Quantum computers learn how to simulate quarks

Researchers at University of Waterloo’s Institute for Quantum Computing (IQC) have reached a milestone in quantum information science: using a quantum computer to simulate how matter can behave in extreme environments, like the early universe after the big bang. 

The researchers simulated a theory called quantum chromodynamics, that helps describe how quarks interact at defined matter density and temperature, key parameters for modelling large, dense physical systems.  

“The stability of all matter is based on this theory and describes how quarks ‘talk’ to each other,” said Dr. Christine Muschik, IQC faculty and professor in the Department of Physics and Astronomy. “At IQC, we developed a new theoretical and experimental approach as a tool for quantum computation.”  

Muschik collaborated with IQC postdoctoral fellows Drs. Abhijit Chakraborty and Yasar Atas, along with Dr. Randy Lewis at York University and Dr. Norbert Linke at the University of Maryland, where the simulation ran on a trapped ion quantum computer. 

To make this simulation possible, the team introduced two key innovations. The first adds a process after the simulation is complete, without adding computing power, to make sure the results  follow nature’s fundamental symmetry rules. The other method encodes information into the natural motion of ions, which typically isn’t used for quantum information processing. This new approach makes more efficient use of existing quantum resources: by doubling the register size available for computing, it can process more complex algorithms.  

“There is so much about nature that we just don’t know,” Chakraborty said. “We can write a set of equations to describe a system but understanding how the system behaves under different parameters is another story. For large, dense physical systems like in the early universe, we need to control parameters such as temperature and density, and our new method delivers both.”