Chinese scientists achieve high-power quantum computing

If early mechanical computers were never introduced to expand people's computing ability, the invention of the atomic bomb would have gone out the window, and human history would have been rewritten.

This highlights the significance of computer simulation in scientists' exploration of the physical world, which also explains their strong motivation in continuously pursuing higher computing power.

In a recent case, Chinese scientists managed to tremendously enhance such power — they succeeded in performing quantum simulation with atoms in extraordinarily cold conditions.

In physics, quantum refers to the minimum amount of any physical matter. Like the rotation and revolution of the Earth, quantum spins and moves at the same time, and sometimes can be twisting together, which is called spin-orbit coupling — the interplay of a quantum's 'rotation' and 'revolution'.

"The most exciting discovering in physical theories exists in the particles with spin-orbit coupling effect," said Liu Xiongjun, a professor of physics from the Peking University.

According to Liu, spin-orbit coupling is the key to understanding some most significant discoveries in recent years, such as the topological superconductivity and the Quantum Spin Hall effect, in the development of new energy and new materials.

However, it is virtually impossible to conduct precise studies on such quantum effect in realistic experiment, given the extremely complex environment required.

"That is where computers take better place. We can use a computer to simulate the process and observe the physical properties of different particles," Liu said.

Nonetheless, such simulation requires a computation capacity far beyond that of any conventional computers. So scientists from the University of Science and Technology of China and Peking University proposed and built a two-dimensional spin-orbit coupling system to simulate the process directly, without any computation.

They first held atoms in position by cooling them to extraordinarily low temperature, and then used laser beams to make them move in a way that caused spin and movement to be twisted together on a plane.

This achievement was published in the prestigious journal Science on October 7.

"The two-dimensional spin-orbit coupling system gives us a new tool to look into the laws of physical world. I believe that major discoveries could be made from the system within five years," said Pan Jianwei, a top physicist from the University of Science and Technology of China and an author of the latest paper.

"Now the whole world's physicists are racing against each other to develop a quantum computer. Although a general-purpose quantum computer may be the story two or three decades later, now we can already use quantum simulating technology to serve some special purpose, or mimicking some quantum matters that even beyond our present knowledge," Pan said.