arXiv subjects

Pawel Wójcik

Publications and source records attributed to Pawel Wójcik.

3 recordsLinked to original sources

arXiv2026

Spin Hall and Edelstein effects in a ballistic quantum dot with Rashba spin-orbit coupling

We study spin-resolved transport in a ballistic quantum dot with Rashba spin-orbit coupling, focusing on charge-to-spin conversion and spin Hall effect. In the regime where the dot size is comparable to the Fermi wavelength, we identify a clear crossover from weak localization to weak antilocalization as the Rashba coupling increases. This transition is accompanied by gate-tunable spin currents of Edelstein and spin Hall type, whose behavior reflects the underlying electron wavefunction interference. Notably, the Edelstein current shows an inflection point at the critical Rashba strength, signaling the crossover from weak localization to weak antilocalization. In the presence of an in-plane magnetic field we also report a transition in angular periodicity of the magnetoresistance -- from $π$ to $2π$ -- arising from the interplay between spin-orbit interaction and Zeeman coupling. These results establish a direct link between quantum coherence, charge-to-spin conversion, and geometric confinement in mesoscopic systems.

cond-mat.mes-hall↗

arXiv2024

How Do Microservice API Patterns Impact Understandability? A Controlled Experiment

Microservices expose their functionality via remote Application Programming Interfaces (APIs), e.g., based on HTTP or asynchronous messaging technology. To solve recurring problems in this design space, Microservice API Patterns (MAPs) have emerged to capture the collective experience of the API design community. At present, there is a lack of empirical evidence for the effectiveness of these patterns, e.g., how they impact understandability and API usability. We therefore conducted a controlled experiment with 6 microservice patterns to evaluate their impact on understandability with 65 diverse participants. Additionally, we wanted to study how demographics like years of professional experience or experience with MAPs influence the effects of the patterns. Per pattern, we constructed two API examples, each in a pattern version "P" and a functionally equivalent non-pattern version "N" (24 in total). Based on a crossover design, participants had to answer comprehension questions, while we measured the time. For five of the six patterns, we identified a significant positive impact on understandability, i.e., participants answered faster and / or more correctly for "P". However, effect sizes were mostly small, with one pattern showing a medium effect. The correlations between performance and demographics seem to suggest that certain patterns may introduce additional complexity; people experienced with MAPs will profit more from their effects. This has important implications for training and education around MAPs and other patterns.

cs.SE↗

arXiv2018

Symmetry of Birkhoff-James orthogonality of operators defined between infinite dimensional Banach spaces

We study left symmetric bounded linear operators in the sense of Birkhoff-James orthogonality defined between infinite dimensional Banach spaces. We prove that a bounded linear operator defined between two strictly convex Banach spaces is left symmetric if and only if it is zero operator when the domain space is reflexive and Kadets-Klee. We exhibit a non-zero left symmetric operator when the spaces are not strictly convex. We also study right symmetric bounded linear operators between infinite dimensional Banach spaces.

math.FA↗