World first for ultracold quantum simulation

19 September 2019

Physicists from the Hong Kong University of Science and Technology (HKUST) and Peking University (PKU) have successfully created the world's first 3-D simulation of topological matter consisting of ultracold atoms.

Previous attempts at such simulations have been limited to lower dimensions, due to challenges on how to characterise 3-D band topology in atomic systems. This breakthrough paves the way for further investigations of new topological matter that cannot be well realised in solids, and may allow physicists to model unusual phases of matter.

Dr Gyu-Boong Jo (Croucher Innovation Award 2016), Associate Professor from the Department of Physics at HKUST, collaborated with Professor Xiong-Jun Liu from the School of Physics at PKU. They devised an artificial crystal lattice structure, previously proposed by the PKU group, to model ultracold atoms prepared at 30 billionths of a degree above absolute zero.

“Our work opens up many possibilities for developing new topological materials that do not occur naturally,” said Jo. “This development demonstrates there is a new possibility to explore complex topological material in 3-D, and will provide a useful platform for quantum simulation.”

The research was recently published online in Nature Physics.

Three-dimensional band topology is experimentally mapped out showing nodal lines in good agreement with theoretical prediction.

Complex topological matter has become the focus of both industrial and academic research because it is seen as a way to make quantum computing more noise free and robust. Today's physical quantum computers are still noisy, and quantum error correction is a growing field of research.

The goal of fault tolerant quantum computing has driven investment into complex topological matter, classified by the geometric properties of the quantum state in material. The topological nature of the material means that it tends to withstand imperfections within an operating system and also holds the potential for other yet unknown exotic properties.

Jo and Liu’s new synthetic quantum matter is a 3-D spin-orbit coupled nodal-line topological semimetal, and exhibits an emergent magnetic group symmetry. The researchers correlated the atom spin with the direction of atomic motion, which made the overall atom behaviour topological.

With such symmetry the team proved that 3-D band topology can be resolved by imaging 2-D spin patterns on the symmetric planes, and further successfully observed the 3-D topological semimetal in their experiments. The detection techniques used can be applied generally to exploring all 3-D topological states of similar symmetries when those become available.

Dr Gyu-Boong Jo is an Associate Professor in the Department of Physics at the Hong Kong University of Science and Technology, where he leads the Laboratory for Ultracold Quantum Gases. He obtained a Bachelor degree in physics and mathematics from Seoul National University in 2003 and completed his PhD in atomic physics at the Massachusetts Institute of Technology (MIT). He was a Samsung graduate fellow at MIT from 2004-09. In 2010, he became a postdoctoral fellow at UC Berkeley, joining HKUST in 2013. He received an AKPA Outstanding Young Researcher Award (OYRA) in 2013 and an Early Career Award from Hong Kong’s Research Grants Council in 2014. He was awarded his Croucher Innovation Award in 2016.

To view Dr Jo’s Croucher profile, please click here