Researchers from the University of Edinburgh and the UK's national supercomputing centre EPCC have developed an algorithm that enables ordinary computers to carry out quantum simulations - calculations that imitate the operation of quantum devices. Previously such tasks were within reach only of the world's most powerful supercomputers. This is reported in the journal Science Advances.
According to the authors, running the simulations now requires roughly 5% of the computing power that the supercomputer needed. This makes cheaper and simpler the experiments that are important for understanding the limitations of current quantum computers and for designing more advanced devices.
Quantum computers are in theory capable of calculations beyond even advanced supercomputers, but existing prototypes are small and prone to errors. To build larger and more reliable machines, their operation must be modelled. Until now, however, such simulations required enormous computing resources concentrated in only a few centres around the world.
The new algorithm for the first time allows standard computers to perform so-called Gaussian boson sampling - a simulation designed to demonstrate the advantages of light-based quantum devices (photonic quantum computers). In tests, classical computers using this algorithm were able not only to reproduce but also to surpass the results of some current quantum devices in such simulations.
The researchers are working on scaling the algorithm to carry out even larger simulations with the same computing power. This could allow scientists to model photonic quantum computers with unprecedented detail. Specialists from the Polytechnique Montreal in Canada also took part in the work.
The head of the study, Dr Raul Garcia-Patron Sanchez, noted that their work significantly improved memory use, execution time and energy consumption in simulating photonic quantum devices, making available what previously only a few organisations in the world could afford.