【Date and Time】12-Oct-2026 10:00am (Beijing time)

【Venue】Room 526

【Host】 Lai Zhou (BAQIS)

【Language】English

【Title】New developments in quantum and classical optical interferometers

【Speaker】Zhe Yu Jeff Ou, City University of Hong Kong, China

【Abstract】

Interferometry is widely used in sensing applications, yet both its hardware and methods of observation have remained largely unchanged since its invention centuries ago. The introduction of quantum techniques has the potential to revolutionize this long-established technology.

First, a new type of quantum interferometer known as SU(1,1) interferometers can be formed by using nonlinear parametric processes as wave splitting and recombination elements, replacing traditional linear beam splitters in the hardware of interferometers. Due to the nonlinear interaction, the fields inside such an interferometer become intrinsically entangled and quantum mechanically correlated. This quantum-correlated interferometer exhibits unique properties, which we will review in this presentation. These properties make it superior to classical interferometers in many respects. We will present its various configurations and realizations using different types of waves, such as microwaves, atomic waves (involving both internal and external degrees of freedom), and sound waves. We will discuss its applications in quantum metrology, quantum imaging, quantum spectroscopy, and quantum state engineering.

Secondly, quantum measurement techniques such as photon coincidence measurement and homodyne detection can overcome the finite coherence time limitation in classical interferometry with unbalanced optical paths. We will present the underlying physics through various scenarios and data analysis methods, and discuss potential applications in practical optical sensing—including LIDAR and high-resolution astronomical imaging.

【Brief Bio】

Professor Ou obtained his BS in 1984 from Peking University and Ph.D. in 1990 from University of Rochester. He is now a Chair Professor at the City University of Hong Kong. Professor Ou is an expert in quantum optics, especially in quantum interference, for which he is the co-inventor of the well-known Hong-Ou-Mandel interferometer. He pioneered the field of multi-photon interference, which he summarized in the monograph “Quantum Multi-Photon Interference” published by Springer in 2007. Professor Ou’s current research focuses on quantum metrology, quantum sensing, and more fundamental quantum measurement and quantum coherence problems. Professor Ou is an Associate Editor of Optica Quantum and a Fellow of the American Physical Society, the Physical Society of Hong Kong, and Optica (formerly the Optical Society of America).