Macroscopic quantum coherent phenomena in Bose Josephson junctions
type: Dataset
description: In recent years, cold atomic systems have been recognized as very promising tools for quantum simulators and for applications in quantum technology. In particular, a Bose Josephson junction (BJJ) - a system of ultracold dilute bosons which can occupy two modes - has been used to realize an atomic interferometer, allowing to estimate a phase shift with a precision beyond the classical limit. In this thesis we study theoretically the production, detection and decoherence of entangled states which can be used for high-precision interferometry in a Bose Josephson junction. Among such useful quantum states are atomic squeezed states and macroscopic superpositions of coherent states. In the first part of the thesis, after demonstrating that macroscopic superpositions of coherent states can be created during the dynamics following a "quench" of the coupling between the two modes of the junction, we study protocols for their experimental detection. In the experiments there are unavoidable sources of noise, the major sources being phase noise, induced by stochastic fluctuations of the energies of the two modes of the BJJ, and particle losses. The presence of noise induces decoherence and degrades the quantum correlations of these states. In the second part of the thesis we analyze in detail how the useful quantum correlations of squeezed states and macroscopic superpositions are degraded by phase noise. We show that for moderate phase noise intensities multicomponent superpositions of coherent states are interesting candidates for high-precision atom interferometry. Finally, we address the effect of atom losses on the formation of macroscopic superpositions, showing how decoherence affects the system density matrix.
identifier: NNT: 2011GRENY066
issued: 2026-05-24T08:18:05.005499
language: fr
modified: 2026-05-24T08:18:05.005505
contact point: Organization
  fn: CCSD
keyword: atomes-froids
keyword: coherence-quantique
keyword: cold-atoms
keyword: infoeu-reposemanticsdoctoralthesis
keyword: josephson
keyword: physcondcm-genphysics-physicscondensed-matter-cond-matother-cond-matother
keyword: quantum-coherence
keyword: theses
landing page: https://theses.hal.science/tel-00680099

Macroscopic quantum coherent phenomena in Bose Josephson junctions
type: Distribution
format: HTML
issued: 2026-05-24T08:18:05.052015
modified: 2026-05-24T08:18:04.980752
access URL: https://theses.hal.science/tel-00680099

test_moissonnage_selune
type: Agent