This year's Nobel Prize in Physics is awarded to John Clarke, Michel H. Devoret and John M. Martinis for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electrical circuit.
Individual particles can penetrate an insulating energy barrier at certain specific energy levels. This is a quantum mechanical phenomenon known as tunnelling, which has been known for a long time.
This year's Nobel Prize winners conducted experiments in the 1980s with an electrical circuit built from two superconductors with an energy barrier in the middle where tunnelling can be controlled, an arrangement known as a Josephson junction.
A superconductor is a material that is cooled to a temperature at which current can be conducted through the material without any electrical resistance. What happens then is that all the electrons in the material act together as if they were a single particle.
Behaves like an atom
By measuring all the properties of the circuit, they were able to explore and ultimately control the quantum mechanical properties with a precision that had not previously been possible.
"The prize winners' electronic circuit behaves like an atom where the energy levels of the electrons are specific, just as quantum mechanics predicts. The researchers were thus able to regulate the quantum mechanical phenomena with electric current. By connecting several such circuits in a system, you have the beginnings of a quantum computer," explains Mats Granath, senior lecturer in physics at the University of Gothenburg.
Quantum mechanical phenomena are essential for today's transistors in computer microchips. This year's Nobel Prize marked the beginning of the future application of quantum mechanics.
"I work with the development of quantum computers at the Wallenberg Centre for Quantum Technology, hosted by Chalmers University of Technology. There, we utilise various quantum mechanical phenomena to create a supercomputer where the energy levels in the circuits represent the ones and zeros of traditional computers," says Mats Granath.
