Graeme Milton, University of Utah

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Professor Graeme Milton, University of Utah, will give a seminar entitled "Cloaking : where science meets science fiction" on Friday, September 16 at 11h00 in the Pierre Cotton room

"Cloaking : where science meets science fiction"

Abstract :
The possibility of invisibility has captured imaginations : think of the invisible man, the invisible woman, the invisible Aston Martin of James Bond, Star Trek and Harry Potter. Camouflage and stealth technology achieve partial invisibility, but can one achieve true invisibility ? Scientific interest in this subject has been spurred by some exciting developments over the past decade. In transformation based cloaking, the cloaking device is a shell placed around the object which guides light around it. It is as if space is warped in the shell around the object, but this warping is caused not by a real stretching of space, but rather by a careful choice of material properties in the shell. This can be extended to acoustics, but bending the sound in the required way requires novel materials whose inertia depends on the direction of oscillation, and such materials can be designed.

Perhaps more intriguing are the exterior cloaking methods we have been developing : the cloaking device now lies outside the object to be cloaked and cloaking is achieved through destructive interference caused by waves generated by the cloaking device, which however do not propagate very far due to their evanescent character. Most spectacular is cloaking due to anomalous resonance. Unlike normal resonance where one approaches a pole of the response function, and the length scale of oscillations is set by the associated eigenmode, anomalous response is associated with essential singularities of the response function and the length scale of oscillations is set by how close one is to resonance.