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Quantum technologies

Dieter Meschede's research group
Home Group members Sutapa Ghosh
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Group members
M.Sc. Sutapa Ghosh
Last position
in our group:
PhD student
Field of research
in our group:
Fibre cavity QED
 
 

Publications(up to 2017)

  • M. Martinez-Dorantes, W. Alt, J. Gallego, S. Ghosh, L. Ratschbacher, Y. Völzke and D. Meschede
    Fast Nondestructive Parallel Readout of Neutral Atom Registers in Optical Potentials, Phys. Rev. Lett. 119, 180503 (2017)arXivBibTeXPDF
    ABSTRACT »

    We demonstrate the parallel and nondestructive readout of the hyperfine state for optically trapped 87Rb atoms. The scheme is based on state-selective fluorescence imaging and achieves detection fidelities > 98% within 10 ms, while keeping 99% of the atoms trapped. For the readout of dense arrays of neutral atoms in optical lattices, where the fluorescence images of neighboring atoms overlap, we apply a novel image analysis technique using Bayesian inference to determine the internal state of multiple atoms. Our method is scalable to large neutral atom registers relevant for future quantum information processing tasks requiring fast and nondestructive readout and can also be used for the simultaneous readout of quantum information stored in internal qubit states and in the atoms’ positions.

  • J. Gallego, S. Ghosh, S. K. Alavi, W. Alt, M. Martinez-Dorantes, D. Meschede and L. Ratschbacher
    High Finesse Fiber Fabry-Perot Cavities: Stabilization and Mode Matching Analysis, Appl. Phys. B 122, 47 (2016)arXivBibTeXPDF
    ABSTRACT »

    Fiber Fabry-Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications, where they typically require precise stabilization of their optical resonances. Here, we study two different approaches to construct fiber Fabry-Perot resonators and stabilize their length for experiments in cavity quantum electrodynamics with neutral atoms. A piezo-mechanically actuated cavity with feedback based on the Pound-Drever-Hall locking technique is compared to a novel rigid cavity design that makes use of the high passive stability of a monolithic cavity spacer and employs thermal self-locking and external temperature tuning. Furthermore, we present a general analysis of the mode matching problem in fiber Fabry-Perot cavities, which explains the asymmetry in their reflective line shapes and has important implications for the optimal alignment of the fiber resonators. Finally, we discuss the issue of fiber-generated background photons. We expect that our results contribute towards the integration of high-finesse fiber Fabry-Perot cavities into compact and robust quantum-enabled devices in the future.