}, journal = {Journal of Modern Optics}, number = {2-3}, publisher = {Taylor\&Francis}, doi = {10.1080/09500340802304929}, pages = {432 -- 441}, abstract = {Measurement is the only part of a general quantum system that has yet to be characterised experimentally in a complete manner. Detector tomography provides a procedure for doing just this; an arbitrary measurement device can be fully characterised, and thus calibrated, in a systematic way without access to its components or its design. The result is a reconstructed POVM containing the measurement operators associated with each measurement outcome. We consider two detectors, a single-photon detector and a photon-number counter, and propose an easily realised experimental apparatus to perform detector tomography on them. We also present a method of visualising the resulting measurement operators.}, language = {en} } @article{MauererAvenhausHelwigetal., author = {Mauerer, Wolfgang and Avenhaus, Malte and Helwig, Wolfram and Silberhorn, Christine}, title = {How colors influence numbers: Photon statistics of parametric down-conversion}, series = {Physical Review A (Phys. Rev. A)}, volume = {80}, journal = {Physical Review A (Phys. Rev. A)}, number = {5}, publisher = {American Physical Society}, doi = {10.1103/physreva.80.053815}, abstract = {Parametric down-conversion (PDC) is a technique of ubiquitous experimental significance in the production of nonclassical, photon-number-correlated twin beams. Standard theory of PDC as a two-mode squeezing process predicts and homodyne measurements observe a thermal photon number distribution per beam. Recent experiments have obtained conflicting distributions. In this article, we explain the observation by an a priori theoretical model solely based on directly accessible physical quantities. We compare our predictions with experimental data and find excellent agreement.}, language = {en} } @article{MauererSawallischHillieretal., author = {Mauerer, Wolfgang and Sawallisch, J. and Hillier, G. and Oberth{\"u}r, S. and H{\"o}nick, S.}, title = {Real-Time Android: Achieving determinism and ease of use}, series = {Embedded Wold Conference; Nuremberg, Germany, February 25, 2014 - February 27, 2014}, journal = {Embedded Wold Conference; Nuremberg, Germany, February 25, 2014 - February 27, 2014}, pages = {1 -- 7}, language = {en} } @article{RohdeMauererSilberhorn, author = {Rohde, Peter P. and Mauerer, Wolfgang and Silberhorn, Christine}, title = {Spectral structure and decompositions of optical states, and their applications}, series = {New Journal of Physics}, volume = {9}, journal = {New Journal of Physics}, number = {4}, publisher = {IOP Publishing}, doi = {10.1088/1367-2630/9/4/091}, pages = {91}, abstract = {We discuss the spectral structure and decomposition of multi-photon states. Ordinarily 'multi-photon states' and 'Fock states' are regarded as synonymous. However, when the spectral degrees of freedom are included this is not the case, and the class of 'multi-photon' states is much broader than the class of 'Fock' states. We discuss the criteria for a state to be considered a Fock state. We then address the decomposition of general multi-photon states into bases of orthogonal eigenmodes, building on existing multi-mode theory, and introduce an occupation number representation that provides an elegant description of such states. This representation allows us to work in bases imposed by experimental constraints, simplifying calculations in many situations. Finally we apply this technique to several example situations, which are highly relevant for state of the art experiments. These include Hong-Ou-Mandel interference, spectral filtering, finite bandwidth photo-detection, homodyne detection and the conditional preparation of Schr{\"o}dinger kitten and Fock states. Our techniques allow for very simple descriptions of each of these examples.}, language = {en} } @article{HelwigMauererSilberhorn, author = {Helwig, Wolfram and Mauerer, Wolfgang and Silberhorn, Christine}, title = {Multimode states in decoy-based quantum-key-distribution protocols}, series = {Physical Review A}, volume = {80}, journal = {Physical Review A}, number = {5}, publisher = {American Physical Society}, doi = {10.1103/physreva.80.052326}, abstract = {Every security analysis of quantum-key distribution (QKD) relies on a faithful modeling of the employed quantum states. Many photon sources, such as for instance a parametric down-conversion (PDC) source, require a multimode description but are usually only considered in a single-mode representation. In general, the important claim in decoy-based QKD protocols for indistinguishability between signal and decoy states does not hold for all sources. We derive bounds on the single-photon transmission probability and error rate for multimode states and apply these bounds to the output state of a PDC source. We observe two opposing effects on the secure key rate. First, the multimode structure of the state gives rise to a new attack that decreases the key rate. Second, more contributing modes change the photon number distribution from a thermal toward a Poissonian distribution, which increases the key rate.}, language = {en} } @article{MauererHelwigSilberhorn, author = {Mauerer, Wolfgang and Helwig, Wolfram and Silberhorn, Christine}, title = {Recent developments in quantum key distribution: Theory and practice}, series = {Annalen der Physik}, volume = {17}, journal = {Annalen der Physik}, number = {2-3}, publisher = {Wiley}, doi = {10.1002/andp.200710284}, pages = {158 -- 175}, abstract = {Quantum key distribution is among the foremost applications of quantum mechanics, both in terms of fundamental physics and as a technology on the brink of commercial deployment. Starting from principal schemes and initial proofs of unconditional security for perfect systems, much effort has gone into providing secure schemes which can cope with numerous experimental imperfections unavoidable in real world implementations. In this paper, we provide a comparison of various schemes and protocols. We analyse their efficiency and performance when implemented with imperfect physical components. We consider how experimental faults are accounted for using effective parameters. We compare various recent protocols and provide guidelines as to which components propose best advances when being improved.}, language = {en} } @article{AvenhausColdenstrodtRongeLaihoetal., author = {Avenhaus, Malte and Coldenstrodt-Ronge, Hendrik B. and Laiho, K. and Mauerer, Wolfgang and Walmsley, I. A. and Silberhorn, Christine}, title = {Photon Number Statistics of Multimode Parametric Down-Conversion}, series = {Physical Review Letters}, volume = {101}, journal = {Physical Review Letters}, number = {5}, publisher = {American Physical Society}, doi = {10.1103/physrevlett.101.053601}, abstract = {We experimentally analyze the complete photon number statistics of parametric down-conversion and ascertain the influence of multimode effects. Our results clearly reveal a difference between single-mode theoretical description and the measured distributions. Further investigations assure the applicability of loss-tolerant photon number reconstruction and prove strict photon number correlation between signal and idler modes.}, language = {en} } @article{MauererSilberhorn, author = {Mauerer, Wolfgang and Silberhorn, Christine}, title = {Quantum key distribution with passive decoy state selection}, series = {Physical Review A}, volume = {75}, journal = {Physical Review A}, number = {5}, publisher = {American Physical Society}, doi = {10.1103/physreva.75.050305}, abstract = {We propose a quantum key distribution scheme which closely matches the performance of a perfect single photon source. It nearly attains the physical upper bound in terms of key generation rate and maximally achievable distance. Our scheme relies on a practical setup based on a parametric downconversion source and present day, nonideal photon-number detection. Arbitrary experimental imperfections which lead to bit errors are included. We select decoy states by classical postprocessing. This allows one to improve the effective signal statistics and achievable distance.