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SUMMARY:Fast scattering-matrix solver using augmented partial factorizatio
 n - Wade Hsu (University of Southern California)
DTSTART:20230322T103000Z
DTEND:20230322T110000Z
UID:TALK195679@talks.cam.ac.uk
DESCRIPTION:The scattering matrix fully characterizes the response of a co
 mplex medium\, but its computation requires solving the inhomogeneous wave
  equation for numerous inputs\, which is slow and currently can only be do
 ne for relatively small systems. We introduce the "augmented partial facto
 rization" (APF) method\, which directly computes the full scattering matri
 x without solving for unnecessary field profiles and without a loop over t
 he inputs [1]. APF is a full-wave method applicable to any complex structu
 re\, with no approximation beyond discretization. Using APF\, the full sca
 ttering matrix of a 500-wavelength-by-100-wavelength dense disordered syst
 em can be computed within 3 minutes using one CPU\, which is 1\,000 to 30\
 ,000\,000 times faster than existing methods. We have made this code open 
 source [2]. We use APF to demonstrate two-photon coherent backscattering f
 rom disorder [3]\, open channel for 3D vectorial waves [4]\, non-invasive 
 imaging deep inside disorder through scattering matrix tomography [5]\, an
 d the inverse design of nonlocal metasurfaces [6].\n[1] H.-C. Lin\, Z. Wan
 g\, and C. W. Hsu\, Nature Computational Science 2\, 815&ndash\;822 (2022)
 [2] https://github.com/complexphoton/MESTI.m[3] M. Safadi\, O. Lib\, H.-C.
  Lin\, C. W. Hsu\, A. Goetschy\, and Y. Bromberg. Nature Physics (2023) ht
 tps://doi.org/10.1038/s41567-022-01895-3.[4] H.-C. Lin and C. W. Hsu\, in 
 preparation.[5] Z. Wang\, Y. Zhang\, and C. W. Hsu\, in preparation.[6] S.
  Li\, H.-C. Lin\, and C. W. Hsu\, in preparation.
LOCATION:Seminar Room 1\, Newton Institute
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