Quantum technology sharpens resolution


NUS scientists have discovered new optical techniques that enable the separation between two light sources to be measured more precisely than current approaches. The novel technique to measure the separation of two light sources, no matter how close they are, was first tested by researchers at the Centre for Quantum Technologies (CQT).


These techniques could potentially improve the resolution of microscopes and telescopes. Conventional methods of imaging often experience blurring and noise due to the wave and particle nature of light. This problem particularly hinders the study of fluorescent particles in microscopy and binary stars in astronomy.


"This is our fastest ever paper from concept to result," says CQT's Prof Alexander LING, who set Ph.D. student TANG Zong Sheng and Research Fellow Dr Kadir DURAK working on the project after learning about the proposal from its inventor, his NUS colleague Prof TSANG Man Kei, head of the Quantum Measurement group at NUS’ Department of Electrical and Computer Engineering. Prof Tsang presented his ideas at a CQT seminar in November 2015 titled "Killing Rayleigh's Criterion by Quantum Measurement". A standard concept in optics for over 100 years, Rayleigh's criterion defines the minimum distance between two point light sources that can be resolved. If the points get closer together, you can no longer measure their separation.


With members of his group, Prof Tsang used ideas from quantum metrology. Their calculations revealed that smarter quantum optical methods can extract the full information contained in two typical light sources about their separation, allowing it to be more accurately measured.


At CQT, Zong Sheng built the experiment as part of his Ph.D. training, making him first author on his first paper, just a few months into his Ph.D. He said, " The experiment was surprisingly easy to construct. Our first setup didn't work but we had some ideas for what to change." The experiment uses a modified version of a Mach-Zehnder interferometer, making a proof-of-principle measurement on light emitted from an optical fibre.



CQT PhD student Tang Zong Sheng built an experiment to test a new super-resolution imaging technique – making him first author on his first paper, just a few months into his PhD