}, language = {en} } @book{Mauerer, author = {Mauerer, Wolfgang}, title = {Professional Linux kernel architecture}, series = {Wrox professional guides}, journal = {Wrox professional guides}, publisher = {Wiley}, address = {Indianapolis}, isbn = {9780470343432}, abstract = {Find an introduction to the architecture, concepts and algorithms of the Linux kernel in Professional Linux Kernel Architecture, a guide to the kernel sources and large number of connections among subsystems. Find an introduction to the relevant structures and functions exported by the kernel to userland, understand the theoretical and conceptual aspects of the Linux kernel and Unix derivatives, and gain a deeper understanding of the kernel. Learn how to reduce the vast amount of information contained in the kernel sources and obtain the skills necessary to understand the kernel sources.}, language = {en} } @article{Mauerer, author = {Mauerer, Wolfgang}, title = {Datenvisualisierung mit Ggplot2}, series = {Linux-Magazin}, journal = {Linux-Magazin}, number = {3}, publisher = {Linux New Media AG}, abstract = {Wer seine Daten mit ansehnlichen und informativen Graphen veranschaulichen m{\"o}chte, braucht meist viel Geduld. Die R-Erweiterung Ggplot2 bringt System in die Grafik, dr{\"u}ckt sich in knappem Quellcode aus und bl{\"a}st frischen Wind in den Alltag der Datenvisualisierung.}, language = {en} } @book{Mauerer, author = {Mauerer, Wolfgang}, title = {Linux-Kernelarchitektur : Konzepte Strukturen und Algorithmen von Kernel 2.6}, publisher = {Hanser}, address = {M{\"u}nchen}, isbn = {9783446225664}, language = {de} } @book{Mauerer, author = {Mauerer, Wolfgang}, title = {Textverarbeitung mit LATEX 2e [2 epsilon] unter UNIX}, publisher = {Hanser}, address = {M{\"u}nchen}, isbn = {9783446189096}, language = {de} } @article{Mauerer, author = {Mauerer, Wolfgang}, title = {Gimp-Perl: Gimp scripting for the rest of us}, series = {Linux Gazette}, journal = {Linux Gazette}, number = {51}, issn = {1934-371X}, language = {en} } @inproceedings{MurrMauerer, author = {Murr, Florian and Mauerer, Wolfgang}, title = {McFSM: Globally Taming Complex Systems}, series = {2017 IEEE/ACM 3rd International Workshop on Software Engineering for Smart Cyber-Physical Systems (SEsCPS), 21-21 May 2017, Buenos Aires, Argentina}, booktitle = {2017 IEEE/ACM 3rd International Workshop on Software Engineering for Smart Cyber-Physical Systems (SEsCPS), 21-21 May 2017, Buenos Aires, Argentina}, publisher = {IEEE}, doi = {10.1109/SEsCPS.2017.7}, pages = {26 -- 29}, abstract = {Industrial computing devices, in particular cyber-physical, real-time and safety-critical systems, focus on reacting to external events and the need to cooperate with other devices to create a functional system. They are often implemented with languages that focus on a simple, local description of how a component reacts to external input data and stimuli. Despite the trend in modern software architectures to structure systems into largely independent components, the remaining interdependencies still create rich behavioural dynamics even for small systems. Standard and industrial programming approaches do usually not model or extensively describe the global properties of an entire system. Although a large number of approaches to solve this dilemma have been suggested, it remains a hard and error-prone task to implement systems with complex interdependencies correctly. We introduce multiple coupled finite state machines (McFSMs), a novel mechanism that allows us to model and manage such interdependencies. It is based on a consistent, well-structured and simple global description. A sound theoretical foundation is provided, and associated tools allow us to generate efficient low-level code in various programming languages using model-driven techniques. We also present a domain specific language to express McFSMs and their connections to other systems, to model their dynamic behaviour, and to investigate their efficiency and correctness at compile-time.}, language = {en} } @inproceedings{RamsauerKiszkaMauerer, author = {Ramsauer, Ralf and Kiszka, Jan and Mauerer, Wolfgang}, title = {A Novel Software Architecture for Mixed Criticality Systems}, series = {Digital Transformation in Semiconductor Manufacturing: Proceedings of the 1st and 2nd European Advances in Digital Transformation Conference, EADTC 2018, Zittau, Germany and EADTC 2019, Milan, Italy}, booktitle = {Digital Transformation in Semiconductor Manufacturing: Proceedings of the 1st and 2nd European Advances in Digital Transformation Conference, EADTC 2018, Zittau, Germany and EADTC 2019, Milan, Italy}, editor = {Keil, Sophia and Lasch, Rainer and Lindner, Fabian and Lohmer, Jacob}, publisher = {Springer International Publishing}, address = {Cham}, doi = {10.1007/978-3-030-48602-0_11}, pages = {121 -- 128}, abstract = {The advent of multi-core CPUs in nearly all embedded markets has prompted an architectural trend towards combining safety critical and uncritical software on single hardware units. We present a novel architecture for mixed criticality systems based on Linux that allows us to consolidate critical and uncritical parts onto a single hardware unit. CPU virtualisation extensions enable strict and static partitioning of hardware by direct assignment of resources, which allows us to boot additional operating systems or bare metal applications running aside Linux. The hypervisor Jailhouse is at the core of the architecture and ensures that the resulting domains may serve workloads of different criticality and can not interfere in an unintended way. This retains Linux's feature-richness in uncritical parts, while frugal safety and real-time critical applications execute in isolated domains. Architectural simplicity is a central aspect of our approach and a precondition for reliable implementability and successful certification. While standard virtualisation extensions provided by current hardware seem to suffice for a straight forward implementation of our approach, there are a number of further limitations that need to be worked around. This paper discusses the arising issues, and evaluates the suitability of our approach for real-world safety and real-time critical scenarios.}, language = {en} } @inproceedings{RamsauerKiszkaLohmannetal., author = {Ramsauer, Ralf and Kiszka, Jan and Lohmann, Daniel and Mauerer, Wolfgang}, title = {Look Mum, no VM Exits! (Almost)}, series = {Proceedings of the 13th Annual Workshop on Operating Systems Platforms for Embedded Real-Time Applications (OSPERT '17)}, booktitle = {Proceedings of the 13th Annual Workshop on Operating Systems Platforms for Embedded Real-Time Applications (OSPERT '17)}, doi = {10.48550/arXiv.1705.06932}, abstract = {Multi-core CPUs are a standard component in many modern embedded systems. Their virtualisation extensions enable the isolation of services, and gain popularity to implement mixed-criticality or otherwise split systems. We present Jailhouse, a Linux-based, OS-agnostic partitioning hypervisor that uses novel architectural approaches to combine Linux, a powerful general-purpose system, with strictly isolated special-purpose components. Our design goals favour simplicity over features, establish a minimal code base, and minimise hypervisor activity. Direct assignment of hardware to guests, together with a deferred initialisation scheme, offloads any complex hardware handling and bootstrapping issues from the hypervisor to the general purpose OS. The hypervisor establishes isolated domains that directly access physical resources without the need for emulation or paravirtualisation. This retains, with negligible system overhead, Linux's feature-richness in uncritical parts, while frugal safety and real-time critical workloads execute in isolated, safe domains.