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Jac Londe

Squeezed light a small step forward toward detecting gravitational waves - 0 views

arstechnica.com/...ecting-gravitational-waves.ars

light waves onde science pĥoton

shared by Jac Londe on 20 Sep 11 - No Cached
  • Gravitational waves are generated by accelerating masses. So, our planet, which is constantly accelerating towards the sun, is sending out a constant stream of gravitational waves. Just really small ones. Likewise, colliding neutron stars will emit a strong burst of gravitational waves. How strong? Well, if the stars were on the other side of our galaxy, a one meter bar on Earth would elongate by about 0.1am (attometer = 10-18m). 
  • orbit of an electron around a hydrogen atom (about 0.05nm),
  • In a light field, the amplitude (a measure of the brightness of the light) and the phase (which controls how to combine light fields) can't both be measured with absolute accuracy—even if you had the perfect measuring device. You can picture the problem as bunches of photons popping into and out of existence, causing the phase and amplitude of the of the light to jitter around. This doesn't add or subtract energy, but it does continuously redistributes the energy along the light beam.
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  • You might think that a photon here or there shouldn't make a difference, but the scaling isn't independent of the laser light entering the interferometer. If you have one photon, you will have a photon of noise. If you have four photons, you will have two photons of noise. The noise increases slower than the signal and the laser power is increased. So, the easiest way to improve the signal to noise ratio is to crank up the power.
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