T1 – Tuesday 27/9, 08:30-10:00

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08:30 – 10:00 Tuesday Plenary Session (T1) Plenary Auditorium 10/11/12

08:30 Successful Precision 300-THz Laser Interferometry For Gravitational-wave Detection T1.1
David Shoemaker
Kavli Institute, MIT, United States

The Laser Interferometer Gravitational-wave Observatory (LIGO) is the US endeavor to establish a new astronomy of gravitational waves. The LIGO Laboratory consists of the two institutions, California Institute of Technology and Massachusetts Institute of Technology, and two observatories: one in Hanford, Washington, and the other in Livingston, Louisiana (both in the USA). It is funded by the US National Science Foundation, with contributions for the Advanced LIGO instrument from the UK, Germany, and Australia.
Gravitational waves are a prediction of Einstein’s theory of General Relativity, and can be seen as an inevitable consequence of the fact that changes in the position of massive objects must lead to a change in the gravitational field, and the finite speed of propagation of information (the speed of light). Einstein’s theory predicts that there will be strains in space which propagate at the speed of light, and that the amplitude of the waves will be proportional to the non-spherical acceleration of mass. Unfortunately, space is very ‘stiff’ and to make conceivably measurable gravitational waves requires objects of the order of the mass of our Sun accelerating at speeds approaching the speed of light.
We describe the successful detection of gravitational waves with the LIGO detectors, and give some technical insights into the measurement challenges.

09:15 Metamaterials For THz Quantum Detection T1.2
Carlo Sirtori
Université Paris Diderot, France

In the THz spectral region quantum detectors are intrinsically limited by the small energy of the electronic transition involved in photon absorption. To overcome this problem and improve detector performances, we propose novel approaches in which concepts borrowed from high frequency electronics and metamaterials are exploited to realize THz detectors. In particular, we have investigated sub-wavelength metallic antennas and L-C resonators that enable THz detection using two very different schemes: Patch-antennas coupled to microcavities and optomechanical split-ring resonators. In the first scheme, we have developed plasmonic antennas that collect photons from the free space and also act as microcavities. The antenna permits to gather photons from a much larger area than that of the pixel, while the microcavities effect increases its quantum efficiency. With these devices we were able to increase the temperature of operation above 20K of very sensitive THz detectors.
The second detection scheme is an entirely new approach that combines concepts of circuit electronics and optomecanics. The detector is a high frequency electronic resonator (split ring resonator at 2.5 THz) realized with a flexible arm that acts as a cantilever. Under THz illumination a dynamic distribution of charges with opposite signs appears on both plates of the capacitors (the gap of the split ring resonator). This results into a quasi-static Coulomb force that tend to close the gap of the capacitor and sets the cantilever in motion. The amplitude of this mechanical movement is directly related to the intensity of the incident THz wave, and can be read-out optically with sub-picometer precision. By calibrating very accurately the noise properties of the detection scheme, we were able to precisely determine its noise equivalent power, which is on the order of NEP = 500 pW/Hz1/2. We believe that the use of subwavelength structures and metamaterials will be extremely beneficial for enhancing the performance of quadratic quantum detector in the THz frequency range.