}, language = {en} } @inproceedings{PichaBradaRamsaueretal., author = {Picha, Petr and Brada, Premek and Ramsauer, Ralf and Mauerer, Wolfgang}, title = {Towards Architect's Activity Detection through a Common Model for Project Pattern Analysis}, series = {First International Workshop on the Social and Organization Dimensions of Software, 5-7 April 2017, Gothenburg, Sweden}, booktitle = {First International Workshop on the Social and Organization Dimensions of Software, 5-7 April 2017, Gothenburg, Sweden}, publisher = {IEEE}, doi = {10.1109/ICSAW.2017.46}, pages = {175 -- 178}, abstract = {Software development projects leave a large amount of data in repositories of Application Lifecycle Management (ALM) tools. These data contain detailed histories of their respective projects, their results and decisions made along the way. Analysis of such data helps uncover various interesting facts about projects, e.g. their socio-technical structures and the actual (vs. purported) roles of team members. Based on experiences with tools supporting our research we are convinced that it is feasible to consolidate data from different ALM tools, tapping into the situation common in real-life projects. In this paper we report on our work towards a shared common data model and tool integration aimed at improved project analysis. We discuss how this can help in the identification of architects in the project organizational structures, their activity patterns and collaboration with other team roles.}, language = {en} } @inproceedings{RamsauerLohmannMauerer, author = {Ramsauer, Ralf and Lohmann, Daniel and Mauerer, Wolfgang}, title = {Observing Custom Software Modifications: A Quantitative Approach of Tracking the Evolution of Patch Stacks}, series = {Proceedings of the 12th International Symposium on Open Collaboration (OpenSym '16)}, booktitle = {Proceedings of the 12th International Symposium on Open Collaboration (OpenSym '16)}, editor = {Wassermann, Tony}, publisher = {ACM}, address = {New York}, doi = {10.1145/2957792.2957810}, pages = {1 -- 4}, abstract = {Modifications to open-source software (OSS) are often provided in the form of "patch stacks" -- sets of changes (patches) that modify a given body of source code. Maintaining patch stacks over extended periods of time is problematic when the underlying base project changes frequently. This necessitates a continuous and engineering-intensive adaptation of the stack. Nonetheless, long-term maintenance is an important problem for changes that are not integrated into projects, for instance when they are controversial or only of value to a limited group of users. We present and implement a methodology to systematically examine the temporal evolution of patch stacks, track non-functional properties like integrability and maintainability, and estimate the eventual economic and engineering effort required to successfully develop and maintain patch stacks. Our results provide a basis for quantitative research on patch stacks, including statistical analyses and other methods that lead to actionable advice on the construction and long-term maintenance of custom extensions to OSS.}, language = {en} } @inproceedings{HofmannRiehleKolassaetal., author = {Hofmann, Gottfried and Riehle, Dirk and Kolassa, Carsten and Mauerer, Wolfgang}, title = {A Dual Model of Open Source License Growth}, series = {Open Source Software: Quality Verification : 9th IFIP WG 2.13 International Conference, OSS 2013, Koper-Capodistria, Slovenia, June 25-28, 2013, Proceedings}, volume = {404}, booktitle = {Open Source Software: Quality Verification : 9th IFIP WG 2.13 International Conference, OSS 2013, Koper-Capodistria, Slovenia, June 25-28, 2013, Proceedings}, publisher = {Springer}, address = {Berlin}, doi = {10.1007/978-3-642-38928-3_18}, pages = {245 -- 256}, abstract = {Every open source project needs to decide on an open source license. This decision is of high economic relevance: Just which license is the best one to help the project grow and attract a community? The most common question is: Should the project choose a restrictive (reciprocal) license or a more permissive one? As an important step towards answering this question, this paper analyses actual license choice and correlated project growth from ten years of open source projects. It provides closed analytical models and finds that around 2001 a reversal in license choice occurred from restrictive towards permissive licenses.}, language = {en} } @misc{MauererWagner, author = {Mauerer, Wolfgang and Wagner, Daniel}, title = {Cyclic Tests Unleashed: Large-Scale RT Analysis with Jitterdebugger}, series = {Open Source Summit, North America, 17.07.2019}, journal = {Open Source Summit, North America, 17.07.2019}, language = {en} } @inproceedings{Mauerer, author = {Mauerer, Wolfgang}, title = {Are any big brothers watching you, and if yes, what can they tell about Debian}, series = {DebConf18 Hsinchu, Taiwan}, booktitle = {DebConf18 Hsinchu, Taiwan}, abstract = {Debian, as a collection of software packages and components, is known to be one of the largest software projects in the history of mankind. Combined with a traceable history over many years, the artefacts created by Debian developers and users make it one of science's favourite targets to quantitatively or qualitatively understand how real-world software development works (or does not), how people collaborate, and many other other related questions. Unfortunately, while scientists make ample use of the resources and artefacts created by FLOSS and friends, the exchange of insights and ideas does not seem to extend in both directions: Developers, users and integrators are often unaware of results obtained in science. This talk will introduce the Debian community to a selection the most important results obtained by scientific (software engineering) research, with a special focus on large-scale socio-technical analysis of projects like Debian, and the possible implications and improvements these may bring to Debian development itself.}, language = {en} } @misc{MauererRamsauer, author = {Mauerer, Wolfgang and Ramsauer, Ralf}, title = {Torturing Git for Fun and Profit}, series = {Microsoft Developer Meetup Regensburg 02.04.2019}, journal = {Microsoft Developer Meetup Regensburg 02.04.2019}, abstract = {In diesem Talk blicken Prof. Dr. Wolfgang Mauerer und Ralf Ramsauer unter die Haube des verteilten Versionskontrollsystems Git. Neben einer genauen Beschreibung der Strukturen und Plumbing APIs, mit denen Git intern Commits erzeugt und verkn{\"u}pft, gehen die Vortragenden auch auf n{\"u}tzliche Features und Standards ein, welche die Kollaborition in großen Open-Source Projekten erleichtern.