Accurate time-delay measurement is one of the most important parts of today's technologies, and overcoming the so-called resolution limit, which causes the noise you see in photos and many other problems, has now been made possible using quantum physics thanks to the researchers at Paderborn University.
The team of scientists has developed a new way of distance measurement for systems such as LIDAR and GPS. Their method enables more precise results than ever before, 10,000 times better, to be exact.
The study was published in the academic journal Physical Review X Quantum (PRX Quantum).
What is the resolution limit?
There are many challenges that arise within the realm of resolution limit; however, the researchers were able to overcome them by using methods from quantum information theory.
Physicist Dr. Benjamin Brecht, who is one of the authors of the "Achieving the Ultimate Quantum Timing Resolution" study, explained the resolution limit problem, saying: "In laser distance measurements a detector registers two light pulses of different intensities with a time difference. The more precise the time measurement is, the more accurately the distance can be determined. Providing the time separation between the pulses is greater than the length of the pulses, this works well."
However, when the said pulses overlap, problems begin to rise since the scientists can't measure the time difference with conventional methods any longer. "This is known as the 'resolution limit' and is a well-known effect in photos. Very small structures or textures can no longer be resolved. That's the same problem—just with position rather than time," Brecht continued.
Methods from quantum information theory
Determining the different intensities of two light pulses at the same time with their time difference and the arrival time poses another challenge that is hard to overcome. Now, researchers have managed to do just that.
The team of scientists was able to measure these values when the pulses overlapped by 90%. According to Brecht, "This is far beyond the resolution limit. The precision of the measurement is 10,000 times better. Using methods from quantum information theory, we can find new forms of measurement which overcome the limitations of established methods."
The researchers wrote, "We experimentally resolve temporal separations 10 times smaller than the pulse duration, as well as imbalanced intensities differing by a factor of 10². This represents an improvement of more than an order of magnitude over the best standard methods based on intensity detection."
This study could improve the precision of applications such as LIDAR and GPS in the future.