In addition, the line of the laser was increased. Now LIGO can detect the transmitters of gravitational waves that are 400 million light-years away from us, which increases the range by 50 percent. Instead of discovering an average of one transmitter per month as before, the improvements should now enable him to measure a new source every week. In addition, the researchers hope to be able to extract more information about the sources from which the gravitational waves originate than before from the signals detected in this way. They are created, for example, when black holes or neutron stars collide and merge.
What the "Quantum Vacuum Squeezer" compresses are, roughly speaking, the quantum fluctuations that superimpose and falsify the measurement of the gravitational waves passing through the interferometer. This is because elementary particles, including photons, are constantly formed and lost in a vacuum. These photons disturb the photons of the laser in the detector. Filtering the actual signal out of the background noise of the quantum fluctuations is very difficult. With the "Quantum Vacuum Squeezer", the researchers have developed a method that changes the vacuum in a way that limits the fluctuations.
LIGO consists of two identical detectors, one in Hanford/Washigton and the other in Livingston/Lousiana. Each consists of two 4 km long tunnels arranged at right angles through which laser beams are sent and reflected by mirrors. The laser beams interfere at the intersection of the arms. As long as the lengths of the two arms of a detector are the same, the light is extinguished. If the arms are of different lengths - because a gravitational wave sweeping over them disturbs space-time briefly and shortens one arm by a thousandth of a proton diameter - this can be seen in the interference pattern. Now better than ever.