}, language = {en} } @article{FeldRochGaboretal., author = {Feld, Sebastian and Roch, Christoph and Gabor, Thomas and Seidel, Christian and Neukart, Florian and Galter, Isabella and Mauerer, Wolfgang and Linnhoff-Popien, Claudia}, title = {A Hybrid Solution Method for the Capacitated Vehicle Routing Problem Using a Quantum Annealer}, series = {Frontiers in ICT}, volume = {6}, journal = {Frontiers in ICT}, publisher = {Frontiers}, doi = {10.3389/fict.2019.00013}, pages = {1 -- 13}, abstract = {he Capacitated Vehicle Routing Problem (CVRP) is an NP-optimization problem (NPO) that has been of great interest for decades for both, science and industry. The CVRP is a variant of the vehicle routing problem characterized by capacity constrained vehicles. The aim is to plan tours for vehicles to supply a given number of customers as efficiently as possible. The problem is the combinatorial explosion of possible solutions, which increases superexponentially with the number of customers. Classical solutions provide good approximations to the globally optimal solution. D-Wave's quantum annealer is a machine designed to solve optimization problems. This machine uses quantum effects to speed up computation time compared to classic computers. The problem on solving the CVRP on the quantum annealer is the particular formulation of the optimization problem. For this, it has to be mapped onto a quadratic unconstrained binary optimization (QUBO) problem. Complex optimization problems such as the CVRP can be translated to smaller subproblems and thus enable a sequential solution of the partitioned problem. This work presents a quantum-classic hybrid solution method for the CVRP. It clarifies whether the implementation of such a method pays off in comparison to existing classical solution methods regarding computation time and solution quality. Several approaches to solving the CVRP are elaborated, the arising problems are discussed, and the results are evaluated in terms of solution quality and computation time.}, language = {en} } @inproceedings{RamsauerBulwahnLohmannetal., author = {Ramsauer, Ralf and Bulwahn, Lukas and Lohmann, Daniel and Mauerer, Wolfgang}, title = {The Sound of Silence : Mining Security Vulnerabilities from Secret Integration Channels in Open-Source Projects}, series = {Proceedings of the 2020 ACM SIGSAC Conference on Cloud Computing Security Workshop: 09.11.2020, virtual event}, booktitle = {Proceedings of the 2020 ACM SIGSAC Conference on Cloud Computing Security Workshop: 09.11.2020, virtual event}, editor = {Zhang, Yinqian and Sion, Radu}, publisher = {ACM}, address = {New York, NY, USA}, isbn = {9781450380843}, doi = {10.1145/3411495.3421360}, pages = {147 -- 157}, abstract = {Public development processes are a key characteristic of open source projects. However, fixes for vulnerabilities are usually discussed privately among a small group of trusted maintainers, and integrated without prior public involvement. This is supposed to prevent early disclosure, and cope with embargo and non-disclosure agreement (NDA) rules. While regular development activities leave publicly available traces, fixes for vulnerabilities that bypass the standard process do not. We present a data-mining based approach to detect code fragments that arise from such infringements of the standard process. By systematically mapping public development artefacts to source code repositories, we can exclude regular process activities, and infer irregularities that stem from non-public integration channels. For the Linux kernel, the most crucial component of many systems, we apply our method to a period of seven months before the release of Linux 5.4. We find 29 commits that address 12 vulnerabilities. For these vulnerabilities, our approach provides a temporal advantage of 2 to 179 days to design exploits before public disclosure takes place, and fixes are rolled out. Established responsible disclosure approaches in open development processes are supposed to limit premature visibility of security vulnerabilities. However, our approach shows that, instead, they open additional possibilities to uncover such changes that thwart the very premise. We conclude by discussing implications and partial countermeasures.}, language = {en} } @inproceedings{MauererSilberhorn, author = {Mauerer, Wolfgang and Silberhorn, Christine}, title = {Numerical Analysis of Parametric Downconversion}, series = {AIP Conference Proceedings}, volume = {1110}, booktitle = {AIP Conference Proceedings}, number = {1}, publisher = {AIP Publishing}, doi = {10.1063/1.3131312}, abstract = {Parametric downconversion (PDC) is a popular technique to produce twin beams of photons that are entangled in multiple degrees of freedom. The generated states form the basis for numerous applications that require entanglement. An exact quantification of this resource is therefore essential, for instance for quantum cryptography that relies on a complete knowledge of the correlation contained in the state. While the determination of an entanglement monotone for the PDC process is only possible analytically in special cases, an exact calculation must usually be performed numerically. Recent work by Mikhailova et al. [2] analyses a certain class of PDC states for which the concurrence entanglement measure can be obtained by an analytical approximation. In this contribution, we analyse the validity of the approximation by comparison with exact numerical methods.}, language = {en} } @misc{Mauerer, author = {Mauerer, Wolfgang}, title = {OSS Community, Health and Ecosystem Research: Theory and, or Theory versus Practice?}, series = {2nd International Workshop on Software Health (SoHEAL@ICSE, Montr{\´e}al), 2019}, journal = {2nd International Workshop on Software Health (SoHEAL@ICSE, Montr{\´e}al), 2019}, language = {en} } @inproceedings{RamsauerLohmannMauerer, author = {Ramsauer, Ralf and Lohmann, Daniel and Mauerer, Wolfgang}, title = {System Software for Manufacturing Systems}, series = {Proc. First European Advances in Digital Transformation Conference, (2018)}, booktitle = {Proc. First European Advances in Digital Transformation Conference, (2018)}, language = {en} } @inproceedings{Mauerer, author = {Mauerer, Wolfgang}, title = {A Virtual Computing Platform for the Internet of Things}, series = {Embedded Linux Conference (San Diego), 2016}, booktitle = {Embedded Linux Conference (San Diego), 2016}, language = {de} } @inproceedings{WinterspergerSafiMauerer, author = {Wintersperger, Karen and Safi, Hila and Mauerer, Wolfgang}, title = {QPU-System Co-Design for Quantum HPC Accelerators?}, series = {Architecture of Computing Systems: 35th International Conference, ARCS 2022, Heilbronn, Germany, September 13-15, 2022, Proceedings}, booktitle = {Architecture of Computing Systems: 35th International Conference, ARCS 2022, Heilbronn, Germany, September 13-15, 2022, Proceedings}, publisher = {Springer}, isbn = {978-3-031-21866-8}, doi = {10.1007/978-3-031-21867-5_7}, pages = {100 -- 114}, abstract = {The use of quantum processing units (QPUs) promises speed-ups for solving computational problems, but the quantum devices currently available possess only a very limited number of qubits and suffer from considerable imperfections. One possibility to progress towards practical utility is to use a co-design approach: Problem formulation and algorithm, but also the physical QPU properties are tailored to the specific application. Since QPUs will likely be used as accelerators for classical computers, details of systemic integration into existing architectures are another lever to influence and improve the practical utility of QPUs. In this work, we investigate the influence of different parameters on the runtime of quantum programs on tailored hybrid CPU-QPU-systems. We study the influence of communication times between CPU and QPU, how adapting QPU designs influences quantum and overall execution performance, and how these factors interact. Using a simple model that allows for estimating which design choices should be subjected to optimisation for a given task, we provide an intuition to the HPC community on potentials and limitations of co-design approaches. We also discuss physical limitations for implementing the proposed changes on real quantum hardware devices.