We are excited to invite you to attend a Research Seminar featuring Dr. An Tran, a Senior Scientist at the National Physical Laboratory, United Kingdom.

Lecture Title: Atomic clocks and their applications for time scale generation and high-precision molecular spectroscopy

Speaker: Dr. An Tran, Senior Scientist, Optical Frequency Metrology Group, National Physical Laboratory, UK
Time:  2 PM – 3 PM, February 17, 2025
Location: C402, VinUniversity

In this talk, the speaker first introduces the research activities within the Optical Frequency Metrology group at the National Physical Laboratory (NPL), including the development and operation of state-of-the-art optical atomic clocks, laser frequency stabilization, and optical frequency comparison/dissemination techniques.

Dr. An Tran then demonstrates the application of optical atomic clocks to generate real-time optically steered timescales, towards a redefinition of the SI second. Via an optical frequency comb, optically steered timescale UTCx(NPL) is realized in real-time by calibrating the frequency of hydrogen masers against the NPL’s optical atomic clocks. The performance of the experimental timescale has been analyzed via comparisons against the UK national time scale UTC(NPL) (steered by an NPL-Cesium fountain microwave clocks) and Coordinated Universal Time (UTC, published by BIPM).

Finally, the speaker presents a high-resolution mid-infrared spectrometer traceable to primary frequency standards. It is based on a quantum cascade laser working at 10 mm whose frequency is referenced to a Cesium fountain clock (potential with optical atomic clocks). The spectrometer has been used to determine the rovibrational frequencies of different polyatomic molecules with an absolute uncertainty of the kHz-level and below.

About the Speaker:
An Tran is a Senior Scientist working in the Time and Frequency department. He obtained a PhD degree from Université Sorbonne Paris Nord in 2019. His PhD thesis focussed on the development of ultra-high resolution molecular spectrometers using ultra-stable and SI-traceable quantum cascaded lasers in the mid-infrared domain. He spent two years doing a postdoc at the Department of Chemistry, University of Oxford, developing ultra-sensitive continuous-wave cavity-enhanced polarimetry for optical rotation measurement of chiral molecules.

He joined the Optical Frequency Metrology group at NPL in January 2022. His current research focuses on optically steered time scale generation using the NPL state-of-the-art optical atomic clocks; ultralow-noise microwave synthesis from ultra-stable optical references; laser frequency stabilisation; and development of optical frequency combs for compact optical clocks and other applications.