Scientists at the University of Paderborn have succeeded in developing a new method of distance measurement for systems such as GPS, the results of which are more precise than ever before. With the help of quantum physics, the team led by Leibniz Prize winner Prof. Dr. Christine Silberhorn overcome the so-called resolution limit, which z. B. ensures the familiar noise in photos. The results have now been published in the journal "Physical Review X Quantum" (PRX Quantum). In “Physics”, the publisher's online magazine, the paper was also recognized with an expert comment - a highlight that is only given to selected publications.
Physicist Dr. Benjamin Brecht explains the problem of the resolution limit: “In laser distance measurements, a detector registers two light pulses of different brightness with a time difference. The more precise the time measurement, the more precise the length determination. As long as the time interval between the pulses is greater than the length of the pulses, everything is fine. ”According to the scientist, it becomes problematic when the pulses overlap:“ Then the time difference can no longer be measured using conventional methods. This is called the resolution limit and you know the effect of photos. Very small structures or textures can no longer be resolved. That is the same problem - only in place instead of in time. "
According to Brecht, another challenge is to determine the different brightnesses, the time difference and the arrival time of two light pulses simultaneously. But that is exactly what the scientists have succeeded in doing - "with quantum-limited accuracy," as Brecht adds. Together with partners from the Czech Republic and Spain, the Paderborn physicists were able to measure these values even when the pulses overlapped 90 percent. Brecht says: “That is far beyond the resolution limit. The accuracy of the measurement is 10,000 times better. Using methods of quantum information theory, new types of measurements can be found that overcome the limitations of established methods. "
The results could significantly improve the accuracy of applications such as LIDAR, a method for optical distance and speed measurement, and GPS in the future. But it will take some time until it is ready for the market, says Brecht.