}, language = {en} } @unpublished{MurrMauerer, author = {Murr, Florian and Mauerer, Wolfgang}, title = {McFSM: Near Turing-Complete Finite-State Based Programming}, pages = {11}, abstract = {Finite state machines (FSMs) are an appealing mechanism for simple practical computations: They lend themselves to very effcient and deterministic implementation, are easy to understand, and allow for formally proving many properties of interest. Unfortunately, their computational power is deemed insuffcient for many tasks, and their usefulness has been further hampered by the state space explosion problem and other issues when na{\"i}vely trying to scale them to sizes large enough for many real-life applications. This paper expounds on theory and implementation of multiple coupled fnite state machines (McFSMs), a novel mechanism that combines benefits of FSMs with near Turing-complete, practical computing power, and that was designed from the ground up to support static analysis and reasoning. We develop an elaborate category-theoretical foundation based on non-deterministic Mealy machines, which gives a suitable algebraic description for novel ways of blending di\#erent computing models. Our experience is based on a domain specific language and an integrated development environment that can compile McFSM models to multiple target languages, applying it to use-cases based on industrial scenarios. We discuss properties and advantages of McFSMs, explain how the mechanism can interact with real-world systems and existing code without sacrificing provability, determinism or performance. We discuss how McFSMs can be used to replace and improve on commonly employed programming patterns, and show how their effcient handling of large state spaces enables them to be used as core building blocks for distributed, safety critical, and real-time systems of industrial complexity, which contributes to the longdesired goal of providing executable specifications.}, language = {en} } @inproceedings{MauererKlessingerScherzinger, author = {Mauerer, Wolfgang and Klessinger, Stefan and Scherzinger, Stefanie}, title = {Beyond the badge: reproducibility engineering as a lifetime skill}, series = {Proceedings 4th International Workshop on Software Engineering Education for the Next Generation SEENG 2022, 17 May 2022, Pittsburgh, PA, USA}, booktitle = {Proceedings 4th International Workshop on Software Engineering Education for the Next Generation SEENG 2022, 17 May 2022, Pittsburgh, PA, USA}, publisher = {ACM}, address = {New York, NY, USA}, isbn = {9781450393362}, doi = {10.1145/3528231.3528359}, pages = {1 -- 4}, abstract = {Ascertaining reproducibility of scientific experiments is receiving increased attention across disciplines. We argue that the necessary skills are important beyond pure scientific utility, and that they should be taught as part of software engineering (SWE) education. They serve a dual purpose: Apart from acquiring the coveted badges assigned to reproducible research, reproducibility engineering is a lifetime skill for a professional industrial career in computer science. SWE curricula seem an ideal fit for conveying such capabilities, yet they require some extensions, especially given that even at flagship conferences like ICSE, only slightly more than one-third of the technical papers (at the 2021 edition) receive recognition for artefact reusability. Knowledge and capabilities in setting up engineering environments that allow for reproducing artefacts and results over decades (a standard requirement in many traditional engineering disciplines), writing semi-literate commit messages that document crucial steps of a decision-making process and that are tightly coupled with code, or sustainably taming dynamic, quickly changing software dependencies, to name a few: They all contribute to solving the scientific reproducibility crisis, and enable software engineers to build sustainable, long-term maintainable, software-intensive, industrial systems. We propose to teach these skills at the undergraduate level, on par with traditional SWE topics.}, language = {en} } @inproceedings{WinkerGroppeUotilaetal., author = {Winker, Tobias and Groppe, Sven and Uotila, Valter Johan Edvard and Yan, Zhengtong and Lu, Jiaheng and Maja, Franz and Mauerer, Wolfgang}, title = {Quantum Machine Learning: Foundation, New Techniques, and Opportunities for Database Research}, series = {SIGMOD '23, proceedings of the 2023 International Conference on Management of Data: June 18-23, 2023, Seattle, WA, USA}, booktitle = {SIGMOD '23, proceedings of the 2023 International Conference on Management of Data: June 18-23, 2023, Seattle, WA, USA}, publisher = {ACM}, address = {New York}, doi = {10.1145/3555041.3589404}, pages = {8}, abstract = {In the last few years, the field of quantum computing has experienced remarkable progress. The prototypes of quantum computers already exist and have been made available to users through cloud services (e.g., IBM Q experience, Google quantum AI, or Xanadu quantum cloud). While fault-tolerant and large-scale quantum computers are not available yet (and may not be for a long time, if ever), the potential of this new technology is undeniable. Quantum algorithms havethe proven ability to either outperform classical approaches for several tasks, or are impossible to be efficiently simulated by classical means under reasonable complexity-theoretic assumptions. Even imperfect current-day technology is speculated to exhibit computational advantages over classical systems. Recent research is using quantum computers to solve machine learning tasks. Meanwhile, the database community already successfully applied various machine learning algorithms for data management tasks, so combining the fields seems to be a promising endeavour. However, quantum machine learning is a new research field for most database researchers. In this tutorial, we provide a fundamental introduction to quantum computing and quantum machine learning and show the potential benefits and applications for database research. In addition, we demonstrate how to apply quantum machine learning to the optimization of join order problem for databases.}, language = {en} } @unpublished{ThelenSafiMauerer, author = {Thelen, Simon and Safi, Hila and Mauerer, Wolfgang}, title = {Approximating under the Influence of Quantum Noise and Compute Power}, series = {Proceedings of WIHPQC@IEEE QCE}, journal = {Proceedings of WIHPQC@IEEE QCE}, abstract = {The quantum approximate optimisation algorithm (QAOA) is at the core of many scenarios that aim to combine the power of quantum computers and classical high-performance computing appliances for combinatorial optimisation. Several obstacles challenge concrete benefits now and in the foreseeable future: Imperfections quickly degrade algorithmic performance below practical utility; overheads arising from alternating between classical and quantum primitives can counter any advantage; and the choice of parameters or algorithmic variant can substantially influence runtime and result quality. Selecting the optimal combination is a non-trivial issue, as it not only depends on user requirements, but also on details of the hardware and software stack. Appropriate automation can lift the burden of choosing optimal combinations for end-users: They should not be required to understand technicalities like differences between QAOA variants, required number of QAOA layers, or necessary measurement samples. Yet, they should receive best-possible satisfaction of their non-functional requirements, be it performance or other. We determine factors that affect solution quality and temporal behaviour of four QAOA variants using comprehensive density-matrix-based simulations targeting three widely studied optimisation problems. Our simulations consider ideal quantum computation, and a continuum of scenarios troubled by realistic imperfections. Our quantitative results, accompanied by a comprehensive reproduction package, show strong differences between QAOA variants that can be pinpointed to narrow and specific effects. We identify influential co-variables and relevant non-functional quality goals that, we argue, mark the relevant ingredients for designing appropriate software engineering abstraction mechanisms and automated tool-chains for devising quantum solutions from high-level problem specifications.