Bose-Einstein Condensation of Photons versus Lasing and Hanbury Brown-Twiss Measurements with a Condensate of Light

The advent of controlled experimental accessibility of Bose-Einstein condensates, as realized with e.g. cold atomic gases, exciton-polaritons, and more recently photons in a dye-filled optical microcavity, has paved the way for new studies and tests of a plethora of fundamental concepts in quantum physics. We here describe recent experiments studying a transition between laser-like dynamics and Bose-Einstein condensation of photons in the dye microcavity system. Further, measurements of the second-order coherence of the photon condensate are presented. In the condensed state we observe photon number fluctuations of order of the total particle number, as understood from effective particle exchange with the photo-excitable dye molecules. The observed intensity fluctuation properties give evidence for Bose-Einstein condensation occurring in the grand-canonical statistical ensemble regime

The Future of Digital Platform Design - The Case of the EU Platform Regulation Discourse

Digital platform research focuses on the mechanisms in digital platform ecosystems and the dynamics between platform owners, complementors, and end-users. Recent studies begin looking beyond the boundaries of narrow platform ecosystems. The development of the European Union’s Digital Markets Act (DMA) is a revelatory case to study this wider perspective of ecosystems and its dynamics. Hundreds of actors participated in discourses on the regulation, which aims to regulate so-called gatekeeper platforms that are alleged to be powerful, unfair to platform users, and incontestable for competitors. By means of a critical discourse analysis, we coded 1720 contributions on the proposed and adopted DMA between June 2020 and July 2022. We identify 72 positions and 16 narratives along 5 discourses. Our study creates a better understanding of a wider perspective of platform ecosystem structure that goes beyond the triangle of platform owner, complementors, and end users

Observation of a topological edge state stabilized by dissipation

Robust states emerging at the boundary of a system constitute a hallmark for topological band structures. Other than in closed systems, topologically protected states can occur even in systems with a trivial band structure, if exposed to suitably modulated losses. Here, we study the dissipation-induced emergence of a topological band structure in a non-Hermitian one-dimensional lattice system, realized by arrays of plasmonic waveguides with tailored loss. We obtain direct evidence for a topological edge state that resides in the center of the band gap. By tuning dissipation and hopping, the formation and breakdown of an interface state between topologically distinct regions is demonstrated.Comment: 9 pages, 6 figure

The global oceanic freshwater cycle : a state-of-the-art quantification

Author Posting. © Sears Foundation for Marine Research, 2010. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 68 (2010): 569-595, doi:10.1357/002224010794657164.The current capabilities of quantifying the oceanic freshwater cycle are shown based on new observations from satellite data and re-analysis models for evaporation and precipitation over the ocean. For this purpose, we analyze the homogeneity and internal consistency of eight evaporation and seven precipitation products. Discontinuities are found around 1987 for all datasets, attributable to the launch of a microwave imaging satellite. Based on a review of comparisons with independent data and these analyses, the Global Precipitation Climatology Project (GPCP) and the Objectively Analyzed Ocean-Atmosphere Fluxes (OAFlux) evaporation product are combined with a state-of-the-art river discharge dataset to produce a new estimate of the global oceanic freshwater cycle for 1987-2006. The annual mean precipitation into the ocean averaged over 19 years is estimated at 12.2±1.2 Sv, the evaporative loss at 13.0±1.3 Sv, and the total freshwater input from land at 1.25±0.1 Sv. The oceanic budget closes within the errors estimated for each data set with an imbalance of 0.5±1.8 Sv. Based on this quantification, the global patterns of oceanic freshwater fluxes are described and a global mean is integrated to provide estimates of freshwater fluxes between basins. We find the Atlantic to be less evaporative and the Pacific less precipitative than previous in-situ estimates.The authorswould like to acknowledge support from the National Science Foundation, grant #OCE-0647949