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Events: Special Seminars

  • Chaotic Markers in <em>C. elegans</em>

    Guest: Dr. Jenny Magnes, Vassar College
    Thursday, March 12, 2020 2:00 pm - 3:00 pm
    Location: CSP Conference Room (322)

    In a dynamic far-field diffraction experiment, we use the optical fluctuations in the diffraction pattern to calculate the largest Lyapunov exponent to characterize the locomotory predictability of an oversampled microscopic species. We use a live nematode, Caenorhabditis elegans, as a model organism to demonstrate our method. One point in the visible diffraction pattern allows for the monitoring of the relative phase of all points on the nematode in time. This single time-series displays chaotic markers in the locomotion of the Caenorhabditis elegans by reconstructing the multidimensional phase space. The average largest Lyapunov exponent (base e) associated with the dynamic diffraction of ten adult wildtype (N2) Caenorhabditis elegans is 1.443 +- 0.040 1/s.

    Traditionally, the locomotion of microscopic species is studied through visual inspection under a microscope which is often combined with video analysis . There are several benefits in diffraction studies that provide information complementary to classical microscopy. Diffraction allows the species to be probed in more natural environments than conventional microscopy because diffraction is tied to an image plane. Another feature of diffraction microscopy is rooted in subtle changes in the plasticity of the object that can be detected to less than a wavelength without a microscope. Diffraction microscopy complements traditional microscopy by using light to process information embedded in the structure of the species hence saving computing power. Fraunhofer diffraction lends itself to optically process data through diffraction as the pattern evolves in time which can produce a single time series by probing a point in the diffraction pattern. Consequently, the time series contains information about the time evolution of every single point outlining the object. In this work, we demonstrate that condensing locomotion optically into a single time-series allows for the use of readily available complex systems tools.

  • Systems Engineering for Superconducting Quantum Computing

    Guest: Prof. Matteo Mariantoni, Institute for Quantum Computing, Univ. Of Waterloo.
    Tuesday, April 17, 2018 4:30 pm - 5:30 pm
    Location: CSP Conference Room (322)

    I will provide a brief introduction to the main technological and scientific challenges to be faced in order to build a practical quantum computer, with emphasis on the case of superconducting quantum computing. I will then delve into a detailed explanation of a method to address the wiring of a two-dimensional array of superconducting quantum bit (qubits): The quantum socket. Next, I will show how the quantum socket can be extended to a medium-scale quantum computer and how it can help mitigate coherent leakage errors due to qubits interacting with spurious cavity modes. I will then show thermocompression bonding technology, a method that allows us to further protect qubits from the environment. In particular, I will propose a new qubit design based on our experimental implementation of thermocompression bonded chips, where vacuum gap capacitors are used to reduce dissipation due to so-called two-level state defects in amorphous dielectrics, which are the insulators presently use in our qubits.

  • LOPA-based direct laser writing of multi-dimensional & multi-functional photonic structures

    Guest: Prof. Diep Lai, The Quantum and Molecular Photonics Laboratory (LPQM), Cachan, France
    Friday, February 3, 2017 2:00 pm - 3:00 pm
    Location: CSP Conference Room (322)

    We have developed a simple and low-cost fabrication technique, based on low one-photon absorption (LOPA) phenomena in a weakly absorbing photoresist (532 nm laser versus SU8 or S18 photoresist)[1,2,3]. This novel approach enables production of submicrometer 2D and 3D structures and could allow for imaging of submicrometer structures in 3D using a very modest laser power. This technique is also demonstrated as a simple technique to couple a single nanoparticle (nonlinear, metallic, or fluorescent) to polymer-based photonic structures [4,5]. It is recently demonstrated that the LOPA based direct laser writing also allowed to realize as desired plasmonic (gold) and magneto-photonic (Fe3O4) nanostructures [6,7]. Different applications of these fabricated structures could be envisioned, and partially realized, such as tuneable photonic devices, data storage, bright single photon source, quantum information, plasmonic data storage, color nanoprinter.

    1. M. T. Do, et al., Submicrometer 3D structures fabrication enabled by one-photon absorption direct laser writing, Opt. Express 21, 20964-20973 (2013).

    2. D. T. T. Nguyen, et al., One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect, J. Appl. Phys. 119, 013101 (2016).

    3. Q. C. Tong, et al., Direct laser writing of polymeric nanostructures via optically induced local thermal effect, Appl. Phys. Lett. 108, 183104 (2016).

    4. M. T. Do, et al., Controlled coupling of a single nanoparticle in polymeric microstructure by low one-photon absorption-based direct laser writing technique, Nanotechnology 26, 105301 (2015).

    5. D. T. T. Nguyen, et al., Coupling of a single active nanoparticle to a polymer-based photonic structure, J. Science: Advanced Materials and Devices 1, 18-30 (2016).

    6. Q. C. Tong, et al., Rapid direct laser writing of desired plasmonic nanostructures, Submitted (2017).

    7. T. H. Au, et al., Direct laser writing of magneto-photonic sub-microstructures, Submitted (2016).

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