}, language = {en} } @unpublished{PeriyasamyPlingeMutschleretal., author = {Periyasamy, Maniraman and Plinge, Axel and Mutschler, Christopher and Scherer, Daniel D. and Mauerer, Wolfgang}, title = {Guided-SPSA: Simultaneous Perturbation Stochastic Approximation assisted by the Parameter Shift Rule}, abstract = {The study of variational quantum algorithms (VQCs) has received significant attention from the quantum computing community in recent years. These hybrid algorithms, utilizing both classical and quantum components, are well-suited for noisy intermediate-scale quantum devices. Though estimating exact gradients using the parameter-shift rule to optimize the VQCs is realizable in NISQ devices, they do not scale well for larger problem sizes. The computational complexity, in terms of the number of circuit evaluations required for gradient estimation by the parameter-shift rule, scales linearly with the number of parameters in VQCs. On the other hand, techniques that approximate the gradients of the VQCs, such as the simultaneous perturbation stochastic approximation (SPSA), do not scale with the number of parameters but struggle with instability and often attain suboptimal solutions. In this work, we introduce a novel gradient estimation approach called Guided-SPSA, which meaningfully combines the parameter-shift rule and SPSA-based gradient approximation. The Guided-SPSA results in a 15\% to 25\% reduction in the number of circuit evaluations required during training for a similar or better optimality of the solution found compared to the parameter-shift rule. The Guided-SPSA outperforms standard SPSA in all scenarios and outperforms the parameter-shift rule in scenarios such as suboptimal initialization of the parameters. We demonstrate numerically the performance of Guided-SPSA on different paradigms of quantum machine learning, such as regression, classification, and reinforcement learning.}, language = {en} } @inproceedings{ZwingelKediliogluReitelshoeferetal., author = {Zwingel, Maximilian and Kedilioglu, Oguz and Reitelsh{\"o}fer, Sebastian and Mauerer, Wolfgang}, title = {Optimization Problems in Production and Planning: Approaches and Limitations in View of Possible Quantum Superiority}, series = {Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2023}, booktitle = {Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2023}, publisher = {Springer Nature}, isbn = {9783031740091}, language = {en} } @inproceedings{TrespUdluftHeinetal., author = {Tresp, Volker and Udluft, Steffen and Hein, Daniel and Hauptmann, Werner and Leib, Martin and Mutschler, Christopher and Scherer, Daniel D. and Mauerer, Wolfgang}, title = {Workshop Summary: Quantum Machine Learning}, series = {2023 IEEE International Conference on Quantum Computing and Engineering, Bellevue, WA, United States, September 17-22, 2023}, booktitle = {2023 IEEE International Conference on Quantum Computing and Engineering, Bellevue, WA, United States, September 17-22, 2023}, publisher = {IEEE}, doi = {10.1109/QCE57702.2023.10174}, language = {en} } @inproceedings{GogeisslSafiMauerer, author = {Gogeißl, Martin and Safi, Hila and Mauerer, Wolfgang}, title = {Quantum Data Encoding Patterns and their Consequences}, series = {Q-Data '24: Proceedings of the 1st Workshop on Quantum Computing and Quantum-Inspired Technology for Data-Intensive Systems and Applications, June 9 - 15, 2024, Santiago AA Chile}, booktitle = {Q-Data '24: Proceedings of the 1st Workshop on Quantum Computing and Quantum-Inspired Technology for Data-Intensive Systems and Applications, June 9 - 15, 2024, Santiago AA Chile}, publisher = {ACM}, isbn = {979-8-4007-0553-3}, doi = {10.1145/3665225.3665446}, pages = {27 -- 37}, abstract = {The use of quantum processing units (QPUs) promises speed-ups for solving computational problems, in particular for discrete optimisation. While a few groundbreaking algorithmic approaches are known that can provably outperform classical computers, we observe a scarcity of programming abstractions for constructing efficient quantum algorithms. A good fraction of the literature that addresses solving concrete problems related to database management concentrates on casting them as quadratic unconstrained binary optimisation problems (QUBOs), which can then, among others, be processed on gate-based machines (using the quantum approximate optimisation algorithm), or quantum annealers. A critical aspect that affects efficiency and scalability of either of these approaches is how classical data are loaded into qubits, respectively how problems are encoded into QUBO representation. The effectiveness of encodings is known to be of crucial importance for quantum computers, especially since the amount of available qubits is strongly limited in the era of noisy, intermediate-size quantum computers. In this paper, we present three encoding patterns, discuss their impact on scalability, and their ease of use. We consider the recreational (yet computationally challenging) Sudoku problem and its reduction to graph colouring as an illustrative example to discuss their individual benefits and disadvantages. Our aim is enable database researchers to choose an appropriate encoding scheme for their purpose without having to acquire in-depth knowledge on quantum peculiarities, thus easing the path towards applying quantum acceleration on data management systems.}, language = {en} } @unpublished{JungKrumkeSchrothetal., author = {Jung, Matthias and Krumke, Sven O. and Schroth, Christof and Lobe, Elisabeth and Mauerer, Wolfgang}, title = {QCEDA: Using Quantum Computers for EDA}, abstract = {The field of Electronic Design Automation (EDA) is crucial for microelectronics, but the increasing complexity of Integrated Circuits (ICs) poses challenges for conventional EDA: Corresponding problems are often NP-hard and are therefore in general solved by heuristics, not guaranteeing optimal solutions. Quantum computers may offer better solutions due to their potential for optimization through entanglement, superposition, and interference. Most of the works in the area of EDA and quantum computers focus on how to use EDA for building quantum circuits. However, almost no research focuses on exploiting quantum computers for solving EDA problems. Therefore, this paper investigates the feasibility and potential of quantum computing for a typical EDA optimization problem broken down to the Min-k-Union problem. The problem is mathematically transformed into a Quadratic Unconstrained Binary Optimization (QUBO) problem, which was successfully solved on an IBM quantum computer and a D-Wave quantum annealer.