Guest editorial: Selected extended papers from the Quantum Software Architecture Workshop at IEEE International Conference on Software Architecture 2021 (ICSA 2021)

At a fast pace, applications of quantum algorithms are being built by industrial and academic users to gain experiences with this quickly evolving technology. The more these endeavours shifting from an experimental stage towards solving real practical problems, it becomes clear that systematic approach is needed develop the corresponding applications. This need based on fact software involves computers very different classical software. Such for building must especially consider early phases development process addressing architecture Guidelines successful missing research in domain has just begun. Questions be answered include, example, which architectural style should followed, or whether there already established best practices? Real-world most often hybrid—that is, application consists circuits as well programs. implies means having solve integration problem. For decades, such problems addressed workflow technology, implying first hybrid A circuit processes data expects states. states can prepared using any multitude approaches each pros cons. knowledge about solutions presented patterns, indicating relevance pattern languages Running individual appropriate initial experiments algorithms. But when used production, issues scalability, availability, security, appear. Furthermore, not assumed all developed scratch. Instead, existing reused much possible accelerate benefitting potential speedups enhanced precision purpose, methods re-factoring applications, needed. articles special issue partly contributions 1st Workshop Quantum Software Architecture. goal workshop was bring together researchers practitioners areas computing (classical) help shaping community discuss like ones mentioned above. also proposed several questions lifecycle developing how test implemented software, migrate proof concepts productive systems, automate deployment specify KPIs measuring quality solutions. Two keynotes delivered industry leaders completed program kicked off further discussions. Four papers have been selected issue. Three them extended versions submissions adding insights into original publication. ‘Encoding Patterns Algorithms’ Manuela Weigold Marie Salm. Extensions language under construction suggested paper. Additional encoding patterns described. supports understanding (potentially severe) consequences state preparation overall algorithm may diminish speedup. ‘Analysis Hybrid Network classification tasks’ Gerhard Hellstern. quantum-classical neural network finance MNIST second article. Compared pure network, author reports performance advantages but observes, at same time, overfitting net. ‘QuaSiMo: Composable Library Program Workflows Simulation’ Thien Nguyen et al. composable programming scheme workflows simulations next contribution. expressive set structures constructed accompanied new enabling complex ‘QProv: Provenance System Computing’ Benjamin Weder final paper focusses provenance: identifies information relevant concrete devices. provenance system sketched automatically collects identified prepares uniform manner database. There no conflict interest. Johanna Barzen leads Computing Digital Humanities area Institute Architecture Application Systems (IAAS). Her lies intersection computer science, media digital humanities, computing. Thereby, she applies languages, analytics, machine learning. Since 2012, working humanities projects MUSE method along supporting tool chain identify costume films. interdisciplinary combining potentials coined term Humanities. Ongoing (quantum) learning currently determining contrast approaches. Currently, visiting scientist Business Informatics Group TU-Wien bridging area’s model-driven humanities. Sebastian Feld assistant professor Delft University Technology, Netherlands. He part & Computer Engineering department, where he his group Machine Learning. investigate technology might creating near-term techniques assist scalable Before, head Applications Research Laboratory (QAR-Lab) LMU Munich. His main focus postdoctoral researcher optimisation quantum-assisted artificial intelligence. earned doctorate Munich planning alternative routes, time series analysis geospatial trajectories. Frank Leymann full science founder (IAAS) Stuttgart, Germany. interests include large middleware, funded European Union, German Government, directly partners. co-author 500 peer-reviewed papers, than 70 granted patents, standards. Before moving university, served Distinguished Engineer IBM. Karoline Wild received Master Science degree Information Stuttgart Hohenheim 2016. works associate multi-cloud management, focussing distribution fragments their cross-cloud communication behaviour.