Optical interferometry in the Quantum Age

Ou Zhe-Yu

The City University of Hong Kong

Abstract: Interferometry has been widely used in sensing application for precision measurement of a variety of physical quantities. However, the hardware structure and the measurement technique have not changed ever since its invention about one hundred years ago, even though quantum states are employed to reduce the intrinsic quantum noise in the interferometers. This has limited the applicable range of the traditional interferometric technique. For example, the interference paths must be balanced to within the coherence time of the light sources. In this presentation, we will introduce some new quantum approaches to interferometry. Among them is the approach by hardware changes. We will review a number of quantum advantages over traditional methods. Another one is the adoption of quantum measurement technique. This can break the limitation of finite coherence time in traditional interferometry and broaden the applicable range of interferometric techniques. The latter approach has potential applications in long-baseline high resolution astronomy and LIDAR technique. In addition to practical applications, when the method is applied to single-photon state as input, this unconventional phenomenon has fundamental implication on the complementarity principle of quantum interference.

Bio: Professor Ou obtained his BS in 1984 from Peking University and his Ph.D. in 1990 from University of Rochester. He is now a chair professor in City University of Hong Kong. Professor Ou is an expert in quantum optics, especially in quantum interference, for which he is famous for the Hong-Ou-Mandel interferometer. His current research focuses on quantum metrology, quantum sensing, quantum state engineering, and the fundamental quantum interference effects. Professor Ou is a fellow of American Physical Society and of Optica (formerly Optical Society of America) and now serves as an Associate Editor of OPTICA Quantum.