}, language = {en} } @incollection{Mauerer, author = {Mauerer, Wolfgang}, title = {Superoperators for Quantum Software Engineering}, series = {Quantum Software: Aspects of Theory and System Design}, booktitle = {Quantum Software: Aspects of Theory and System Design}, editor = {Exman, Iaakov and Perez-Castillo, Ricardo and Piattini, Mario and Felderer, Michael}, publisher = {Springer Nature}, issn = {978-3-031-64136-7}, doi = {10.1007/978-3-031-64136-7_3}, abstract = {As implementations of quantum computers grow in size and maturity, the question of how to program this new class of machines is attracting increasing attention in the software engineering domain. Yet, many questions from how to design expressible quantum languages augmented with formal semantics via implementing appropriate optimizing compilers to abstracting details of machine properties in software systems remain challenging. Performing research at this intersection of quantum computing and software engineering requires sufficient knowledge of the physical processes underlying quantum computations, and how to model these. In this chapter, we review a superoperator-based approach to quantum dynamics, as it can provide means that are sufficiently abstract, yet concrete enough to be useful in quantum software and systems engineering, and outline how it is used in several important applications in the field.}, language = {en} } @inproceedings{SafiWinterspergerMauerer, author = {Safi, Hila and Wintersperger, Karen and Mauerer, Wolfgang}, title = {Influence of HW-SW-Co-Design on Quantum Computing Scalability}, series = {2023 IEEE International Conference on Quantum Software (QSW), Chicago, IL, USA, 02-08 July 2023}, booktitle = {2023 IEEE International Conference on Quantum Software (QSW), Chicago, IL, USA, 02-08 July 2023}, publisher = {IEEE}, isbn = {979-8-3503-0479-4}, doi = {10.1109/QSW59989.2023.00022}, pages = {104 -- 115}, abstract = {The use of quantum processing units (QPUs) promises speed-ups for solving computational problems. Yet, current devices are limited by the number of qubits and suffer from significant imperfections, which prevents achieving quantum advantage. To step towards practical utility, one approach is to apply hardware-software co-design methods. This can involve tailoring problem formulations and algorithms to the quantum execution environment, but also entails the possibility of adapting physical properties of the QPU to specific applications. In this work, we follow the latter path, and investigate how key figures— circuit depth and gate count—required to solve four cornerstone NP-complete problems vary with tailored hardware properties. Our results reveal that achieving near-optimal performance and properties does not necessarily require optimal quantum hardware, but can be satisfied with much simpler structures that can potentially be realised for many hardware approaches.m Using statistical analysis techniques, we additionally identify an underlying general model that applies to all subject problems. This suggests that our results may be universally applicable to other algorithms and problem domains, and tailored QPUs can find utility outside their initially envisaged problem domains. The substantial possible improvements nonetheless highlight the importance of QPU tailoring to progress towards practical deployment and scalability of quantum software.}, language = {en} } @article{WinterspergerDommertEhmeretal., author = {Wintersperger, Karen and Dommert, Florian and Ehmer, Thomas and Hoursanov, Andrey and Klepsch, Johannes and Mauerer, Wolfgang and Reuber, Georg and Strohm, Thomas and Yin, Ming and Luber, Sebastian}, title = {Neutral Atom Quantum Computing Hardware: Performance and End-User Perspective}, series = {EPJ Quantum Technology}, volume = {10}, journal = {EPJ Quantum Technology}, publisher = {Springer Nature}, doi = {10.1140/epjqt/s40507-023-00190-1}, pages = {27}, abstract = {We present an industrial end-user perspective on the current state of quantum computing hardware for one specific technological approach, the neutral atom platform. Our aim is to assist developers in understanding the impact of the specific properties of these devices on the effectiveness of algorithm execution. Based on discussions with different vendors and recent literature, we discuss the performance data of the neutral atom platform. Specifically, we focus on the physical qubit architecture, which affects state preparation, qubit-to-qubit connectivity, gate fidelities, native gate instruction set, and individual qubit stability. These factors determine both the quantum-part execution time and the end-to-end wall clock time relevant for end-users, but also the ability to perform fault-tolerant quantum computation in the future. We end with an overview of which applications have been shown to be well suited for the peculiar properties of neutral atom-based quantum computers.}, language = {en} } @inproceedings{GreiweKruegerMauerer, author = {Greiwe, Felix and Kr{\"u}ger, Tom and Mauerer, Wolfgang}, title = {Effects of Imperfections on Quantum Algorithms}, series = {2023 IEEE International Conference on Quantum Software (QSW), Chicago, IL, USA, 02-08 July 2023}, booktitle = {2023 IEEE International Conference on Quantum Software (QSW), Chicago, IL, USA, 02-08 July 2023}, publisher = {IEEE}, doi = {10.1109/QSW59989.2023.00014}, pages = {31 -- 42}, abstract = {Quantum computers promise considerable speedups over classical approaches, which has raised interest from many disciplines. Since any currently available implementations suffer from noise and imperfections, achieving concrete speedups for meaningful problem sizes remains a major challenge. Yet, imperfections and noise may remain present in quantum computing for a long while. Such limitations play no role in classical software computing, and software engineers are typically not well accustomed to considering such imperfections, albeit they substantially influence core properties of software and systems. In this paper, we show how to model imperfections with an approach tailored to (quantum) software engineers. We intuitively illustrate, using numerical simulations, how imperfections influence core properties of quantum algorithms on NISQ systems, and show possible options for tailoring future NISQ machines to improve system performance in a co-design approach. Our results are obtained from a software framework that we provide in form of an easy-to-use reproduction package. It does not require computer scientists to acquire deep physical knowledge on noise, yet provide tangible and intuitively accessible means of interpreting the influence of noise on common software quality and performance indicators.}, language = {en} } @incollection{YueMauererAlietal., author = {Yue, Tao and Mauerer, Wolfgang and Ali, Shaukat and Taibi, Davide}, title = {Challenges and Opportunities in Quantum Software Architecture}, series = {Software Architecture: Research Roadmaps from the Community}, booktitle = {Software Architecture: Research Roadmaps from the Community}, isbn = {978-3-031-36847-9}, doi = {10.1007/978-3-031-36847-9_1}, pages = {1 -- 23}, abstract = {Quantum computing is a relatively new paradigm that has raised considerable interest in physics and computer science in general but has so far received little attention in software engineering and architecture. Hybrid applications that consist of both quantum and classical components require the development of appropriate quantum software architectures. However, given that quantum software engineering (QSE) in general is a new research area, quantum software architecture-a subresearch area in QSE is also understudied. The goal of this chapter is to provide a list of research challenges and opportunities for such architectures. In addition, to make the content understandable to a broader computer science audience, we provide a brief overview of quantum computing and explain the essential technical foundations.