Junior Quantum Seminar

Please join us for the Junior Quantum Seminar with Shreyas S. Joglekar from the Laboratory of Nanoscale Magnetic Materials and Magnonics (EPFL), who will give the talk "Spin wave assisted magnetization switching of nanomagnet memory bits" and Chufan Zhou from the Advanced Quantum Architecture Laboratory (EPFL) who will give the talk "Planar 16-band metasurface-enhanced spectral filter for integrated image sensing" on Tuesday October 29th from 9h30-11h.

PLEASE NOTE: The Junior Quantum Series are for gathering  the junior quantum community of master's students, PhDs and post-docs at EPFL, to create a non-judgmental space were scientific ideas can be shared between peers. This event is not for Professors or senior researchers. 

ABSTRACT :
1. Spin wave assisted magnetization switching of nanomagnet memory bits:
Spin waves or their quasi-particles known as magnons are promising candidates to realize in-memory computing hardware. Propagating magnons coherently excited via microwave irradiation in a thin film Yttrium Iron Garnet (YIG) possess large decay lengths over hundreds of micrometers, low-loss transmission, complex interconnectivity and rich nonlinear phenomena. Leveraging these properties along with the recently discovered memory functionality, magnon-based computing platforms can offer an energy efficient hardware platform for AI algorithms. In this talk, I will focus on how magnons excited in YIG thin film can be stored in nonvolatile manner by switching the magnetization of differently shaped Ni81Fe19 nanomagnet memory bits having widths down to 50 nm. The talk will encompass various characterization techniques to readout the magnetic state of nanomagnet bits such as Vector Network Analyzer, Magnetic Force Microscopy, Microfocus Brillouin Light Scattering spectroscopy and Scanning Transmission X-ray Microscopy.
2. Planar 16-band metasurface-enhanced spectral filter for integrated image sensing:
We study theoretically and demonstrate experimentally a 16-band narrow band wavelength selective filter in the near-infrared range. The combination of a pair of distributed Bragg reflectors with a sub-wavelength grating metasurface embedded in the intra-cavity provides a narrow response which can be tuned by adjusting the geometry of the sub-wavelength grating metasurface. The key advantage of this approach is its ease of fabrication, where the spectral response is tuned by merely changing the grating period, resulting in a perfectly planar geometry that can be easily integrated with a broad variety of photodetectors, thus enabling attractive applications such as bio-imaging, time-of-flight sensors and LiDAR. The experimental results are supported by numerical simulations and effective medium theory that unveil the mechanisms that lead to the optical response of the device. It is also shown how the polarization dependence of the structure can be used to determine very accurately the polarization of incoming light.

BIO:
1. Shreyas S. Joglekar is a PhD student at EPFL working on spin wave-based memory device. He obtained bachelor’s degree in Metallurgical Engineering from College of Engineering Pune, India and received MSc in Materials Science and Engineering at EPFL. He worked on metal additive manufacturing at Empa and on the growth of II-V and III-V semiconductor nanostructures at the Laboratory of Semiconductor Materials (LMSC) before undertaking a doctoral research at LMGN.
2. Chufan Zhou is a PhD student from AQUA lab. Her research interested in wavelength selective filter and metasurface enhanced polarization imaging. She is frequent traveler and experienced baker.