Eugene Tsao, University of Colorado Boulder, Boulder, USA

Library, A.2.500, Staudtstr. 2

Location details

Abstract:

The measurement and manipulation of coherent optical fields have been transformed by the optical frequency comb, enabling the most precise timekeeping, broad bandwidth precision spectroscopy, and the generation of nearly any coherent field—seamlessly connecting the electromagnetic spectrum from hertz to petahertz. These applications involve the interference of a frequency comb with another coherent light source, such as another frequency comb or a single frequency continuous-wave laser. However, coherent light represents only one type of light. The vast majority of light emanates from “black bodies” such as stars. This thermal light carries profound information about the universe and humanity's place within it. Other types of light defy classical electromagnetism and are known as quantum light, which may play roles in quantum computation and quantum-enhanced metrology. However, the use of frequency combs with thermal and quantum light is largely unexplored, and the fundamental limits to such measurements are undefined. In this talk, I will cover recent work revealing previously unknown fundamental sensitivity limits in optical frequency comb interferometry with coherent, thermal, and quantum light.

To measure broadband thermal light, I will share a new technique called dual-comb correlation spectroscopy and theoretical and experimental work uncovering the fundamental sensitivity limits of dual-comb correlation. I will also share how this work lays groundwork not only for thermal spectroscopy but also in long-baseline synthesis imaging. Comb-based measurements break typical quantum optics assumptions—such as large and mode-matched local oscillators—necessitating new measurement operators. I will share newly derived operators that enable the assessment of quantum advantage in frequency comb metrology. Moreover, this framework reveals that the conventional comb-based shot noise limit is not the standard limit in quantum optics, and I will share efforts to reach this “standard” quantum limit. Lastly, I will share recent work in squeezed dual-comb spectroscopy.