}, language = {en} } @inproceedings{SchoenbergerTrummerMauerer, author = {Sch{\"o}nberger, Manuel and Trummer, Immanuel and Mauerer, Wolfgang}, title = {Quantum Optimisation of General Join Trees}, series = {Joint Workshops at 49th International Conference on Very Large Data Bases (VLDBW'23) — International Workshop on Quantum Data Science and Management (QDSM'23), August 28 - September 1, 2023, Vancouver, Canada (CEUR Workshop Proceedings)}, booktitle = {Joint Workshops at 49th International Conference on Very Large Data Bases (VLDBW'23) — International Workshop on Quantum Data Science and Management (QDSM'23), August 28 - September 1, 2023, Vancouver, Canada (CEUR Workshop Proceedings)}, publisher = {RWTH Aachen, Sun SITE Central Europe}, address = {Aachen}, pages = {1 -- 12}, abstract = {Recent advances in the manufacture of quantum computers attract much attention over a wide range of fields, as early-stage quantum processing units (QPU) have become accessible. While contemporary quantum machines are very limited in size and capabilities, mature QPUs are speculated to eventually excel at optimisation problems. This makes them an attractive technology for database problems, many of which are based on complex optimisation problems with large solution spaces. Yet, the use of quantum approaches on database problems remains largely unexplored. In this paper, we address the long-standing join ordering problem, one of the most extensively researched database problems. Rather than running arbitrary code, QPUs require specific mathematical problem encodings. An encoding for the join ordering problem was recently proposed, allowing first small-scale queries to be optimised on quantum hardware. However, it is based on a faithful transformation of a mixed integer linear programming (MILP) formulation for JO, and inherits all limitations of the MILP method. Most strikingly, the existing encoding only considers a solution space with left-deep join trees, which tend to yield larger costs than general, bushy join trees. We propose a novel QUBO encoding for the join ordering problem. Rather than transforming existing formulations, we construct a native encoding tailored to quantum systems, which allows us to process general bushy join trees. This makes the full potential of QPUs available for solving join order optimisation problems.}, language = {en} } @inproceedings{UotilaGroppeGruenwaldetal., author = {Uotila, Valter and Groppe, Sven and Gruenwald, Le and Lu, Jiaheng and Mauerer, Wolfgang}, title = {Preface QDSM}, series = {Joint Workshops at 49th International Conference on Very Large Data Bases (VLDBW'23) — International Workshop on Quantum Data Science and Management (QDSM'23), August 28 - September 1, 2023, Vancouver, Canada (CEUR Workshop Proceedings)}, booktitle = {Joint Workshops at 49th International Conference on Very Large Data Bases (VLDBW'23) — International Workshop on Quantum Data Science and Management (QDSM'23), August 28 - September 1, 2023, Vancouver, Canada (CEUR Workshop Proceedings)}, publisher = {RWTH Aachen, Sun SITE Central Europe}, address = {Aachen}, abstract = {The first international workshop on Quantum Data Science and anagement (QDSM), co-located with VLDB 2023, is centered around addressing the possibilities of quantum computing for data science and data management. Quantum computing is a relatively new and emerging field that is believed to have huge computational potential in the future. In the QDSM workshop, we want to provide a venue for discussing and publishing novel results of applying quantum computing to hard data science and data management problems. These problems include join order optimization, designing efficient quantum feature maps, studying possibilities of solving linear programs with quantum algorithms, and divergent index tuning with quantum machine learning. Besides, we include a short and visionary survey on quantum computing for databases. Theworkshop provides a platform for active discussion on these and related topics.}, language = {en} } @inproceedings{JoblinApelHunsenetal., author = {Joblin, Mitchell and Apel, Sven and Hunsen, Claus and Mauerer, Wolfgang}, title = {Classifying Developers into Core and Peripheral: An Empirical Study on Count and Network Metrics}, series = {2017 IEEE/ACM 39th International Conference on Software Engineering (ICSE), Buenos Aires, Argentina, 20-28 May 2017}, booktitle = {2017 IEEE/ACM 39th International Conference on Software Engineering (ICSE), Buenos Aires, Argentina, 20-28 May 2017}, publisher = {IEEE}, doi = {10.1109/icse.2017.23}, pages = {164 -- 174}, abstract = {Knowledge about the roles developers play in a software project is crucial to understanding the project's collaborative dynamics. In practice, developers are often classified according to the dichotomy of core and peripheral roles. Typically, count-based operationalizations, which rely on simple counts of individual developer activities (e.g., number of commits), are used for this purpose, but there is concern regarding their validity and ability to elicit meaningful insights. To shed light on this issue, we investigate whether count-based operationalizations of developer roles produce consistent results, and we validate them with respect to developers' perceptions by surveying 166 developers. Improving over the state of the art, we propose a relational perspective on developer roles, using fine-grained developer networks modeling the organizational structure, and by examining developer roles in terms of developers' positions and stability within the developer network. In a study of 10 substantial open-source projects, we found that the primary difference between the count-based and our proposed network-based core-peripheral operationalizations is that the network-based ones agree more with developer perception than count-based ones. Furthermore, we demonstrate that a relational perspective can reveal further meaningful insights, such as that core developers exhibit high positional stability, upper positions in the hierarchy, and high levels of coordination with other core developers, which confirms assumptions of previous work.}, language = {en} } @inproceedings{JoblinMauererApeletal., author = {Joblin, Mitchell and Mauerer, Wolfgang and Apel, Sven and Siegmund, Janet and Riehle, Dirk}, title = {From Developer Networks to Verified Communities: A Fine-Grained Approach}, series = {2015 IEEE/ACM 37th IEEE International Conference on Software Engineering, 16-24 May 2015, Florence, Italy}, booktitle = {2015 IEEE/ACM 37th IEEE International Conference on Software Engineering, 16-24 May 2015, Florence, Italy}, publisher = {IEEE}, isbn = {978-1-4799-1934-5}, doi = {10.1109/icse.2015.73}, pages = {563 -- 573}, abstract = {Effective software engineering demands a coordinated effort. Unfortunately, a comprehensive view on developer coordination is rarely available to support software-engineering decisions, despite the significant implications on software quality, software architecture, and developer productivity. We present a fine-grained, verifiable, and fully automated approach to capture a view on developer coordination, based on commit information and source-code structure, mined from version-control systems. We apply methodology from network analysis and machine learning to identify developer communities automatically. Compared to previous work, our approach is fine-grained, and identifies statistically significant communities using order-statistics and a community-verification technique based on graph conductance. To demonstrate the scalability and generality of our approach, we analyze ten open-source projects with complex and active histories, written in various programming languages. By surveying 53 open-source developers from the ten projects, we validate the authenticity of inferred community structure with respect to reality. Our results indicate that developers of open-source projects form statistically significant community structures and this particular view on collaboration largely coincides with developers' perceptions of real-world collaboration.}, language = {en} }