Dr Yu-Hung Lien PhD

Dr Yu-Hung Lien

School of Physics and Astronomy
Application Engineer

Contact details

UK Quantum Technology Hub Sensing and Timing
School of Metallurgy and Materials
University of Birmingham
B15 2TT

Yu-Hung Lien is an application engineer in Quantum Technology Hub for Sensing and Timing.

Yu-Hung’s research interests mainly focus on atomic, molecular and optical (AMO) physics, photonics and their applications in quantum sensing and fundamental physics. Yu-Hung has published more than 20 research papers in scientific journals in the fields of high precision laser spectroscopy, highly stably frequency agile laser systems, optical frequency metrology, atom interferometry, cavity QED, and metasurface.


  • PhD in Physics, National Tsing Hua University, Hsinchu, Taiwan, 2003
  • MSc in Physics, National Tsing Hua University, Hsinchu, Taiwan, 1994
  • BSc in Physics, National Central University, 1992


Yu-Hung started his career from high precision laser spectroscopy on few-body molecular systems.

After finishing his PhD, he expanded his research and employed optical frequency comb and pursued absolute frequency measurement of several atoms and molecules for the interests in both fundamental physics and metrology. Meanwhile, he was keen to use this knowledge to tackle some real-world problems like breath analysis and supervised several highly sensitive spectroscopic studies including multi-pass White cell spectroscopy and tuning-fork photoacoustic spectroscopy for detecting common volatile organic compounds (VOCs) found in breath analysis.

Throughout his years in the group, he developed his expertise on scientific laser systems.

Yu-Hung was a key member of a NTHU (National Tsing-Hua University, Taiwan)—ITRI (Industrial Technology Research Institute, Taiwan) joint research project on the bending performance of flexible LCD displays. His contribution was to design an automatic substrate bending testing platform for the flexible LCD samples.

In 2009, he was awarded a TRIL fellowship of ICTP (Trieste, Italy) and joined Prof. Guglielmo Tino’s group at the University of Florence, Italy. He worked on a project, MAGIA, to determine the Newtonian gravitational constant G to 100 ppm accuracy by a quantum gradiometer. This is a notoriously difficult quantity to measure, and due to conflicting results is one of the least accurately known constants. By using a conceptually different methodology, in particular a gravity gradiometer based on atom interferometry (AI), the group aimed to produce an independent measurement which could address the dispersion in values included in the CODATA (Committee on Data for Science and Technology) evaluation of G. My work predominantly revolved around the characterisation and suppression of noises and biases which subsequently paved the way for the final G measurement which was published in Nature in 2014. In particular, Yu-Hung’s work significantly contributed to reducing the uncertainty from 1700 ppm in 2008 to 150 ppm in 2014.

Yu-Hung then joined the Centre for Cold Matter (CCM) at Imperial College London and worked for Prof. Edward Hinds, studying cavity quantum electrodynamics (Cavity QED or cQED) in the fast cavity regime. Having been inspired by the concept of heterogeneous quantum systems, he also worked with Dr. Jaesuk Hwang and later Dr Alex Clark, who were both members of CCM, on single molecular quantum emitter systems based on dibenzoterrylene (DBT). The team hoped to demonstrate the cooperation between cQED systems based on Rb and DBT. Yu-Hung was also involved in the early design phase of atom interferometric accelerometers which were to be used in experiments to detect the chameleon force and to explore the potential for inertial navigation.

In 2015, Yu-Hung joined the Quantum Technology Hub (QTH) for Sensors and Metrology in the University of Birmingham, under Prof. Kai Bongs, leading the development of the first generation of transportable absolute gravimeters based on AI. One of Yu-Hung’s key successes has been to solve a bias issue caused by parasitic interferometers which are induced when unwanted optical frequencies are present in the laser system.

From 2020, Yu-Hung has been leading the development of a high data rate cold atom quantum gravimeter in QTH navigation work package. The project is to build the quantum gravimeter and explore applications in dynamical environments, e.g. gravity map matching navigation.



Postgraduate supervision

Supervision of research PhDs in quantum technology


Quantum sensing

  • Atom interferometry
  • Quantum gravimetry


  • Highly stable laser systems
  • Optical metasurface components

Cold atom physics

  • Cavity QED
  • Determination of fundamental constants
  • Optical frequency metrology
  • High precision laser spectroscopy