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Bruno Ortega Goes presents

 Exactly modeling the unitary dynamics of quantum interfaces with collision models

Monday, November 13th 2023 at 10:00 am

Seminar room – Building A – CNRS

Link visio: https://univ-grenoble-alpes-fr.zoom.us/j/98048032137?pwd=eUJTV2swUi81aEdDUkJwa3U4NGVHdz09

The defence will be in English.


Abstract: Quantum interfaces are ubiquitous in quantum technologies as they allow the implementation of several functionalities including quantum memories, quantum repeaters, photonic gates, and highly entangled photonic state generation. Based on the coherent coupling between quantum emitters and propagating pulses of light, they can be realized on a large variety of experimental platforms where quantum non-demolition measurements, entanglement generation, and efficient production of non-classical resources have been reported.
This thesis explores the potential of so-called collision models to model exactly the light-matter dynamics in various kinds of quantum interfaces, providing direct access to their joint entangled states. It allows us to derive analytic expressions of the device performance, whether operated as a measuring apparatus or a source of cluster states. Since our model captures light and matter as a closed system, it verifies global energy conservation, providing access to the energy budget associated with the execution of the quantum task.
Initially, we review the theoretical foundation for quantum measurements and introduce figures of merit used throughout the thesis. Subsequently, we review the collision model method, which is based on waveguide quantum electrodynamics (WGQED), setting the stage for subsequent analyses. Then, we investigate the possibility of performing a non-destructive spin state measurement by limiting the energy budget to at most one photon. We compare the performance of two different fields: coherent field and number state superposition. We demonstrate better performance of the latter in entanglement generation, thus providing a quantum advantage. Lastly, our analysis extends to technological applications. We propose a photon-photon gate, conduct a thorough error analysis, and perform the modeling of cutting-edge experiments envisioning the deterministic generation of highly entangled states of light.