72 research outputs found
Leveraging Chaos for Wave-Based Analog Computation: Demonstration with Indoor Wireless Communication Signals
In sight of fundamental thermal limits on further substantial performance
improvements of modern digital computational processing units, wave-based
analog computation is becoming an enticing alternative. A wave, as it
propagates through a carefully tailored medium, performs the desired
computational operation. Yet, the necessary designs are so intricate that
experimental demonstrations will necessitate further technological advances.
Here, we show that, counterintuitively, the carefully tailored medium can be
replaced with a random medium, subject to an appropriate shaping of the
incident wave front. Using tunable metasurface reflect-arrays, we demonstrate
our concept experimentally in a chaotic microwave cavity. We conclude that
off-the-shelf wireless communication infrastructure in combination with a
simple reflect-array suffices to perform analog computation with Wi-Fi waves
reverberating in a room.Comment: 13 pages including 5 figures + 7 pages Supplemental Materia
Far field subwavelength imaging and focusing using a wire medium based resonant metalens
This is the second article in a series of two dealing with the concept of
"resonant metalens" we introduced recently [Phys. Rev. Lett. 104, 203901
(2010)]. It is a new type of lens capable of coding in time and radiating
efficiently in the far field region sub-diffraction information of an object. A
proof of concept of such a lens is performed in the microwave range, using a
medium made out of a square lattice of parallel conducting wires with finite
length. We investigate a sub-wavelength focusing scheme with time reversal and
demonstrate experimentally spots with focal widths of {\lambda}/25. Through a
cross-correlation based imaging procedure we show an image reconstruction with
a resolution of {\lambda}/80. Eventually we discuss the limitations of such a
lens which reside essentially in losses
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