Hallo, hier ein Quantum Clock talk aus Innsbruck, online zugänglich falls wer intresesse hat. Ich habe den Namen mal notiert, dass man nach veröffentlichung dem eine Werbemail schicken kann, er arbeitet mit Zoller, Hammerer etc. Grüße Enno -------- Weitergeleitete Nachricht -------- Betreff: [COST Action RQI - WG2] Online Seminar Thursday, 18th of June 10:00 CEST - Torsten Zache - Non-local mass superpositions and optical clock interferometry in atomic ensemble quantum networks Datum: Sun, 14 Jun 2026 22:57:38 +0100 Von: Dennis Rätzel <dennis.raetzel@zarm.uni-bremen.de> Dear Members of Working Group WG2, I would like to invite you to the next talk of our online seminar. Date and time: Thursday, 18th of June 10:00 CEST Speaker: Torsten Zache, Universität Innsbruck, Austria Title: Non-local mass superpositions and optical clock interferometry in atomic ensemble quantum networks Abstract: Quantum networks are emerging as powerful platforms for sensing, communication, and fundamental tests of physics. We propose a programmable quantum sensing network based on entangled atomic ensembles, where optical clock qubits realize mass superpositions arising via mass-energy equivalence, as in atom and atom-clock interferometry. Our approach uniquely combines scalability to large atom numbers with minimal control requirements, relying only on collective addressing of internal atomic states. This enables the creation of both non-local and local superpositions with spatial separations beyond those achievable in conventional matter-wave interferometry with single atoms. Starting from Bell-type seed states distributed via photonic channels, collective operations within atomic ensembles coherently build many-body mass superpositions sensitive to gravitational redshift. The resulting architecture implements a non-local Ramsey interferometer, where gravitationally induced phase shifts are imprinted on non local entangled states and are read out through local measurements at the network nodes. Beyond extending the spatial reach of mass superpositions, our scheme establishes a scalable, programmable platform to probe the interface of quantum mechanics and gravity, and offers a new experimental pathway to test atom and atom-clock interferometer proposals, e.g. for probing gravitational dephasing, in a network-based quantum laboratory. The talk will be streamed via Zoom https://uni-bremen.zoom-x.de/j/67290871943?pwd=o98aQfS9g6iItJDvj93QC3ZP3az8P... I am looking forward to seeing you for the talk and the subsequent discussion with Torsten Zache. With kind regards, Dennis (Rätzel) University College London WG2 leader