Researchers at Paderborn University have developed a new method of measuring distance for systems such as GPS, which achieves more accurate results than ever before. Using quantum physics, the team led by Leibniz Prize winner Professor Christine Silberhorn has successfully overcome the so-called resolution limit, which causes the “noise” we can see in the picture, for example.
Their findings have just been published in the academic journal Physical review X quantum (If PRX) In Physics, the publisher ‘s online journal, the paper is also highlighted with an Expert View – an honor given to only a select few publications.
Physicist Dr. Benjamin Brecht explains the problem of resolution limit: “In laser distance measurements a detector records two light pulses of different intensities with a change in time. The more accurate the time measurement, the more accurately the distance can be determined. Ensuring the time split between pulses is greater than the pulse length, this works well. ”
Problems arise, however, as Brecht explains, if impulses overlap: “Then you can no longer measure the change in time using conventional methods. This is known as the “resolution limit” and is a familiar effect on the photo. Structures or very small structures can no longer be selected. This is the same problem – only with position rather than time. ”
A further challenge, according to Brecht, is to determine the different intensities of two light pulses, simultaneously with their change of time and arrival time. But that’s exactly what researchers have managed to do – “with limited quantum accuracy,” Brecht adds. Working with partners from the Czech Republic and Spain, Paderborn physicists were able to measure these values when impulses overlapped by 90 percent.
Brecht says: “This is far beyond the resolution. Measurement accuracy is 10,000 times better. Using methods from quantum information theory, we can find new forms of measurement that go beyond the limitations of established methods. “
These discoveries could allow significant future improvements in the accuracy of applications such as LIDAR, an optical distance and speed measurement method, and GPS. It will take some time, however, before this is ready for the market, Brecht points out.
Reference: “Reaching the Last Resolution of Quantum Time” by Vahid Ansari, Benjamin Brecht, Jano Gil-Lopez, John M. Donohue, Jaroslav Řeháček, Zdeněk Hradil, Luis L. Sánchez-Soto and Christine Silberhorn, 4 January 2021, If PRX.
DOI: 10.1103 / PRXQuantum.2.010301