Slovenian-led team paves way for miniaturisation of microchips

Ljubljana – A group of researchers led by Dragan Mihailović from the Jožef Stefan Institute (IJS) has made a breakthrough in the research of quantum technologies that could lead to miniaturisation of microchips and use of new materials in computers.

Quantum chaos is a phenomenon that appears in electronic devices a few nanometres in size and could be compared to billiards because much like balls on a billiard table electrons collide in a confined space.

Quantum chaos regulates the behaviour of electrons in computer chips and currently prevents scientists from making them any smaller, Mihailović explained.

The IJS team managed to observe quantum billiard in artificial equilateral triangles with sides as small as two nanometres, which corresponds to only 6 atoms.

The behaviour of a single quantum particle in a confined potential is predicted by the Schrödinger equation, but observing multiple electrons, confined to a small area, is much more challenging.

The team led by Mihailović has managed to demonstrate quantum chaos in extremely small circuits for which they had to develop and manufacture a unique device in cooperation with the Jožef Stefan Institute and Nanocentre.

According to team member Jan Ravnik from the Paul Scherrer Institute in Switzerland, extremely small circuits the size of only a few atoms had to be created to observe the path. “We succeed in making them by using ultra short laser pulses to transform a single atomic layer in tantalum disulphide”, a material that is important in computer development, said Ravnik.

According to Ravnik, the trajectories of electrons were studied using a scanning tunnelling microscope at low temperatures and in ultra-high vacuum, which are the conditions in which quantum computers operate.

Jaka Vodeb from the Jožef Stefan Institute explained that calculating the trajectory of an electron in quantum billiard was a challenge for classical computers, but the team succeeded in calculating different trajectories that may be expected in different sized structures observed experimentally.

The research offers a new insight into the understanding of the chaotic behaviour of electrons in atom-sized circuits and could pave the way for further miniaturisation and use of new materials in future quantum and classic computers. It has been published in Nature Communications.