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2Physics Quote:
"Can photons in vacuum interact? The answer is not, since the vacuum is a linear medium where electromagnetic excitations and waves simply sum up, crossing themselves with no interaction. There exist a plenty of nonlinear media where the propagation features depend on the concentration of the waves or particles themselves. For example travelling photons in a nonlinear optical medium modify their structures during the propagation, attracting or repelling each other depending on the focusing or defocusing properties of the medium, and giving rise to self-sustained preserving profiles such as space and time solitons or rapidly rising fronts such as shock waves." -- Lorenzo Dominici, Mikhail Petrov, Michal Matuszewski, Dario Ballarini, Milena De Giorgi, David Colas, Emiliano Cancellieri, Blanca Silva Fernández, Alberto Bramati, Giuseppe Gigli, Alexei Kavokin, Fabrice Laussy, Daniele Sanvitto. (Read Full Article: "The Real-Space Collapse of a Two Dimensional Polariton Gas" )

Monday, March 12, 2007

Interferometric Detection of Gravitational Waves:
5 Needed Breakthroughs -- Seiji Kawamura

Seiji[ In our ongoing feature '5-Breakthroughs', so far most of our guests were from the exciting field of research on detection of gravitational waves. It started with David Shoemaker of LIGO and we also had Jean-Yves Vinet from French-Italian Virgo project and David Blair of the Australian effort, AIGO. Our today's guest is Prof. Seiji Kawamura of the Japanese endeavor, TAMA.

Seiji Kawamura is an associate professor at National Astronomical Observatory(NAO) at Mitaka, Tokyo, Japan. He was involved in joint Caltech-MIT LIGO project from its early days and worked on the 40m prototype interferometer (at Caltech), suspension system, and advanced R&D for the LIGO project between 1989 and 1997.

In 1997 he joined the TAMA project, the Japanese 300 meter interferometer for the detection of gravitational waves. As the leader of the detector group, he could lead TAMA to attain the world-best sensitivity at that time.

In addition he initiated and has been in charge of the resonant sideband extraction experiment, quantum non-demolition experiment, super-high frequency gravitational wave detection, and displacement-noise-free interferometer. He also leads the Japanese space gravitational wave antenna DECIGO.

Here is Seiji's list of 5 breakthroughs he would like to see in the ongoing worldwide effort to detect gravitational waves using interferometric antennas.
-- 2Physics.com Team]

"- homodyne detection with ponderomotive squeezing to suppress radiation pressure noise

- high-power laser to suppress shot noise

- cryogenic mirror/suspension to suppress thermal noise

- interferometer in space to remove seismic noise and to enhance gravitational wave signals

- displacement-noise-free interferometer to cancel all kinds of displacement noise"

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